Got My Carb Back From the Rebuilder, BUT........
November 6th, 2014, 02:09 PM
#1
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Join Date: Nov 2007
Location: Charleston, West Virginia
Posts: 1,190
Got My Carb Back From the Rebuilder, BUT........
Finally, sent the Quadrajet off my '67 Cutlass to a professional rebuilder.
Got it back and installed.
Didn't have to touch any adjustments. Idle and mixtures adjustments were set perfectly by the rebuilder.
Starts great, runs great and idles great......until it warms up.
For some reason, when the engine reaches operating temperature it idles faster
(no tach, so I can't say exactly how much faster, but too fast).
Have to think carb isn't the problem.
Had the engine out recently for seals and gaskets.
I'm wondering if I didn't get the intake properly resealed causing a vacuum leak
that only happens when the engine is warm.
Also, getting gasoline fumes like it's running rich.
When I try to "lean" the mixture, it didn't run right so I had to put the adjustments back where they were.
I'm using the original single breaker point ignition system.
I wonder if it's just "tired and not making a hot enough spark for a good, complete burn.
Maybe I need a "hotter" ignition system like an HEI.
Thing is before I had the engine out, I didn't have these problems.
Any thoughts from REAL mechanics?
Got it back and installed.
Didn't have to touch any adjustments. Idle and mixtures adjustments were set perfectly by the rebuilder.
Starts great, runs great and idles great......until it warms up.
For some reason, when the engine reaches operating temperature it idles faster
(no tach, so I can't say exactly how much faster, but too fast).
Have to think carb isn't the problem.
Had the engine out recently for seals and gaskets.
I'm wondering if I didn't get the intake properly resealed causing a vacuum leak
that only happens when the engine is warm.
Also, getting gasoline fumes like it's running rich.
When I try to "lean" the mixture, it didn't run right so I had to put the adjustments back where they were.
I'm using the original single breaker point ignition system.
I wonder if it's just "tired and not making a hot enough spark for a good, complete burn.
Maybe I need a "hotter" ignition system like an HEI.
Thing is before I had the engine out, I didn't have these problems.
Any thoughts from REAL mechanics?
November 6th, 2014, 03:20 PM
#2
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Join Date: Nov 2008
Location: Redmond, Oregon
Posts: 3,334
I have used a propane hand torch with a hose on the nozzle (not lite) to use as a tool to find the leak. the engine will speed up when you put the hose to the right spot. Common is at the ends of the intake.
November 7th, 2014, 06:17 AM
#3
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Join Date: Sep 2011
Location: Plano, TX
Posts: 1,899
If it's running rich, then an air leak will let it run fast.
I'd just bet that the idle cam isn't coming off the fast idle step properly. It's on the right side of the carb, between the choke and the carb. There's a tab that sticks up and out. When it's idling fast, see if pulling that tab towards the front of the engine gets the speed back down.
I'd just bet that the idle cam isn't coming off the fast idle step properly. It's on the right side of the carb, between the choke and the carb. There's a tab that sticks up and out. When it's idling fast, see if pulling that tab towards the front of the engine gets the speed back down.
November 7th, 2014, 06:43 AM
#4
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Location: The Hudson Valley
Posts: 21,183
Which seals and gaskets did you change? It definitely wouldn't hurt to check for intake leaks (or disconnected lines).
Did the carb come with instructions? I've never heard of one that didn't need to be set up after installation.
If not, I would call the professional rebuilder - the carb seems to be the main thing you've changed, so I would start there, after leak checking.
- Eric
Did the carb come with instructions? I've never heard of one that didn't need to be set up after installation.
If not, I would call the professional rebuilder - the carb seems to be the main thing you've changed, so I would start there, after leak checking.
- Eric
November 7th, 2014, 03:06 PM
#5
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The strange thing is it idles fine after cold start.
Fast idle cam and linkage all work properly.
It fast idles, as it should, until the engine warms up.
Problem is, instead of idle slowing to normal, it speeds up even faster
AFTER the engine reaches operating temperature.
I changed intake gaskets during re-gasketing.
I've checked intake for leaks with spray break cleaner.
I've used this method before and it worked very well. No indication of leaks.
I'm afraid it may be leaking on the bottom side in the lifter valley where I can't check it.
Yes, I was pleasantly surprised that the adjustments on the carb were perfectly set.
I messed with the adjustments to see if I could fix my problem.
Didn't help so I set them back where they were.
I may be wrong, but, I don't think the carb is the problem.
Just can't figure out what IS the problem
It looks like these guys did a great job.
Custom Rebuilt Carburetors, Middlesex, N.J.
Fast idle cam and linkage all work properly.
It fast idles, as it should, until the engine warms up.
Problem is, instead of idle slowing to normal, it speeds up even faster
AFTER the engine reaches operating temperature.
I changed intake gaskets during re-gasketing.
I've checked intake for leaks with spray break cleaner.
I've used this method before and it worked very well. No indication of leaks.
I'm afraid it may be leaking on the bottom side in the lifter valley where I can't check it.
Yes, I was pleasantly surprised that the adjustments on the carb were perfectly set.
I messed with the adjustments to see if I could fix my problem.
Didn't help so I set them back where they were.
I may be wrong, but, I don't think the carb is the problem.
Just can't figure out what IS the problem
It looks like these guys did a great job.
Custom Rebuilt Carburetors, Middlesex, N.J.
November 8th, 2014, 04:10 AM
#7
'87 Delta 88 Royale
Join Date: Dec 2010
Location: Margate, England
Posts: 2,514
Check the timing isn't over advanced, if it's correctly timed I think you can rule out ignition problems. If it wasn't making a spark it would have misfiring issues, certainly not making it run faster.
You don't need a mega powerful ignition system for a stock engine, a spark hot enough to ignite the mixture is all it needs, a bigger spark won't make it ignite any better.
