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Base Timing (Setting without Vaccum Advance):
15 Degree @ 1200 RPM
If i connect the Vacuum (Point Distributor), i have 34 Degree @ 1200 Rpm
My problem is that i have sometimes Idle Drops (mainly with warm Engine) from approx 900 Rpm Idle
to 400 or less by shifting into D or R, or steering Left / Right (with Powersteering) at a Stop Light
and Parking maneuvers are always nerve wracking.
Any inputs why or what i could do?
- Wrong Timing Advance?
- Wrong Carb?
- Torque Converter?
I have no experience with using a vacuum canister along with a vacuum advance distributor. How does the distributor vacuum canister get connected in that system?
I have no experience with using a vacuum canister along with a vacuum advance distributor. How does the distributor vacuum canister get connected in that system?
Hi Fun71.
The Vaccum Canister is between the Intake Manifold and the Brakebooster, supporting the Brakebooster only!
You can find Videos how to install on Comp Cams or Youtube.
It helps alot if you have a Big Cam (Lobe Separation under 114) and weak "Brake" force.
Was the cam degreed when the engine was built? I assume the AVS2 has generous idle fuel capabilities? As said, check your vacuum idiling in gear. You could try a ported vacuum source for vacuum advance. Your idle vacuum in gear may be low, I would bump it to 1000 rpm in park to start. Good luck.
Was the cam degreed when the engine was built?
- I set it to 0 Degree, as far i remember I assume the AVS2 has generous idle fuel capabilities?
- Should have so.. As said, check your vacuum idiling in gear.
- Check attached Picture.. i got a few facts together today. You could try a ported vacuum source for vacuum advance.
- I have as always in the Ported Carb Connection (Edelbrock Front, Left Plug) Your idle vacuum in gear may be low
- as i wrote.. unexpected drop from 1000 to 400rpm, to set a idle around 800 is not possible at to moment. I would bump it to 1000 rpm in park to start.
- this is the only way i can drive at the moment.. Good luck.
Readings are all done in "Park"
Thanks for all Inputs.
Could it be that i need more Advance Timing approx. 16-18 @1200Rpm (as Base Setting / no Vac.Advance connected for adjustments) ?
when the engine drops form approx 1000rpm to 400 Rpm the Vacuum Gauge Jumps between 0 & 7 in/hg very fast and the engine almost shots off or even does.
Or is it the Carb "Modification" see picture.
Edelbrock AVS2 (1906) 650 CFM (+ Tuning Additional 0.04" Holes on all 4 Throttle Pates)
I assume that timing chart is with vacuum advance connected? But being a points timing curve, is it? That 46 degrees, without vacuum advance would be too much. You could experience detonation. You could try to add another couple of degrees of base timing and try manifold vacuum for your vacuum advance, it may help it idle. 8 degrees is pretty low vacuum. If your cam timing was verified with a degree wheel, it will be fine. What brand of timing chain did you use?
Last edited by olds 307 and 403; July 16th, 2022 at 05:16 AM.
I assume that timing chart is with vacuum advance connected?
The Left Chart is all without Vaccum Advance (Degree with NO Vacuum Advance)
The Right Chart is all WITH Vaccum Advance
But being a points timing curve, is it?
Its a Point Distributor (NEW)
I`m not shure if i understand your question correctly, sorry.
That 46 degrees, without vacuum advance would be too much.
Its the Right Chart, so its 2700RPM / 46 Degree WITH Vacuum Advance connected to the Ported Plug of the Edelbrock AVS2 650CFM.
You could experience detonation.
i hope not.. all okay at the moment
You could try to add another couple of degrees of base timing and try manifold vacuum for your vacuum advance.
Base Timing is now 14.8 Degree (15 degree) @1200 RPM (without Vacuum Advance Connected).
Ported or Manifold.. i never had good experience with Manifold Vacuum connected to Vacuum Advance of the Distributor.
what do you think of this Video about Ported or Manifold YOUTUBE:
8 degrees is pretty low vacuum.
