http://youtu.be/HRwmFMs5_Z0


I am thinking this means weak springs? Whaddya think? 69 455 mixture was adjusted, no change. Timing at 6 degrees BTDC. Engine cuts off when I put it in gear too but I have not detected any vacuum leaks

 

timing seems low my chiltons manual say's 12 degrees btdc.

 

I think you are exactly right. Check out "scenario 9" on this page:

http://www.secondchancegarage.com/public/186.cfm

 

I think you need mor timing also. It also sounds like your idle is too low and fluctuating. Your video is kinda dark, so I can't see anything else. Spray some starting fluid on the back and front china wall of your intake.

 

Yeah I tried spraying carb cleaner all the way around the manifold and at the carb gasket. Engine speed never rose. When you say more timing you mean the timing needs to be advanced a bit? I had it at 8 BTDC now its at 6. Even when I had it at 8 it still did the same thing

I'm thinking my next move will be to replace the springs, then see how it acts. Grrrrrreat lol

 

I would set my timing for 34-36 deg BTDC @ 3000 with vauum advance disconnected, and then check to see where your initial winds up. With vacuum you want to be around 50 Btdc +/- @ 3000 rpm.

What carb are you running?

 

Stock QJET

 

Remember - If you DO have to replace your springs, you CAN do it without removing the heads or the intake.

- Eric

 

that is a great site for checking vacuum.
Check this pdf out too.

 

That's right. I did my valve seals with no issues. The right spring compressor ($20 at local parts store) and compressed air in the plug holes makes it easy.
Here's my little procedure...
https://classicoldsmobile.com/forums...tml#post317189
The reassy one is down a bit...

 

Your initial timing should be around 12-14 degrees...once you get your timing set right, then you should adjust the carb. Like it was mentioned above, remove your vacuum advance and plug the vacuum port on the carb. Rev the engine to 3000 rpm and see where your total is. My guess is it's somewhere around 26 degrees with the way you have it set right now. You should have between 30-35 degrees total timing. Loosen the distributor, rev the engine and set the distributor to 30 degrees as a start. Then check your initial again...make small changes from there and see how it runs. I don't see valve springs as being weak, not at idle. I think you'll notice a problem above 4000 rpm if they are, but not usually at idle. I vote check timing, the problem is in your tuning.

 

I'm thinking carb has worn throttle shafts - see if it moves over .005 by hand!

 

OK,
I'm gonna go out there now and set the initial timing to 14 and see how it runs. I don't have access to any timing tape right now so I can't set it to 36 unless somebody knows another way to do it. Open to any suggestions. I'll grab the throttle shaft too and see how it feels.

 

Do you have an adjustable timing light?

 

It's no fun to reach in there and mess with the balancer and timing tab. but if you can reach, set the balancer where you can see the line, use a piece of paper or something similar to measure a known distance along your timing tab (some are marked at 5° and 10°, some are marked from 0° to something like 16° or 20°), then transfer that measurement to your balancer, measuring from the TDC line, to get to the graduations you want (you can go by 2s, 5s, 8s, 10s, whatever). Mark a particular line as your target so it's easy to see, then just line it up with the right mark on the tab.

- Eric

 

OK,
I got it at 16 and it idles at 900-1000. I tried it at 14 and it went down to 850-950. Vacuum is still all over the place (0-10 at idle or 10-20 at 2500) I got the mixture screws turned in all the way and about 1 turn out each. If I turn them out about another turn, then I can smell gas. I maybe could turn the slow idle out to turn it down a notch. Maybe it is a vacuum leak somewhere but I put a new intake on there (With it on the stand, so I could get to it all pretty easy and made sure I had everything sealed) so I don't think it's that. I might do a compression test if I can find my compression gauge. That way I can at least know how everything is sealing?

One other thing is even of I hook my distribitor up to vacuum at this rpm the advance doesn't kick in. I got it hooked up to the drivers side port on the front of the Carb. Maybe I should hook it up to manifold vacuum? Hmmmmmmmmm

 

Set your timing at 14 degrees initial...then adjust the carburetor to obtain the desired idle speed. As far as the vacuum advance on the distributor...it should be connected to the manifold vacuum port on the carburetor or the manifold itself.

When adjusting the idle air mixture screws take them all the way in, then turn them out 1/2 turn each until you get a rough idle...then turn them back in 1 whole turn...IIRC.

 

Also, let's get into this a little more...

What carburetor do you have, what cam, give us more detail about your engine. It sounds to me like you've got some lope to your cam.