Roger.
You don't need a mega powerful ignition system for a stock engine, a spark hot enough to ignite the mixture is all it needs, a bigger spark won't make it ignite any better.
Roger.
November 8th, 2014, 09:30 AM
#8
CH3NO2 LEARN IT BURN IT
Join Date: Jul 2010
Location: Land of Taxes
Posts: 5,011
divorced choke or electric conversion? Is the choke pulling off properly? When its fast idling which step is the curb idle screw on. Is that position different from when it was on the choke warming up. In other words when you kick the choke off what happens to the linkage? Once warmed up try backing the curb idle setting out. Does the idle follow?
November 8th, 2014, 04:24 PM
#9
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Location: Charleston, West Virginia
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Is it a Jetstar? Big Block?
My car is an automatic, 700R4, so the fast idle when warm is a hassle.
I have to put it in neutral at stop lights, shut it off before I put it in "Park"
so it doesn't "diesel".
November 8th, 2014, 04:32 PM
#10
November 8th, 2014, 06:29 PM
#11
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I though the 375HP was only available in the Starfires and 98's, 385 in the Toros.
Didn't know 375 was an option in the 88's. Checked my '66 & '67 Dealer Brochures.
I see you're right.
I thought only the 365HP came in the 88's.
I have what I think is a '66 365HP, 425 that's been sitting on a cart in my shop for 15 or 20 years.
Came out of a "66 Jetstar 88.
Thought I'd eventually use it in something, but, that's looking more doubtful as time passes.
Considering letting it go.
Tried lowering the idle while it was idling fast.
As soon as I lowered it just slightly, it started running rough and stalled,
so I put it back where it was.
Did the same thing when I turned it down after starting cold.
The point where it idles won't go any lower, hot or cold.
November 8th, 2014, 06:53 PM
#12
Ed what you describe seems like a carb problem or gasket/vacuum leak. Maybe there is a problem with that carb....maybe send it back and have them go over it or test run it.
The Sfire 425 was available in the 98 and Delta only except for the Police Optioned Dynamic 88. Only small blocks in the 65 and 66 Jetstar. The 65 Jetstar I was 425 powered.
The Sfire 425 was available in the 98 and Delta only except for the Police Optioned Dynamic 88. Only small blocks in the 65 and 66 Jetstar. The 65 Jetstar I was 425 powered.
November 8th, 2014, 07:00 PM
#13
I had an issue like this . It was with a holley 650 I had to lean the idle out since too much of the transition ports where exposed making it pig rich and once I did it . it worked very well I did two things to remedy this I bought pre drilled throttle plates it worked but I was closel to the other end of the spectrum then I realized I could open the secondary throttle plates and I got the idle dialed in . Although its not apples for apple since its a holley vs qjet the metering circuits are very important . It came down to the idle metering. I have had carburetors idle fine with relatively big vacuum leaks like an open bolt hole on the mouting pad that goes all the way down into the intake plenum big. Currently I have a holley that has a surge during idle while hot but I have not tuned it at all. It came off a buddies car which he tuned to work with his 355 sbc.
November 9th, 2014, 02:49 PM
#14
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Right now the problem is I hate to send it back before I confirm that my intake gasket isn't leaking.
I'm a couple of months into the 6 month warranty and I just don't have time to pull the intake right now.
I've checked the top side for leaks and didn't find any.
I don't know of a way to check the bottom unless there's a way to detect vacuum from the valve cover.
Even if there is, a minor leak would probably be hard to detect.
I plan to call the carb people tomorrow to discuss it.
November 9th, 2014, 03:19 PM
#15
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Join Date: Sep 2013
Posts: 77
Try this when the engine is warm at idle try cupping you hand over the carb dose the rpm increases. If it dose it is lean .if you pull the small vacume line that is not to the distributor and the rpm increases it is rich.
Was the throttle shafts rebushed if there sloppy they can add by pass air at idle.the angle of the spring tension changes when comeing off high idle makeing a bigger air leak.hunting idle rpm are a sign of sloppy throttle shafts.
Was the throttle shafts rebushed if there sloppy they can add by pass air at idle.the angle of the spring tension changes when comeing off high idle makeing a bigger air leak.hunting idle rpm are a sign of sloppy throttle shafts.
November 11th, 2014, 07:05 PM
#16
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Location: Charleston, West Virginia
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For those of you who have been watching this thread, I have an interesting update.
I contacted the carb people and explained my problem.
He immediately asked if I had used the stainless steel shim between the carb base and the intake gasket.
I said that I didn't, but, I remembered the guy I spoke with when the carb was finished told me
they'd send the shim with the carb.
I told him there was no shim sent. He said he'd get one out to me tomorrow.
He explained that it was important to use this shim to insulate the carb from the heat of the crossover.
He explained that the excess heat somehow caused the vacuum to stay high, holding the metering rods
of the power valve open, thus causing the fast idle and the running rich.
I didn't completely understand his explanation, but like I've said before, I'm no carb expert.
I'd never have guessed this shim could cause the problem.
Hopefully, this will take care of it.
I'll revisit Doug Roe's book and try to figure it out.
I contacted the carb people and explained my problem.
He immediately asked if I had used the stainless steel shim between the carb base and the intake gasket.
I said that I didn't, but, I remembered the guy I spoke with when the carb was finished told me
they'd send the shim with the carb.
I told him there was no shim sent. He said he'd get one out to me tomorrow.
He explained that it was important to use this shim to insulate the carb from the heat of the crossover.
He explained that the excess heat somehow caused the vacuum to stay high, holding the metering rods
of the power valve open, thus causing the fast idle and the running rich.
I didn't completely understand his explanation, but like I've said before, I'm no carb expert.
I'd never have guessed this shim could cause the problem.
Hopefully, this will take care of it.
