Carb Tuning / Vacuum Problems?

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Actually, the rotor should point to the 1st intake bolt on the intake above cylinder #1, the green line on the pic. Yours is pointed at the red line. Did you have the oil pump/distributor drive gear out of it for any reason? If so, try pulling it out and rotating it 1 tooth. If not, it may have jumped timing.
 
there are 18 teeth on the drive gear, it could point at the wiper motor and wouldn't matter as long as the plug wires were rotated/clocked around to compensate.
 
New plug wires haven't helped. The connector on one ripped out of the socket when I pulled it off the #6 cylinder :banghead:. Set the timing to 16 initial, though, and did the idle mixture screws 1 and 1/2 turns out from all the way in as stated. So far no changes, still real flaky vacuum at idle. Compression test results to come.

Also did the hose thing, sounded like there might be a slight leak around the back of the carb. Wouldn't a leak like that affect things at all engine speeds though, not just sub-1000 rpm? The vacuum slowly drops from 15 at around 1500 rpm down to between 5 and 0 before the engine dies or idles really rough.
 
jimmyray said:
Did you double check the timing?
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It's set to 16 initial as best I could do with it wavering around so much at low idle, and I know the harmonic balancer hasn't slipped, so it's 16 unless the timing chain has slipped, which I don't know how to check without pulling the cover. It doesn't seem good, though, that the idle was jumping around like 5 degrees when the engine was lumbering around at 500 or 600 rpm. It was at 16 degrees advance at 900 rpm.
 
danielb927 said:
It's set to 16 initial as best I could do with it wavering around so much at low idle, and I know the harmonic balancer hasn't slipped, so it's 16 unless the timing chain has slipped, which I don't know how to check without pulling the cover. It doesn't seem good, though, that the idle was jumping around like 5 degrees when the engine was lumbering around at 500 or 600 rpm. It was at 16 degrees advance at 900 rpm.
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If your camera is handy, align the motor to TDC, take a pic with cap on, cap off, and rotor button off, so we can see the alignment of everything. It looks way advanced to me for where you have the rotor pointing, but it could just be visual acutiry on my part, or variations in alignment. Could be more.
 
Pics of my 66 cuda at 10 BTC, and my Duster at 18 BTC. My cuda cap is oriented similar to yours, but my Duster points closer to the #1 piston. Look at the orientation of my vacuum advance canister, as compared to yours.
 
Compression numbers:

Cylinder Trial 1 Trial 2 Trial 3

1 115 115 116
3 114 113 113
5 111 113 112
7 114 114 115


2 119 117 116
4 112 114 115
6 118 117 117
8 114 113 114

All of the cylinders were lower and went up on each compression stroke (example: 1st stroke 80, 2nd stroke 105, 3rd stroke 110, 4th 112, 5th 113)


Pic of the spark plugs (top=front of engine, left=driver's side plugs) look like 6 and 8 are the problem (wet fouling?):

p1020483e.jpg


2 of 8 brand new wires did this :banghead: :

p1020477p.jpg



Is it possible something's wrong with the distributor that cylinders 6 and 8 wouldn't be firing, or would be firing very weakly? The plug boots were tight, plugs were tight, definitely were in the right order... but that would make it sound lopey and uneven like it does I would think?
 
crossram383 said:
Could the EGR valve be stuck open ?
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Hadn't thought about that. Could be, could I tell by pulling it?

Here's a picture of it (or at least the side):

p1020470.jpg


It's exactly the way it was when I got it. EGR valve on there with the small vacuum line coming out of it cut short with a nail in it.
 
were all the plugs plulled out when cranking? I always do that to get a true reading and the carb ot WOT to pull as much air as one can.I think your problim is in thoes plugs.Most likly that egr is plug.
 
Snake said:
were all the plugs plulled out when cranking? I always do that to get a true reading and the carb ot WOT to pull as much air as one can.I think your problim is in thoes plugs.
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Plugs were out, throttle was wide open.
 
Take it off...if you can blow air thru it ...it's stuck open .

I have in the past just cut the shape of an EGR gasket out of a piece of sheetmetal and use that with high-temp permatex instead of the factory gasket to block off EGR flow definitively !

That way you can rule that out as a possible problem to erratic engine performance.
 
crossram383 said:
Take it off...if you can blow air thru it ...it's stuck open .

I have in the past just cut the shape of an EGR gasket out of a piece of sheetmetal and use that with high-temp permatex instead of the factory gasket to block off EGR flow definitively !

That way you can rule that out as a possible problem to erratic engine performance.
Click to expand...

I think I'll do that and make a plate, if I can find some sheet metal. It's pretty crusty and not doing anything anyways, so it can't hurt.
 
Another thing to check would be carbon tracking inside the distributor cap. Sometimes hard to see on black caps . Take a good look at terminals #6 and #8 .
 
Will do. I tried and can blow through the EGR valve when it's off the car and should be closed. I'm really kind of disappointed that these new plug wires just broke like they did though.
 
Danielb927 what's he status on this thread .....did ya' get the problems worked out ?
I also forgot to point out that one of the secondary venturis has carbon on it and the other looks clean ? (Maybe has something to do with EGR being stuck open )
 
Sorry for the lack of updates, been busy with school and I just started another thread, but want to move back over here. I blocked off the EGR (just used the stock gasket under a sheet metal cutout under the EGR valve) and gained some high-end power, but still have the idle problems. I realized the leak could be in the 5-way vacuum fitting in the manifold with 5 rubber hoses plugged by screws coming out of it. You'd think I would have thought of that before. Anyways, I'll plug that up with a bolt and some teflon tape and see how she runs. That plug is behind the carb barrel with all the carbon buildup on it, too, so hopefully evidence I'm in the right place. Should be able to give her a run this weekend and see.
 
And yes, there is some carbon on the contacts inside the distributor cap, although they seemed pretty much the same on every cylinder.
 
Have some new symptoms. I unplugged cylinders 6 and 8 and it ran pretty much exactly the same. Good news is, she's in good enough shape to idle on her own on 3 cylinders! I just kept unplugging and she kept running. The wiring on this car is pretty old, I'm not looking forward to going through it. Any ideas where to start?

When all 8 are hooked up, it will either run at around 1500 in park, or die. Sometimes I start it and it runs up around 1500, and I have to give it a real hard rev before it drops down and dies, otherwise it just goes back to 1500. Sometimes when I start it, it never stays at 1500.

With 6 cylinders hooked up to spark it was running about the same. With 4 cylinders on it idled at 1200, with 3 it idled (relatively smoothly) at 1000.
 
Time to dig up this old thread again. She's running better than before (thank FABO for that!) but still not great. Things I've done so far:

- Plugged the crossover holes in the manifold
- Checked a lot for vacuum leaks and can't find any
- Noticed some definite carbon tracking on the distributor cap and on the tip of the rotor
- Checked fuel pressure, steady at 7 psi, stays there after shut-off

I am leaning more towards ignition as the likely problem than carb issues. Problem's mainly the same as before. When the engine gets below 1000 rpm (down around 700), the vacuum goes back and forth between 0 and 5. It's up around 14 and fluctuates slightly when the engine's around 1000 rpm.

What's the next thing to look at? I'll try to start up and get another sound clip up soon if those help at all.
 
15-16 degrees at 6-700 rpm.

Also just discovered the tach has been connected to the + side of the coil, but still worked. I'll switch it over to the - and see if that changes anything.
 
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