 

Not sure on the cam. I bought the engine off Craigslist. It'll idle at 850...barely. but as soon as I put it in gear it idles down so low I have no vacuum (No brakes lol) and I have to hit the gas pedal or it cuts off. Then if I adjust the idle so it's high enough for the engine to keep running if I put it in gear, when I do put it in gear the car jerks more than I want it to. Now once I get going it's fine. Enough vacuum for brakes, etc. But when I slow down for a stop light right before I stop completely the brakes get really hard (Cause I have no vacuum at that point) and the car acts like its about to cut off unless I hit the gas pedal.

Maybe I'll just have to idle it around 1000 rpm so it won't cut off once I put it in gear. Which I am trying to avoid. Sigh lol...

Carb is a 70 4 barrel Qjet
I DO have a dial gauge where I could measure the valve lift to try to see what kinda cam I got. I have had it for a while but never used it so I'm not sure how accurate it would be. I think i tried before but I couldn't find a decent spot to mount the magnetic stand to get an accurate reading. And this was with the engine on the stand.

 

JMO, the way the car sounds in the video that engine has a fairly large cam in it. If you've got the timing set at 14 degrees now and it still wants to die when you put it in gear you may want to do just that...check the cam to find out what it is. If it's a fairly large duration cam you would have the same vacuum readings, low at idle and moderate at RPM.

My car acts the same way as far as braking goes. I have a booster and extra canister and the only time I get any help is at first braking application when coming down from RPM. In traffic I essentially have no power brakes. My cam is 244/252 duration at .050"...you may have a similar cam, in which case your car is going to have to be tuned differently than a stock engine.

 

20* advance timing! It's not a Chevy

 

Ah64pilot,
Thanks for the tip! I may very well have to figure out the cam lift to see what kind of cam I got in it. I think in the short term I'm gonna try advancing the timing more and then seeing if I can back the slow idle screw off and see if that slows it down a bit.

I'll try checking the cam as a last resort

 

I had a 284 duration .505 lift on a 108 centerline, and although 'lumpy', idled smooth!
I adjusted the carb/timing like this;
Unplug vacuum advance, and install vacuum guage
idle @ 1000 rpm
Timing @ 12 degrees
adjust carb mixture screws to highest vacuum obtainable, while turning screw in
Bring idle to 850
unplug guage, install vacuum advance
re-adjust idle rpm

You've mentioned nothing changes when you plug in the vacuum advance, IT'S NFG!
Get a new one - big vacuum leak there!!
You never mentioned if you checked the throttle shaft -they're notorious for going bad!
Did you check the mechanical advance under the rotor? Should move smoothly by hand!
I'll bet money it's a vacuum situation - - - - - -

 

If you look at my video link you can see what my current vacuum is reading. At idle 0-10 and when I rev it from 10-20. But it's nowhere near steady lol.

I'll have to check my throttle shafts. But here is the thing. Even if I have the vacuum disconnected from the distributor, it still won't idle at less than 900.

I CAN get it to idle at 1,000 (With the vacuum disconnected from the distributor) But once I plugin the vacuum to the distributor should that make it drop down further? At idle?

 

I know what I'll do. I'll set it to idle at 1,000 with the vacuum disconnected from the distributor. Then once I got that I'll pull vacuum on the distro using my vacuum pump and see if it'll idle when I put it in gear then.

How much vacuum should I have at idle? If hooked to the manifold I thought vacuum goes down when you accelerate, and if its hooked up to the carb (Above the throttle plates) you get no vacuum at idle then a bunch of vacuum when you are accelerating?

Maybe I need to hook the distributor vacuum up to the manifold? I'll try that tonight too.

Luckily it's a beautiful day here in BaileysCrossroads (Northern VA)

 

The vacuum advance should increase the rpm, when plugged in!
GET A NEW ONE!

 

Ok. But the port I have the distro connected to isn't giving any vacuum. I'll try connecting the distro to a port with vacuum and see how it acts. I was connecting it to the drivers side port on the front of my qjet. I think I'll try connecting it to manifold vacuum and see what happens

 

You should definitely check the diaphragm with your vacuum pump.
First see if it pumps up all the way, that the plate moves when pumped up, and that it holds in place (doesn't leak).
Then check to see how much vacuum it takes to first move it, and how much when it's completely pulled in.

If it's good, see whether hooking it to direct manifold vacuum helps your symptoms.

The potted vacuum does NOT go up with acceleration. At all.
The potted vacuum starts at zero at idle, then immediately rises to where the manifold vacuum is as soon as you start to open the throttle, and stays the same as manifold vacuum throughout the rest of the range.
The only place where it's different is at idle, with the throttle plates closed.