I'll revisit Doug Roe's book and try to figure it out.
Last edited by 67442nut; November 11th, 2014 at 07:07 PM.
November 11th, 2014, 07:08 PM
#17
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November 11th, 2014, 08:48 PM
#19
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The guy seemed pretty confident this was the problem.
I also use the thick gasket like you mentioned.
I'm forced to be optimistic that the carb guy knows what he's talking about,
but, like Eric, I've never heard of such a thing.
If this happens to work, it might be worth a try on your "88".
I'll definitely, post the results of adding the shim.
November 12th, 2014, 02:02 AM
#21
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Join Date: Oct 2013
Location: Matamata, Waikato, New Zealand
Posts: 182
Finally, sent the Quadrajet off my '67 Cutlass to a professional rebuilder.
Got it back and installed.
Didn't have to touch any adjustments. Idle and mixtures adjustments were set perfectly by the rebuilder.
Starts great, runs great and idles great......until it warms up.
For some reason, when the engine reaches operating temperature it idles faster
(no tach, so I can't say exactly how much faster, but too fast).
Have to think carb isn't the problem.
Had the engine out recently for seals and gaskets.
I'm wondering if I didn't get the intake properly resealed causing a vacuum leak
that only happens when the engine is warm.
Also, getting gasoline fumes like it's running rich.
When I try to "lean" the mixture, it didn't run right so I had to put the adjustments back where they were.
I'm using the original single breaker point ignition system.
I wonder if it's just "tired and not making a hot enough spark for a good, complete burn.
Maybe I need a "hotter" ignition system like an HEI.
Thing is before I had the engine out, I didn't have these problems.
Any thoughts from REAL mechanics?
Got it back and installed.
Didn't have to touch any adjustments. Idle and mixtures adjustments were set perfectly by the rebuilder.
Starts great, runs great and idles great......until it warms up.
For some reason, when the engine reaches operating temperature it idles faster
(no tach, so I can't say exactly how much faster, but too fast).
Have to think carb isn't the problem.
Had the engine out recently for seals and gaskets.
I'm wondering if I didn't get the intake properly resealed causing a vacuum leak
that only happens when the engine is warm.
Also, getting gasoline fumes like it's running rich.
When I try to "lean" the mixture, it didn't run right so I had to put the adjustments back where they were.
I'm using the original single breaker point ignition system.
I wonder if it's just "tired and not making a hot enough spark for a good, complete burn.
Maybe I need a "hotter" ignition system like an HEI.
Thing is before I had the engine out, I didn't have these problems.
Any thoughts from REAL mechanics?
November 12th, 2014, 03:34 AM
#22
Oldsdruid
Join Date: Dec 2007
Location: Southside Vajenya
Posts: 10,535
Does this car have a thermal vacuum switch for the distributor vacuum advance?
If so I'm thinking it may be failing. If it's incorrectly sensing overheating it could be switching distributor vacuum over to manifold vacuum and advancing the base timing, which would cause increased idle speed after warmup.
If so I'm thinking it may be failing. If it's incorrectly sensing overheating it could be switching distributor vacuum over to manifold vacuum and advancing the base timing, which would cause increased idle speed after warmup.
November 12th, 2014, 08:01 AM
#23
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Location: Thousand Oaks, CA
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Hi Ed,
I just went through a rebuilt carb situation too. My 68 400 442 was completely rebuilt and "heated up" a bit. The carb was sent out with the specs of the car. It ran ok but needed to be fine tuned. I drove myself nuts trying to fix it myself. I finally talked to the builder and he told me to bring it to him. It was an hour drive (in LA) to his shop. I took the day off and brought it to him. It was the best thing I could have done. The car runs beautiful! I paid him $100 to fine tune everything. He adjusted and changed a few things under warranty. Anyways my 2 cents is don't mess with it, bring it to him (if you can) and have it set up! You should be driving that beauty!
Craig
I just went through a rebuilt carb situation too. My 68 400 442 was completely rebuilt and "heated up" a bit. The carb was sent out with the specs of the car. It ran ok but needed to be fine tuned. I drove myself nuts trying to fix it myself. I finally talked to the builder and he told me to bring it to him. It was an hour drive (in LA) to his shop. I took the day off and brought it to him. It was the best thing I could have done. The car runs beautiful! I paid him $100 to fine tune everything. He adjusted and changed a few things under warranty. Anyways my 2 cents is don't mess with it, bring it to him (if you can) and have it set up! You should be driving that beauty!
Craig
November 12th, 2014, 09:22 AM
#24
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Join Date: May 2006
Location: Bartlesville, Oklahoma
Posts: 1,142
Do you or a buddy have another comparable carburetor you could try, maybe one off a known good running engine? If you put the other carb on and have the same issue, then you know it is not your new carb. If it fixes the problem then you know your new carb is the problem.
November 12th, 2014, 06:32 PM
#25
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Join Date: Nov 2007
Location: Charleston, West Virginia
Posts: 1,190
Not an expert by any means but my 2 cents worth..... As the engine warms up and the inlet manifold also heats up the car will naturally run leaner so if the car starts idling faster (i.e better) it points to the idle mixture being too rich.Idle mixture best checked/changed with a tach and a vacuum gauge, both are cheap and good additions to your car.
Does this car have a thermal vacuum switch for the distributor vacuum advance?
If so I'm thinking it may be failing. If it's incorrectly sensing overheating it could be switching distributor vacuum over to manifold vacuum and advancing the base timing, which would cause increased idle speed after warmup.
If so I'm thinking it may be failing. If it's incorrectly sensing overheating it could be switching distributor vacuum over to manifold vacuum and advancing the base timing, which would cause increased idle speed after warmup.