Well Yes on the Left Chart its 1000 RPM with 12.6 Deg & 8 In/Hg (No Vacuum Advance Connected)
same RPM on the Right Chart, i have 1000 RPM with 27 Deg. & 12 In/Hg (with Connected Vacuum Advance) Question: How much In/Hg should i have at 1000 RPM measured without Vacuum Advance Connected?
If your cam timing was verified with a degree wheel, it will be fine.
okay. welll its not verified. "here im lost" i got that cam without any "CAM CARD" only facts i had or still have
are the one i had on a sticker of the box. See Cam Specs on the First Post
As i can remember i pined it down to 0deg. no extra edits cause had no facts or dont know how to calculate it out of the specs i have.
Other than a low idle, how does it run and drive? It should be 10+ inches of vacuum at idle, that isn't that large of a cam. Little things like the mixture screws adjustment and more timing will increase idle vacuum and stabilize the idle. Manifold vacuum should boost timing and hopefully help stabilize your idle. I hope that Speedmaster timing set is accurate.
My car did this and it came down to advance springs you may be advancing at idle and when the engine slows down it cuts back the advance. Instead of doing two light springs I did 2 medium springs. The advance snaps in about 1000 and all in by 2500. 14 initial and 22 mechanical. This is with a 10.25 to 1 solid lifter cam on my current 355. It idles about 900 and in drive it will be 700 to 750. Have someone check the timing at idle then drop it in gear and see what the timing does.
What do you mean when you say cam was at 0 degrees?
Chain looks loose. Is that a matched set? Check your ignition timing before you put it into gear then afterwards as well. Let us know what that turns out to be and we’ll go from there.
Another thing to consider is if too much of that transfer slot is exposed and your base timing is set to compensate for that fat idle once the engine slows down from putting it in gear the idle quality will suffer. You combination should work well with a 3310 Holley. The stock 3310 Holley worked for me very well in a similar combo. There is better but for the price it works well. As for the timing chain it does look a bit loose but degreeing it should tell you if it's really off.
Other than a low idle, how does it run and drive?
- Well it drives nice.. 3.08 Rear End is def. not the best (something like 3.5 would be nicer) but the engine runs and goes good from 2500 to 3700 RPM. I didnt push more RPMs at the moment.
On the highway with constant 60Mph the 3rd Gear of the TH350 drops out after a while, and i have to push the Gas Pedal / the Rpms to get it back in 3rd Gear so it holds again for a 1 minute. This must be something with a Vaccum drop and RPM Level / Manifold Vac. & Modulator of the Th350 Transmission. I will try my "Black & Red" coded TH350 Modulator (Low Vac Modulator)
It should be 10+ inches of vacuum at idle,
- I have 11 In/Hg at 1000 Rpm, approx. 9 In/Hg at 730 Rpm, lower than 700 Rpm the Vacuum Gauge Needle is jumping from 0 to 5 In/Hg
Little things like the mixture screws adjustment and more timing will increase idle vacuum and stabilize the idle.
- I have a Emission Control Maschine with %Vol CO & ppmVol. HC and i adjusted the «idle» mix with approx. 4 %Vol CO on both sides.
i dont remember the "ppm Vol. HC"
Manifold vacuum should boost timing and hopefully help stabilize your idle.
- Yes.
I hope that Speedmaster timing set is accurate.
- I hope that too..
Thanks for all in Inputs!
Last edited by Nic_The_Cutlass_Guy; July 24th, 2022 at 02:14 AM.
My car did this and it came down to advance springs you may be advancing at idle and when the engine slows down it cuts back the advance. Instead of doing two light springs I did 2 medium springs. The advance snaps in about 1000 and all in by 2500. 14 initial and 22 mechanical. This is with a 10.25 to 1 solid lifter cam on my current 355. It idles about 900 and in drive it will be 700 to 750. Have someone check the timing at idle then drop it in gear and see what the timing does.
My car did this and it came down to advance springs.