- Eric

 

"ported"
I meant "ported"

Damn autocorrect.

 

Did you get a book w/ the vacuum gauge? This tool IMO is one of the best things to use in trouble-shooting your engine, or to make adjustments, etc. If you have some experience w/ the gauge, and know how/what to look f/, in the correct sequence, it can tell you SO SO many things. Mess w/ it for awhile and get used to it, or if you know someone who's near by and who is good w/ the gauge, get that person to help you use the tool correctly. It really does take some experience and know-how to use a vacuum gauge to it fullest. This tool IMO is one of the very best, especially if you have an all-mechanical set-up, non-computerized, but is still great w/ the newer models.

Seems that you've messed around w/ the gauge quite abit, just make sure that you're going about it in the correct sequence. Is the cam keeping you from a lower idle RPM due to it's profile? Any small idle ports in the carb clogged? Only takes one. What are the plugs telling you? The color, all evenly colored, etc. The plugs can tell you a big indepth story if you know how to read them. Good luck. I'd get a new set of plugs and start the reading from there.

 

Stop, timeout!!!! In my humble opinion you have a pretty lopey cam in there and have no idea the specs of the engine! What distributor are you running, points or electronic? Brand?

Get an adjustable timing light!!

Make sure your plugs are gapped correctly. If you have points, set your dwell to 30 no more, no less. Turn the adjustment on the timing light to 34*. Set the timing with vacuum advance disconnected to 0* on the timing tab at the RPM at which the mechanical advance stops. This will get your initial timing to where the engine was originally tuned and note the setting at 850 RPM.

Then hook your vacuum advance up and repeat the high Rpm check and note at what rpm your timing stops. Then at that RPM, adjust the timing light, not the distributor so the line on your balancer lines up at "0" on your timing tab and note that setting. It should read somewhere around 50* +/- on your timing light.

After this proceedure your timing should be in the ballbark. Then adjust your carb. for highest vacuum or rpm at around 800. After you have your Air/ fuel adjusted set your curb rpm 750-850 in drive and see if it will stay running in gear. At this point you can incrementally drop your idle speed to where it will idle in gear.

Please get back to us with those readings.

 

Ok,
I just heard from a buy on Craigslist that has an advance timing light for sale for $20. Im gonna go pick that up after work today. Once I get it I'll try what you suggested and go from there.

I'm running a stock HEI

Thanks!
Bunyan

 

You might be able to rent or borrow one from your local parts store also!

Gap plugs to .045.

Like I said above that will get your tune close.

Don't do anything with your springs yet.

One more question, have your rockers been converted to adjustable type or do you still have the standard rocker/perch type?

 

Standard rockers

 

From what I can tell by the video the engine runs pretty good. But, I could not tell if any of them clatter?

 

No clatter. Runs perfect except for it cuts off if I have it in gear and come to a stop. If I set the idle high enough to prevent that (1000 rpm) when I put it in gear it jerks more than I would like. But when I idle it down to about 850 it cuts off. My problem, in a nutshell

 

Curious, what transmission and torque converter are you running? Did this setup come as a package with your engine?

We will tackle the in gear issue after we get the motor setup.

 

"No clatter. Runs perfect except for it cuts off if I have it in gear and come to a stop. If I set the idle high enough to prevent that (1000 rpm) when I put it in gear it jerks more than I would like. But when I idle it down to about 850 it cuts off. My problem, in a nutshell"




That sounds like a vacuum leak. Check the obvious: hoses, connections, gaskets etc. I would also check the master cylinder booster. Disconnect it and see if anything changes. I had a cracked plastic connector on my Toronado that only allowed it to shift at WOT. After dropping the pan and replacing things ^&#%@^$ I finally found it. 69 cent brass T fixed it. Basically check anything that draws vacuum from the engine, no matter how small or large.

From your video it does look like worn valve springs but from your description it sounds like a vacuum leak.

 

Thanks for the advice. I am thinking this may be it too (Vacuum leak) but I am not sure. I will try blocking all vacuum ports and checking the vacuum then once I get home. I already tried spraying all around the manifold/carb gasket and seeing if the RPM increased and it did not.

 

All,

Problem was my carb. The emulsion tubes came out. Look at the red circles in this pic

I got them back in, but then broke off one of the ears holding the float pin, so I broke down and ordered a new carb. Should be here Wednesday or Thursday. Thanks for all the help/suggestions