Hi Ed,
I just went through a rebuilt carb situation too. My 68 400 442 was completely rebuilt and "heated up" a bit. The carb was sent out with the specs of the car. It ran ok but needed to be fine tuned. I drove myself nuts trying to fix it myself. I finally talked to the builder and he told me to bring it to him. It was an hour drive (in LA) to his shop. I took the day off and brought it to him. It was the best thing I could have done. The car runs beautiful! I paid him $100 to fine tune everything. He adjusted and changed a few things under warranty. Anyways my 2 cents is don't mess with it, bring it to him (if you can) and have it set up! You should be driving that beauty!
Craig
I just went through a rebuilt carb situation too. My 68 400 442 was completely rebuilt and "heated up" a bit. The carb was sent out with the specs of the car. It ran ok but needed to be fine tuned. I drove myself nuts trying to fix it myself. I finally talked to the builder and he told me to bring it to him. It was an hour drive (in LA) to his shop. I took the day off and brought it to him. It was the best thing I could have done. The car runs beautiful! I paid him $100 to fine tune everything. He adjusted and changed a few things under warranty. Anyways my 2 cents is don't mess with it, bring it to him (if you can) and have it set up! You should be driving that beauty!
Craig
November 13th, 2014, 06:25 AM
#27
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Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
Perhaps I was too oblique in my post #17.
Stainless steel is a metal.
Metals are good conductors of heat.
A stainless steel shim will conduct heat to the carburetor very well. It will not insulate it.
A stainless steel shim on top of the fiber base gasket (which will insulate from heat) will have no effect whatsoever on heat transfer one way or another.
Please, just swap this with a different carb, find out that it runs fine, and send it back to have it re-rebuilt.
I'm getting old following this thread.
- Eric
Stainless steel is a metal.
Metals are good conductors of heat.
A stainless steel shim will conduct heat to the carburetor very well. It will not insulate it.
A stainless steel shim on top of the fiber base gasket (which will insulate from heat) will have no effect whatsoever on heat transfer one way or another.
Please, just swap this with a different carb, find out that it runs fine, and send it back to have it re-rebuilt.
I'm getting old following this thread.
- Eric
November 13th, 2014, 08:12 AM
#28
Oldsdruid
Join Date: Dec 2007
Location: Southside Vajenya
Posts: 10,535
He explained that the excess heat somehow caused the vacuum to stay high, holding the metering rods of the power valve open, thus causing the fast idle and the running rich.
Chevrolet used those metal shims on a lot of their high performance big-blocks to deflect radiant heat off the fuel bowl, especially on Holley-equipped engines. Idea was to keep fuel from boiling. Not sure how well it worked. But pretty sure there was a fiber gasket between intake and shim.
November 13th, 2014, 08:18 AM
#29
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I was always taught that the power valve opens under low vacuum conditions. High cruise and idle vacuum holds it down, and low vacuum as in throttle tip-in allowed its spring to push it open and raise the metering rod taper out of the jet. Maybe I'm thinking backwards.
- Eric
November 13th, 2014, 10:46 AM
#31
CH3NO2 LEARN IT BURN IT
Join Date: Jul 2010
Location: Land of Taxes
Posts: 5,011
Please answer the previously asked Qs.........
1. Divorced choke or electric choke conversion? If electric the bi-metal spring could be in wrong.
2. Is the choke pulling off properly during warm up? Or is it working backwards or not at all? Does the little choke pull off canister on the passenger front side of the carb hold vacuum?
3. When its fast idling after warm up and you attempt to "kick" it down, which step is the curb idle screw on? It should be on the smallest step. In other words when you "kick" the choke off what happens to the linkage?
4. Once warmed up try backing the curb idle setting out. Does the idle follow?
5. If we can verify the throttle plates are 100% closed and your still running at high(er) idle that points to a vac leak. So does the fact your Air/Fuel adjustments are unresponsive.
Please follow our suggestions here. Then we can assist digging deeper once the basics are out of the way.
1. Answer my first 5 questions.
2. Verify ZERO vacuum leaks.
3. If you have only metal to metal under the carb, put a standard carb to intake gasket there. Start and run the car to try to duplicate the problem.
4. Buy a vac gauge and plug it into an intake port with car warm & running (dont plug gauge into the carb), relay the vac reading at idle to us. Try to (gently) force the linkage to obtain curb idle settings 550-700rpms warm.
5. install a known good carb if possible.
6. Pull a few spark plugs and relay what they look like visually. Black, brown or white?
7. Verify all ignition timing settings are in spec...initial base timing on the vib damper mark ~10*BTDC with vac advance canister disconnected and plugged off to prevent a vac leak and engine warm. Then plug in the vacuum advance canister at idle. This should produce another 7-10* of timing...now your at 20 ish at curb idle. Verify the centrifugal advance weights & springs under the rotor are present and not sticking.
If heat wick/soak was a problem it will run fine when cold and not when hot. By that I mean smooth idle cold (after choke pull off), rough hot...not high idle condition hot.
Heat soak will cause hard starts when hot. The reason is todays crap gas has a lower boiling point compared to gas from 1967. Thats why it ran well when new. The gas boils out of the bowl and causes hard starting due to the lack of gas in the bowl. The float setting should be set slightly lower the 1967 spec to compensate and prevent splash over. Riser block offs and carb insulators are the fix here. Boil over can be viewed down the carb. When you shut the car off you should see gas burbling out of the shot tubes. You can see splash over when at curb idle looking down carb. Splash over will cause rough idle when hot. The phenolic insulators work well to isolate the heat so does the stacked gasket/stainless insulator.
A Stainless gasket (shim) alone will do noting to isolate heat nor will it prevent vacuum leaks. If all you have on the car now is a stainless gasket between the carb and the intake then Ill guarantee you have a vacuum leak unless the stainless has a gasket on BOTH sides.