- Very very interesting
you may be advancing at idle and when the engine slows down it cuts back the advance.
- Yes.. if i check my Timing Sheet of July 15th (check post) a have doubling of the advance at 1000RPM.
Instead of doing two light springs I did 2 medium springs.
- I will try this out.. i have a MSD Springs Kit somewhere .. i hope they fit that «Stock Point Distributor.
Anyway. I have to change this Stock Distributor aswell, any suggestions that work fine with Olds and parts are available the next 5 years.
MSD Part # 8529? Or others ?
The advance snaps in about 1000 and all in by 2500. 14 initial and 22 mechanical.
- Sounds good!
This is with a 10.25 to 1 solid lifter cam on my current 355. It idles about 900 and in drive it will be 700 to 750.
- I would love to copy this..
Have someone check the timing at idle then drop it in gear and see what the timing does.
- Right, i will work on it!
Thanks for you input!
What do you mean when you say cam was at 0 degrees?
Chain looks loose. Is that a matched set? Check your ignition timing before you put it into gear then afterwards as well. Let us know what that turns out to be and we’ll go from there.
What do you mean when you say cam was at 0 degrees?
- I tryed to aligne to S mark of the Camshaft Gear to the «Dot» of the Crankshaft Gear.
- i wasn`t gambling with any Advanced / Retarded Degrees on the Camshaft Gear.
- i didnt get any «Cam Card» just a sticker on the Box, so i was requesting it serval times from the person who sold it to me and the manufactorer.
Now, after almost 2 Years i got it, but the Engine is already in the car and yeah.. we will see..
Chain looks loose. Is that a matched set?
- I hope that its a matching set!
- It was fresh out of the Box and the Seller said it fits my 64`Olds 330Cui Engine.
Check your ignition timing before you put it into gear then afterwards as well. Let us know what that turns out to be and we’ll go from there.
In and after stayed the same, i couldn`t check timing in Gear (Idle = let say i have 2 Idles 1200RPM & 380RPM at the moment) Cutlass Timing Sheet July 23rd 2022
Its a fight to get any measurements with a connected VAC Adv. on Ported Plug of the Carb. between 1200 Rpm and Lower.. the Engine / Carb is so sensitive if adjusting Idle RPMs.
its like 1200 RPM solid or 380RPM chopping Solid.. all between is a fight to have it sold.
I never had this in the beginning (during Engin Break-In Phase, first 600Miles)
Maybe somewhere around the Vac. Advance of the Distributor, Springs, Leak, damaged ?
Thanks for all your Input!
Last edited by Nic_The_Cutlass_Guy; July 24th, 2022 at 02:40 AM.
As Copper said, your timing needs to be stable at idle and below.
Yours drops drastically. Something with the weights or springs is mismatched. Check carefully for wear on the pivots and weight holes. Check that the advance springs are tight.
If you know someone with an old-fashioned Sun Distributor machine, it's easy to find the problem. Otherwise you need to use old-fashioned problem solving.
As the idle speed falls when you put it in gear, the advance falls also. That drops the idle speed further, which drops the advance further. This is a feedback loop that drops your idle speed until these things balance to make it stabilize at a much lower speed...
The timing becomes stable (below about 500 rpm)
The engine load reduces at the new, lower idle speed
Hi Gary,
Thanks for your Time and Input to my problem!
So i will scan my Points Distributor for Errors tomorrow.. try to change the springs to a pair of "Stronger" ones aswell.
and get me asap a
"Small Cap OLDSMOBILE 330, 350,400,403,455 BLACK HEI Distributor w/45K Coil"
One other thing stands out, Nic. Your vacuum can is adding to the negative feedback loop (as idle drops, vacuum advance timing drops).
Your vacuum advance can needs to be one that will maintain its advance at idle vacuum.
As an experiment, get a different can that will stay active at around 8 inches. Try a NAPA/Echlin part number VC1810 (AutoZone DV1810). That can will hold full timing down to the 6 to 8 inches range. If you get pinging under light load, you'll need to compromise a bit and get a less aggressive can.