Proper carb gasketing example:... in this order....Carb base, gasket material, stainless, gasket material then intake. This set up in this order wont leak but wont do much for heat dissipation unless you have several stacks of the above with a gasket on the intake and carb sides like the old laminated style Mr Gasket insulator. I have that on mine. Been there for many years. Its about 1.5" thick with alternating SS and gasket material. The top and bottom being a gasket. Google it if how Im explaining this makes zero sense.
1. Divorced choke or electric choke conversion? If electric the bi-metal spring could be in wrong.
2. Is the choke pulling off properly during warm up? Or is it working backwards or not at all? Does the little choke pull off canister on the passenger front side of the carb hold vacuum?
3. When its fast idling after warm up and you attempt to "kick" it down, which step is the curb idle screw on? It should be on the smallest step. In other words when you "kick" the choke off what happens to the linkage?
4. Once warmed up try backing the curb idle setting out. Does the idle follow?
5. If we can verify the throttle plates are 100% closed and your still running at high(er) idle that points to a vac leak. So does the fact your Air/Fuel adjustments are unresponsive.
Please follow our suggestions here. Then we can assist digging deeper once the basics are out of the way.
1. Answer my first 5 questions.
2. Verify ZERO vacuum leaks.
3. If you have only metal to metal under the carb, put a standard carb to intake gasket there. Start and run the car to try to duplicate the problem.
4. Buy a vac gauge and plug it into an intake port with car warm & running (dont plug gauge into the carb), relay the vac reading at idle to us. Try to (gently) force the linkage to obtain curb idle settings 550-700rpms warm.
5. install a known good carb if possible.
6. Pull a few spark plugs and relay what they look like visually. Black, brown or white?
7. Verify all ignition timing settings are in spec...initial base timing on the vib damper mark ~10*BTDC with vac advance canister disconnected and plugged off to prevent a vac leak and engine warm. Then plug in the vacuum advance canister at idle. This should produce another 7-10* of timing...now your at 20 ish at curb idle. Verify the centrifugal advance weights & springs under the rotor are present and not sticking.
If heat wick/soak was a problem it will run fine when cold and not when hot. By that I mean smooth idle cold (after choke pull off), rough hot...not high idle condition hot.
Heat soak will cause hard starts when hot. The reason is todays crap gas has a lower boiling point compared to gas from 1967. Thats why it ran well when new. The gas boils out of the bowl and causes hard starting due to the lack of gas in the bowl. The float setting should be set slightly lower the 1967 spec to compensate and prevent splash over. Riser block offs and carb insulators are the fix here. Boil over can be viewed down the carb. When you shut the car off you should see gas burbling out of the shot tubes. You can see splash over when at curb idle looking down carb. Splash over will cause rough idle when hot. The phenolic insulators work well to isolate the heat so does the stacked gasket/stainless insulator.
A Stainless gasket (shim) alone will do noting to isolate heat nor will it prevent vacuum leaks. If all you have on the car now is a stainless gasket between the carb and the intake then Ill guarantee you have a vacuum leak unless the stainless has a gasket on BOTH sides.
Proper carb gasketing example:... in this order....Carb base, gasket material, stainless, gasket material then intake. This set up in this order wont leak but wont do much for heat dissipation unless you have several stacks of the above with a gasket on the intake and carb sides like the old laminated style Mr Gasket insulator. I have that on mine. Been there for many years. Its about 1.5" thick with alternating SS and gasket material. The top and bottom being a gasket. Google it if how Im explaining this makes zero sense.
November 14th, 2014, 04:48 PM
#32
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Thread Starter
Join Date: Nov 2007
Location: Charleston, West Virginia
Posts: 1,190
Perhaps I was too oblique in my post #17.
Stainless steel is a metal.
Metals are good conductors of heat.
A stainless steel shim will conduct heat to the carburetor very well. It will not insulate it.
A stainless steel shim on top of the fiber base gasket (which will insulate from heat) will have no effect whatsoever on heat transfer one way or another.
Please, just swap this with a different carb, find out that it runs fine, and send it back to have it re-rebuilt.
I'm getting old following this thread.
- Eric
Stainless steel is a metal.
Metals are good conductors of heat.
A stainless steel shim will conduct heat to the carburetor very well. It will not insulate it.
A stainless steel shim on top of the fiber base gasket (which will insulate from heat) will have no effect whatsoever on heat transfer one way or another.
Please, just swap this with a different carb, find out that it runs fine, and send it back to have it re-rebuilt.
I'm getting old following this thread.
- Eric
At this point I'm forced to wait until the shim arrives to install it.
Once that's done, I can either rule out the shim being the problem or confirm that it cures it.
I have 4 different '67 carbs. I tried each of them multiple times.
Each had a different problem I couldn't correct.
I rebuilt 2 of them with new kits. Still couldn't make a usable carb.
That's when I gave up and sent one to have it professionally redone.
If I had a good, usable one, I would not have spent $300.00 to have one professionally redone.
This is the second thread I've posted in recent weeks that has become prolonged and tedious.
In both cases, it was not my intention to have this happen.
I wasn't trying to set a new record for most replies to a post.
I was simply trying to get some opinions and/or advice on the subjects.
November 14th, 2014, 07:48 PM
#33
Connoisseur d'Junque
Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
Also, from what I can tell, your problem is not related to the kind of heat that such a shield would protect against.
I would humbly suggest, in that case, that there is something wrong with each of those carburetors, and that that something is something that can be found and fixed, in at least one of them anyway, and that if you have the time and the patience, you might be able to do so without the help of so-called experts.
Ultimately, I would recommend buying or borrowing a cheap carb that is "wrong" for your car (something from a late-'70's pickup, for instance), but that works, and bolting it on, just to confirm whether your problem is related to the carburetor or not.
This is the second thread I've posted in recent weeks that has become prolonged and tedious.
In both cases, it was not my intention to have this happen.
I wasn't trying to set a new record for most replies to a post.