Hi Gary,
well.. that sounds interesting!
So you say i should try other Vac. Advance "Cans" that don`t "pull / react" under 6-8 In/Hg ..right? there are Adjustable "Vac. Advance Cans".. would this be aswell a solution instead of buying 1-3 different ones?
Only that i get it right with this "Loop Problem".
finally i need to sort / break this Loop by having a "Vacuum Advance" that doesn`t kick in under 1000 RPM, so that i have between 500RPM and 1000RPM only Mechanical Advance from the Distributor.
I can handle this problem by changing the Springs on the Distributor with "tougher Springs" or a "Vac. Advance Can" that
starts reacting above 8 In/hg. right?
I have a few other older Point Distributors somewhere (1968 & 69`Buick Skylarks) maybe i can flip the CANS over for a test too if the fit..
As more the focus goes on this "Distributor" as quicker i wanna get rid of that "shi.. Point Thing"
do you think a MSD Dist. Part # 8529 is a good way to go? its very expensive if i calculate shipping & Taxes etc. on top..
it looks like there a few good options to make adjustments if needed.
Big Thanks to each and everyone for your help!
Last edited by Nic_The_Cutlass_Guy; July 24th, 2022 at 03:57 PM.
You need to get a vacuum can that KEEPS vacuum advance at idle, even if the idle vacuum drops to the 6 to 8 inch range.
Yes, you could buy an adjustable vacuum can. Just be sure it can hold advance at 6 to 8 inches.
The can should reduce timing only when the vacuum drops lower than 6 to 8. That means when you open the throttle and want power, the vacuum advance needs to go to zero. If the can doesn't drop vacuum fast enough, you will get pinging or knock.
This solution is something to try separately from springs. Both could have a favorable effect on your problem.
Your Buick distributors have vacuum cans that are interchangeable with your Olds distributor. Use the numbers stamped into them to look up their specs before you try them.
You will need to tailor the timing in an MSD 8529 distributor the same as we are discussing. It's only advantage is that it is prettier than your current distributor. It's no less work to dial in.
Don't be put off by the potential solutions you could be trying. They don't cost much and just need a little thought to evaluate them.
You are very good at recording data, better than 80% of the usual suspects. That part is the most difficult for most, so you've got a big leg up there.
There are always many on here who will share knowledge, so keep working at the problem.
You need to get a vacuum can that KEEPS vacuum advance at idle, even if the idle vacuum drops to the 6 to 8 inch range.
Yes, okay i got it thank you! 1970s Cars & upwards have vacuum delay valves, could this be useful..
Yes, you could buy an adjustable vacuum can. Just be sure it can hold advance at 6 to 8 inches.
Great!
The can should reduce timing only when the vacuum drops lower than 6 to 8.
Yes i understand.. so around 1000 RPM downwards it should release the In/hg
That means when you open the throttle and want power, the vacuum advance needs to go to zero.
And here is something i don`t understand.
If i accelerate very quick (Break Away Performance), the Ported Vac. should support the Advance Timing and not taking it away by falling down to Zero.. isn`t it?
or will the mechanical advance Save this Drop?
This sound almost like Manifold Vac. connected to Vac. Advance Can.
Or ist there a different behaviour on the Ported Vac. on Quick Acceleration and smooth Acceleration.
If the can doesn't drop vacuum fast enough, you will get pinging or knock.
Okay.. sorry.. i have to get to understand this. But i will soon, i think i see the "light"
Thanks for your patience. "If the can doesn't drop vacuum fast enough" = it would Add to much Mechanical + Base?
This solution is something to try separately from springs. Both could have a favorable effect on your problem.
Okay
Your Buick distributors have vacuum cans that are interchangeable with your Olds distributor. Use the numbers stamped into them to look up their specs before you try them.
Yes i will check them before!
You will need to tailor the timing in an MSD 8529 distributor the same as we are discussing. It's only advantage is that it is prettier than your current distributor. It's no less work to dial in.
Okay.. i like my «Black Pointer» design more than screaming Red MSD. Hahaha. but i will change it to HEI.
Don't be put off by the potential solutions you could be trying. They don't cost much and just need a little thought to evaluate them.
Never! I stick on it like «John Rambo» i will get there, with all you supporters around here.
I`m Thankful all day.
You are very good at recording data, better than 80% of the usual suspects. That part is the most difficult for most, so you've got a big leg up there.
Thanks Boss!
There are always many on here who will share knowledge, so keep working at the problem.
I appreciate that very very much!
Good info. Of course most factory mid 70's to 80 Olds HEI usually run much less mechanical advance, usually had 20 degrees base timing. That alone would greatly improve idle vacuum, just add an adjustable vacuum advance. As said the MSD distributor with the black mechanical advance bushing installed would allow similar base timing and also have an adjustable vacuum advance. Most aftermarket adjustable vacuum advance cans only have 20 degrees max and can be adjusted to almost 0, if needed.
I'm a bit multi-tasking and prepairing for the next tests.
i thought i will test to drive the car only with Mechanical Advance, so no Vacuum Loop or things should interrupt.(right?)
Then i went thru the Edelbrock AVS2 Manual about Adjustements / Trouble Shootings, so i found this LONG DURATION CAMSHAFT on Page 8.
It describes very much my problem too. "poor levels of Adjustability & erratic Idles"
Just to understand this "Fix" that Edelbrock delivers here.
Does that mean that, if i wanna drive it without "Vacuum Advance", only with Mechanical Advance.. i need softer springs (Mechanical Curve) inside of the Distributor to have more "Advance" at early RPMs like 500 RPM?
Is this aswell the reason why i need 2 1/4 Turns on the "Idle Speed Screw" (that opens the Throttle Plates) to have a minimum Rpm that can start the Engine and hold it. (400 RPM with no connected Vacuum Advance)
Edelbrock Carburetor AVS2 Manual - Page 8
Last edited by Nic_The_Cutlass_Guy; July 26th, 2022 at 11:02 AM.
You could try lighter springs, it may help. The two distributors along with others, can add more initial timing at idle. The MSD isn't cheap but it's size matches your points distributor and is fully tunable for the initial and advance curve. The Chinese aftermarket HEI have similar curves to your current points distributor. Yeah, a 400 rpm idle is pretty low, does it stall out sometimes?
It should be 10+ inches of vacuum at idle,
- I have 11 In/Hg at 1000 Rpm, approx. 9 In/Hg at 730 Rpm, lower than 700 Rpm the Vacuum Gauge Needle is jumping from 0 to 5 In/Hg
Little things like the mixture screws adjustment and more timing will increase idle vacuum and stabilize the idle.
- I have a Emission Control Maschine with %Vol CO & ppmVol. HC and i adjusted the «idle» mix with approx. 4 %Vol CO on both sides.
i dont remember the "ppm Vol. HC"
That means when you open the throttle and want power, the vacuum advance needs to go to zero.
And here is something i don`t understand.
If i accelerate very quick (Break Away Performance), the Ported Vac. should support the Advance Timing and not taking it away by falling down to Zero.. isn`t it?
or will the mechanical advance Save this Drop?
This sound almost like Manifold Vac. connected to Vac. Advance Can.
Or ist there a different behaviour on the Ported Vac. on Quick Acceleration and smooth Acceleration.
Nic, when the engine is at part load, it can use a lot of extra advance to increase fuel economy. The vacuum advance canister provides that extra timing.
But vacuum advance must go away when you want power. Both ported vacuum and manifold vacuum do this.
When you suddenly accelerate, the timing requirement of the engine falls drastically. The distributor provides this drop by eliminating vacuum advance. Mechanical + base timing governs under max or near-max acceleration--that's the most timing an engine under load can use without knock.