I was simply trying to get some opinions and/or advice on the subjects.
In both cases, it was not my intention to have this happen.
I wasn't trying to set a new record for most replies to a post.
I was simply trying to get some opinions and/or advice on the subjects.
Personally, considering the difference in difficulty between removing the intake manifold and removing the carburetor, I would strongly lobby for finding and installing a substitute carb. before embarking on a potentially fruitless hunt for an elusive vacuum leak.
- Eric
November 14th, 2014, 09:35 PM
#34
Registered User
Thread Starter
Join Date: Nov 2007
Location: Charleston, West Virginia
Posts: 1,190
Please answer the previously asked Qs.........
1. Divorced choke or electric choke conversion? If electric the bi-metal spring could be in wrong.
Stock divorced choke, no conversion.
2. Is the choke pulling off properly during warm up? Or is it working backwards or not at all? Does the little choke pull off canister on the passenger front side of the carb hold vacuum?
Choke is functioning correctly. Since choke pull-off diaphragm is brand new and functioning as it should, I had no reason to check it.
3. When its fast idling after warm up and you attempt to "kick" it down, which step is the curb idle screw on? It should be on the smallest step. In other words when you "kick" the choke off what happens to the linkage?
Since it kicks down to normal idle, as it should, I had no reason to check it.
4. Once warmed up try backing the curb idle setting out. Does the idle follow?
No.
5. If we can verify the throttle plates are 100% closed and your still running at high(er) idle that points to a vac leak. So does the fact your Air/Fuel adjustments are unresponsive.
Idle plates appear to be closing properly.
Please follow our suggestions here. Then we can assist digging deeper once the basics are out of the way.
1. Answer my first 5 questions.
2. Verify ZERO vacuum leaks.
I've checked all vacuum leak possibilities except bottom side of intake.
3. If you have only metal to metal under the carb, put a standard carb to intake gasket there.
Standard gasket is already installed.
Start and run the car to try to duplicate the problem.
4. Buy a vac gauge and plug it into an intake port with car warm & running (dont plug gauge into the carb), relay the vac reading at idle to us.
I have a vacuum gauge. Won't have time to work on the car for several days.
Try to (gently) force the linkage to obtain curb idle settings 550-700rpms warm.
I've tried this. Won't idle at a lower RPM.
5. install a known good carb if possible.
6. Pull a few spark plugs and relay what they look like visually. Black, brown or white?
Haven't pulled plugs since new carb was installed.
7. Verify all ignition timing settings are in spec...initial base timing on the vib damper mark ~10*BTDC with vac advance canister disconnected and plugged off to prevent a vac leak and engine warm. Then plug in the vacuum advance canister at idle. This should produce another 7-10* of timing...now your at 20 ish at curb idle. Verify the centrifugal advance weights & springs under the rotor are present and not sticking.
All this has been done previously and checked out OK.
If heat wick/soak was a problem it will run fine when cold and not when hot. By that I mean smooth idle cold (after choke pull off), rough hot...not high idle condition hot.
Runs fine after reaching operating temp., just idles fast and runs rich.
Heat soak will cause hard starts when hot.
Starts fine when hot.
The reason is todays crap gas has a lower boiling point compared to gas from 1967. Thats why it ran well when new. The gas boils out of the bowl and causes hard starting due to the lack of gas in the bowl. The float setting should be set slightly lower the 1967 spec to compensate and prevent splash over. Riser block offs and carb insulators are the fix here. Boil over can be viewed down the carb. When you shut the car off you should see gas burbling out of the shot tubes. You can see splash over when at curb idle looking down carb. Splash over will cause rough idle when hot.
Doesn't idle rough when hot, just idles fast.
The phenolic insulators work well to isolate the heat so does the stacked gasket/stainless insulator.
A Stainless gasket (shim) alone will do noting to isolate heat nor will it prevent vacuum leaks. If all you have on the car now is a stainless gasket between the carb and the intake then Ill guarantee you have a vacuum leak unless the stainless has a gasket on BOTH sides.
There is no stainless shim on the car. Only the thick, approx. 1/8" paper gasket. As I stated previously, I'm waiting for the carb builder to send the stainless shim.
Proper carb gasketing example:... in this order....Carb base, gasket material, stainless, gasket material then intake. This set up in this order wont leak but wont do much for heat dissipation unless you have several stacks of the above with a gasket on the intake and carb sides like the old laminated style Mr Gasket insulator. I have that on mine. Been there for many years. Its about 1.5" thick with alternating SS and gasket material. The top and bottom being a gasket. Google it if how Im explaining this makes zero sense.
Your explanation is clear.
1. Divorced choke or electric choke conversion? If electric the bi-metal spring could be in wrong.
Stock divorced choke, no conversion.
2. Is the choke pulling off properly during warm up? Or is it working backwards or not at all? Does the little choke pull off canister on the passenger front side of the carb hold vacuum?
Choke is functioning correctly. Since choke pull-off diaphragm is brand new and functioning as it should, I had no reason to check it.
3. When its fast idling after warm up and you attempt to "kick" it down, which step is the curb idle screw on? It should be on the smallest step. In other words when you "kick" the choke off what happens to the linkage?
Since it kicks down to normal idle, as it should, I had no reason to check it.
4. Once warmed up try backing the curb idle setting out. Does the idle follow?
No.
5. If we can verify the throttle plates are 100% closed and your still running at high(er) idle that points to a vac leak. So does the fact your Air/Fuel adjustments are unresponsive.
Idle plates appear to be closing properly.
Please follow our suggestions here. Then we can assist digging deeper once the basics are out of the way.
1. Answer my first 5 questions.
2. Verify ZERO vacuum leaks.
I've checked all vacuum leak possibilities except bottom side of intake.
3. If you have only metal to metal under the carb, put a standard carb to intake gasket there.
Standard gasket is already installed.