Ported vacuum has zero signal when the throttle blades are in the idle position. Ported vacuum’s purpose is to reduce emissions at idle by providing a false load on the engine.As you start to open the throttle blades, you begin to get a vacuum signal and you get ignition advance from the vacuum advance can.
Off-idle, ported vacuum acts identically to manifold vacuum.
Manifold vacuum provides a signal to the vacuum advance can regardless of whether the throttle blades are closed.
At off-idle, ported and manifold vacuum act identically. There is no difference in how they react to acceleration and no difference in their signal.
If you open the throttle blades suddenly from idle position...
ported vacuum signal stays at zero (zero at idle and zero at full throttle).
manifold vacuum signal drops to zero (high at idle and zero at full throttle).
If the can doesn't drop vacuum fast enough, you will get pinging or knock.
Okay.. sorry.. i have to get to understand this. But i will soon, i think i see the "light"
Thanks for your patience. "If the can doesn't drop vacuum fast enough" = it would Add to much Mechanical + Base?
Exactly. To avoid knock during heavy acceleration, vacuum advance timing needs to go away. The mechanical + base timing is all the engine can tolerate under that condition without pinging or knocking.
Okay, Todays Journey was as following.
I went to the Car and reset the Edelbrock AVS 2 Carburetor to «Lets say, out of the Box Settings». I took of all Vacuum "users" from the Carburetor and closed these ports with those Rubber Caps.
(Vacuum Advance, PCV, Manifold Vacuum)
So i turned the Idle Mix Screws (Left & Right) clockwise back in till Stop and then 2 Turns Out again for the beginning.
I did the same with the Idle Speed Screw. I Turned that Screw «outward» till the end of the Screws Tip barely touches the Throttleplate Linkage and checked aswell if the «Fast Idle Linkage» is not holding the Throttleplates open.
Then i Turned the Idle Speed Screw 1 Turn In.
I changed the Distributor Springs to the Lightes possible setting (MSD Springs - Silver Light & Silver Light)
Then i gave it the first try and i could not start the Engine with the «Idle Speed Screw - 1 Turn».
So i tweaked the «Idle Speed Screw for 1 more turn = 2 Turns Total»
I Started the Engine and it was on the edge of holding on. So i gave a little ¼ Turn more on the «Idle Speed Screw = Total 2 ¼ Turns»
and it Startet and kept holding on, on a very very low 380 RPMs.
1st. Fact - The Car did not Start & Hold under 2 ¼ Turns of Idle Speed Screw.
So to get a bit more RPM i needed again more «Idle Speed Screw Turns» .
At around 850 RPM i was checking if some Idle Mixture Screwings would help me now.. But there was nothing, no reaction of the Engine or Vacuum.
I turned them «Inwards» till Stop and the engine was still running "easy" with no signs of anything. I turned them Out again, each up till 4 Turns.. Nothing...
2nd Fact - Idle Mixture Screws don`t react at 2 ¼ to 3 Turns of Idle Speed Screw Turns anymore.
Cause of the exposed "Transfer Slots" by the Primary Throttle Pates ?
3rd Fact – Not possible to adjust a solid Idle.
So i took the Carburetor off and checked the Primary Throttle Plates with (2 ¼ Turns on Idle Speed Screw) by far to wide open!
Then i opend the Carburetor to check all 4 Jets, Rods, Step Up Springs, Pump & Re-Adjusted the Floater Levels and cleaned it.
I put it back on the engine again.. and there was no change...
Question:
what causes this problem that i can not get or keep the Engine running without «Bypassing» the Idle System with approx. 3 Turns of the Idle Speed Screw.
- Carburetor Damaged?
- More Advance Timing?
- False Total Timing setting? 34@3500RPM (i have no infos by the manufactorer of the camshaft)
- Shifted Timing Marks @ Balancer
- Degree Check / Timing Chain (Back to Square One)
Last edited by Nic_The_Cutlass_Guy; July 27th, 2022 at 02:10 AM.
What was the purpose of drilling the smaĺl holes in the throttle butterflies? Could those be causing your idle problem.
Hi
some said it could help @ Idle if you have a rougher Camshaft. so i gave it a try.
at the moment i closed them again / changed them back to Stock Throttle Plates. (closed)
Are you sure you don’t have a large vacuum leak. Are the HCs on your analyzer high. Does it give O2 readings? High Hc and High O2 readings indicate a lean mixture. I have seen vacuum leaks big enough that the mixture screws do very little.
Are you sure you don’t have a large vacuum leak. Are the HCs on your analyzer high. Does it give O2 readings? High Hc and High O2 readings indicate a lean mixture. I have seen vacuum leaks big enough that the mixture screws do very little.
Hi Gary
The % Vol CO was around 4 but i don`t remember the ppm Vol HC..
i will check asap again and take a photo or write it into my Timing Sheet .
I found a Photo.. but im not 100% Shure if its my Cutlass or a other Car i was working on.
but the RPMs could say so.
could be my 1964 Cutlass
Thanks for your Input!
Last edited by Nic_The_Cutlass_Guy; July 28th, 2022 at 01:46 PM.
sorry for the delay!! Alot of things beside my car happend over the last view days.. so well, here we go....
i think i found the problem.
After a few more fails & try outs, starting with the Harmonic Balancer "Slip" check, or maybe false "Timing Marks" on the Balancer or the aftermarket "Timing Tab", cause i have a 1964 Engine and use a 65` Waterpump, so it needs 1965 Timing Tab.
Side Note: 1965 Waterpump has the inlet on the "Right" side, The 1964` Waterpump on the Left. So i had to get a other "timing tab" back in 2020, cause the 1964 would be underneath the Waterinlet if you choose to go with a 1965 & upwards Waterpump. The Balancer has to be one that has the TDC matching to this Waterpump situation & Timing Tab to read the correct timing..
Anyway, hours later.. all "Could be`s" were good.
Then i took the carburetor off again and inspected only the Idle circuit and cleand it "again"... i took some airpressure, brake-cleaner & a mircro-brush..
got it back on the car again and there was stiiiilll the same problem..
So i took my NEW quick "CO Tester" (Gunson G4125) to see in what "CO Range" i am with all of these problems... it showed a CO of 6.8 !! to "Rich" ..
I tried the idle Mixtures Screw again, but no big changes... so then i got a bit Angry and took a Spray Can of Brake - Cleaner and sprayed (flooded) the Intake allover, aswell on Bolts & Vac Links i didn`t expected it could be a problem..
THEN!! there was a reaction, so strong the engine turn off.. THE REAR MANIFOLD BOLTS (see Pictures), underneath the Iginition Coil and opposite too..
They were tight.. approx 25 LBS/ft but they Sucked AIR thru the Washers down that shaft to where ever...
So i took one by one bolt out and filled the hole with Heat-Resistant Engine RTV Silicone (i dont like it that much, but.. hm) . to prevent and other leaks it creamed the edges at manifold / heads too .. (see picture) ..
Next Day, i startet the car.. checked with my "CO Tester" adjusted IMS (Idle mix Screws) THEY WORK AGAIN! and Idle Speed screw down to 700 Rpm (no Vacuum Adv. Connected) and got my 3.5 to 4.0 CO adjustement on both sides..
I drove without Vac. Advance on 12Degree @ 800 RPM / 27 Degree @ 1600 RPM / 35.7 Deg. @ 2700RPM / 36 Deg. @ 3500 and 2x MSD Silver Light Springs (points distributor) and it was okay to drive... no pinging / knocking..
More timing test will come this week.
I`m soooo sorrry for taking all your time on something so simple, but i was so shure that this couldn`t be a Vacuum leak, cause after changing to the Edelbrock 2711 (350 Olds) Performer Manifold on May 21st this Year, i had a CO of 4 and the Mixture Screws have been adjustable.
Once again.. Big Big Big Thanks to all of you here at ClassicOldsmobile, your inputs & supports in this case have been over the Top!
July 12th, 2022, 06:45 PM