Start and run the car to try to duplicate the problem.
4. Buy a vac gauge and plug it into an intake port with car warm & running (dont plug gauge into the carb), relay the vac reading at idle to us.
I have a vacuum gauge. Won't have time to work on the car for several days.
Try to (gently) force the linkage to obtain curb idle settings 550-700rpms warm.
I've tried this. Won't idle at a lower RPM.
5. install a known good carb if possible.
6. Pull a few spark plugs and relay what they look like visually. Black, brown or white?
Haven't pulled plugs since new carb was installed.
7. Verify all ignition timing settings are in spec...initial base timing on the vib damper mark ~10*BTDC with vac advance canister disconnected and plugged off to prevent a vac leak and engine warm. Then plug in the vacuum advance canister at idle. This should produce another 7-10* of timing...now your at 20 ish at curb idle. Verify the centrifugal advance weights & springs under the rotor are present and not sticking.
All this has been done previously and checked out OK.
If heat wick/soak was a problem it will run fine when cold and not when hot. By that I mean smooth idle cold (after choke pull off), rough hot...not high idle condition hot.
Runs fine after reaching operating temp., just idles fast and runs rich.
Heat soak will cause hard starts when hot.
Starts fine when hot.
The reason is todays crap gas has a lower boiling point compared to gas from 1967. Thats why it ran well when new. The gas boils out of the bowl and causes hard starting due to the lack of gas in the bowl. The float setting should be set slightly lower the 1967 spec to compensate and prevent splash over. Riser block offs and carb insulators are the fix here. Boil over can be viewed down the carb. When you shut the car off you should see gas burbling out of the shot tubes. You can see splash over when at curb idle looking down carb. Splash over will cause rough idle when hot.
Doesn't idle rough when hot, just idles fast.
The phenolic insulators work well to isolate the heat so does the stacked gasket/stainless insulator.
A Stainless gasket (shim) alone will do noting to isolate heat nor will it prevent vacuum leaks. If all you have on the car now is a stainless gasket between the carb and the intake then Ill guarantee you have a vacuum leak unless the stainless has a gasket on BOTH sides.
There is no stainless shim on the car. Only the thick, approx. 1/8" paper gasket. As I stated previously, I'm waiting for the carb builder to send the stainless shim.
Proper carb gasketing example:... in this order....Carb base, gasket material, stainless, gasket material then intake. This set up in this order wont leak but wont do much for heat dissipation unless you have several stacks of the above with a gasket on the intake and carb sides like the old laminated style Mr Gasket insulator. I have that on mine. Been there for many years. Its about 1.5" thick with alternating SS and gasket material. The top and bottom being a gasket. Google it if how Im explaining this makes zero sense.
Your explanation is clear.
November 14th, 2014, 09:51 PM
#35
Registered User
Thread Starter
Join Date: Nov 2007
Location: Charleston, West Virginia
Posts: 1,190
All your suggestions and comments are appreciated and well taken.
As I've admitted before, although I'm not a carb expert, I have a basic understanding that has allowed me
to successfully rebuild a number of Quadrajets over the years.
This is why I'm having a problem believing all the carburetors I've tried have a problem,
especially when at least two of them worked OK prior to my resealing and regasketing this engine.
This work included intake gaskets.
For obvious reasons, I'm reluctant to get into the chore of removing the intake until I've exhausted
all other possibilities.
The really perplexing part is all the different carbs I've tried have had different problems.
I guess this is the main reason solving this problem has gotten so drawn out.
I have other non-'67 carbs I could try, but, they've been on the shelf for a long time.
I may try them when I can get back to playing with the car.
Again, as soon as I receive the shim and install it, I'll post the result.
Thanks for all the good input.
As I've admitted before, although I'm not a carb expert, I have a basic understanding that has allowed me
to successfully rebuild a number of Quadrajets over the years.
This is why I'm having a problem believing all the carburetors I've tried have a problem,
especially when at least two of them worked OK prior to my resealing and regasketing this engine.
This work included intake gaskets.
For obvious reasons, I'm reluctant to get into the chore of removing the intake until I've exhausted
all other possibilities.
The really perplexing part is all the different carbs I've tried have had different problems.
I guess this is the main reason solving this problem has gotten so drawn out.
I have other non-'67 carbs I could try, but, they've been on the shelf for a long time.
I may try them when I can get back to playing with the car.
Again, as soon as I receive the shim and install it, I'll post the result.
Thanks for all the good input.
If, as RocketRaider suggested, the shim is not a shim, but actually a radiant heat shield, it would make some sense, but in that case, it would stick out well beyond the gasket flange, and, in fact, fastening it by clamping it under the carb would be a less than optimal way of mounting it.
Also, from what I can tell, your problem is not related to the kind of heat that such a shield would protect against.
Alrighty, then. You've tried harder than many would.
I would humbly suggest, in that case, that there is something wrong with each of those carburetors, and that that something is something that can be found and fixed, in at least one of them anyway, and that if you have the time and the patience, you might be able to do so without the help of so-called experts.
Ultimately, I would recommend buying or borrowing a cheap carb that is "wrong" for your car (something from a late-'70's pickup, for instance), but that works, and bolting it on, just to confirm whether your problem is related to the carburetor or not.
It's okay, I'm not implying that this is your fault, it's just that, man, this is a problem that's slow in fixin'.
Personally, considering the difference in difficulty between removing the intake manifold and removing the carburetor, I would strongly lobby for finding and installing a substitute carb. before embarking on a potentially fruitless hunt for an elusive vacuum leak.
- Eric
Also, from what I can tell, your problem is not related to the kind of heat that such a shield would protect against.
Alrighty, then. You've tried harder than many would.
I would humbly suggest, in that case, that there is something wrong with each of those carburetors, and that that something is something that can be found and fixed, in at least one of them anyway, and that if you have the time and the patience, you might be able to do so without the help of so-called experts.
Ultimately, I would recommend buying or borrowing a cheap carb that is "wrong" for your car (something from a late-'70's pickup, for instance), but that works, and bolting it on, just to confirm whether your problem is related to the carburetor or not.
It's okay, I'm not implying that this is your fault, it's just that, man, this is a problem that's slow in fixin'.
Personally, considering the difference in difficulty between removing the intake manifold and removing the carburetor, I would strongly lobby for finding and installing a substitute carb. before embarking on a potentially fruitless hunt for an elusive vacuum leak.
- Eric
Last edited by 67442nut; November 14th, 2014 at 09:55 PM.
November 14th, 2014, 09:54 PM
#36
Registered User
Join Date: Aug 2009
Posts: 333
Do you have manifold vacuum or ported vacuum to the vacuum advance?
There are many pie fights about which is the correct routing, but when I was tuning cars for a living, I found that some vehicles preferred one way, other vehicles the other.
I was tuning for emissions with good mileage and drivability, not strictly for performance, and won't get into that argument. But if you have manifold vacuum to the distributor, trying switching it to ported and see how things go.
There are many pie fights about which is the correct routing, but when I was tuning cars for a living, I found that some vehicles preferred one way, other vehicles the other.
I was tuning for emissions with good mileage and drivability, not strictly for performance, and won't get into that argument. But if you have manifold vacuum to the distributor, trying switching it to ported and see how things go.
November 14th, 2014, 11:49 PM
#37
Registered User
Thread Starter
Join Date: Nov 2007
Location: Charleston, West Virginia
Posts: 1,190
If, as RocketRaider suggested, the shim is not a shim, but actually a radiant heat shield, it would make some sense, but in that case, it would stick out well beyond the gasket flange, and, in fact, fastening it by clamping it under the carb would be a less than optimal way of mounting it.
- Eric
- Eric
It may be misleading to call it a "shim".
I only used that term because that's what the carb guy called it.
I guess functionally it's not a shim at all.
Describing it as a "heat shield" would be more accurate based on
the function of it that was described to me.
Do you have manifold vacuum or ported vacuum to the vacuum advance?
There are many pie fights about which is the correct routing, but when I was tuning cars for a living, I found that some vehicles preferred one way, other vehicles the other.
I was tuning for emissions with good mileage and drivability, not strictly for performance, and won't get into that argument. But if you have manifold vacuum to the distributor, trying switching it to ported and see how things go.
There are many pie fights about which is the correct routing, but when I was tuning cars for a living, I found that some vehicles preferred one way, other vehicles the other.
I was tuning for emissions with good mileage and drivability, not strictly for performance, and won't get into that argument. But if you have manifold vacuum to the distributor, trying switching it to ported and see how things go.
so I used a vacuum nozzle on the front of the carb.
I added a vacuum trunk release and the 700R4 transmission conversion.
Both required a vacuum source so I ended up using the available ports on the manifold.
There are some plugged ports in the manifold that are kind of difficult to access behind the carb.
I may try to remove those plugs to use for additional vacuum sources.
I've never actually compared the vacuum from the carb vs. direct vacuum from the manifold with a gauge.
November 15th, 2014, 09:40 AM
#38
Registered User
Join Date: Aug 2009
Posts: 333
A port off the from of the carb might be either manifold or ported vacuum. Check to see if there is vacuum draw from the port at idle (manifold vacuum) or when the throttle is increased (ported vacuum).
If it is manifold vacuum, try changing it to ported vacuum and see if the idle speed decreases enough to be able to dial everything in.
Be sure to watch for changing engine temperatures and performance changes. I've never found any real problems for a street car either way, but people swear it can make a difference. The biggest difference I've found is a change in idle speed and emissions; manifold vacuum results in increased timing at idle, which can sometimes cause fast idle that can't be corrected with the idle speed screw. Apparently in these cases, the carb is actually idling using the off-idle circuits. Exhaust gas analyzers often showed lower emissions, and once the engine was idling at slower speeds, the idle circuits would behave normally.
If it is manifold vacuum, try changing it to ported vacuum and see if the idle speed decreases enough to be able to dial everything in.
Be sure to watch for changing engine temperatures and performance changes. I've never found any real problems for a street car either way, but people swear it can make a difference. The biggest difference I've found is a change in idle speed and emissions; manifold vacuum results in increased timing at idle, which can sometimes cause fast idle that can't be corrected with the idle speed screw. Apparently in these cases, the carb is actually idling using the off-idle circuits. Exhaust gas analyzers often showed lower emissions, and once the engine was idling at slower speeds, the idle circuits would behave normally.
December 11th, 2014, 04:24 PM
#39
Registered User
Thread Starter
Join Date: Nov 2007
Location: Charleston, West Virginia
Posts: 1,190
Joe,
I finally got time to mess with the Cutlass again.
I've pretty much confirmed the intake manifold gasket is leaking.
I warmed it up and sprayed brake parts cleaner along the intake gasket.
The idle slowed temporarily at a couple of spots.
This, at least explains the fast idle problem, but, I still need to figure out the "running-rich" problem.
Talked to the carb builder again.
Told him I didn't use the full "turkey tray" intake gasket, just a pair of Mr. Gasket intake gaskets.
I thought maybe this could allow excessive heat to get to the intake/carb.
He also mentioned, using a ported vs. manifold vacuum connection for the vacuum advance.
If the advance advances too soon, it could cause the running rich problem.
Gonna take care of the vacuum leaks first with a new 'turkey tray", probably after Christmas.
December 11th, 2014, 04:34 PM
#40
Unfortunately problems like this require process of elimination efforts. Seems like the rebuilder is still grasping at straws.... I think though the vac advance at dist should be ported vacuum, need to check shop manual for that...
