1962 394

Starts great, idles great accelerates good cruising.
Problem is if I keep it in say 1st gear and wind it out a bit, not high rpms but steady I'd guess 3500 to 4000 it misses, will fall on its face then pick back up, repeat.
If I give it more throttle it will clear up for the most part.
Sometimes it will take a few seconds to clear up but then it runs good.
I can make it do this in 1st or 2nd gear.

Fuel pumps rebuilt. New coil, plugs, wires points.

Any ideas? Carb issue? I've adjusted in sequence everything except the trans linkage settings per the manual.
Thanks

 

You might disconnect your vacuum advance and see if it clears up. What happens is people max out their mechanical timing and with high vacuum high rpm situations the timing is way over advanced due to what the vacuum cannister is set at.

 

I will give it a shot.
My initial timing is set to factory spec in the manual.

 

I had that happen with my car... I made a small bushing to limit the amount of vac. advance & it was fine.

 

Chiming in from CA, gasoline ain’t what it used to be.

In our state the best we can get is 91 octane with alcohol as a part of it, unless we go to a race track or airfield. Then we gotta pay. $$ I hope NC is better.

If you’re having trouble with a part throttle or full throttle knock/ping, have a look at Lars Grimrud’s article on vacuum advances and see if you have find an advance that advances slower than your Olds vacuum pot. I tested several and found a big Buick vacuum advance worked best in my 455’s.

BTW. Have and really like Parchment interior. Very clean.


Chris

 

I the timing and electrical check out. You didn't say what carb you had. Maybe jet up 1 or 2 sizes, increase float height, check rubber fuel line connections for cracks, fuel pump pressure. The pump should put out a certain amount of fuel while cranking, check the manual for specs.

 

No pinging or knock. It did ping a little when I bought it but I set the timing to spec and it stopped.
The issue is, to me, it seems it's running out of fuel. It starts to sputter then falls on it face then pucks up a little only to fall on its face again. It will continue to do that until I let off or give it more throttle.

I will try to take video

 

Rochester 4GC

Fuel pump has been rebuilt. Lines replaced. Metal line flushed. Tank, which was surprisingly like new inside, flushed and pickup cleaned. Have not measured flow but it puts out a good amount of fuel.

I read about upping jets on Charlie's carb rebuild thread. I'm curious about the floats also. That's what got this thread started. I'm considering rebuilding the carb so I wanted to eliminate all other possibilities so if I do rebuild it and make proper adjustments hopefully that will solve the issue.

Thanks

 

I noticed the screw holding the tag on the carb wasn't very tight. I took it off to read it.
So I went around the top of the carb and all the screws needed a little snug. I didn't gorilla fist them, just enough I could feel them seat tight.
The inlet fitting was also a little loose. Not dripping but a little seepage and I got a good crank on it before it snugged back tight.
Ran it with vac advance disconnected and it did not fall on its face but had a steady miss where it used to fall on its face.
Hooked vac advance up and it does not fall on its face and actually ran pretty good other than a small sputter in 1st when rpms start to get up there.

 

Have you checked the condition of your points and your dwell? Note any dwell changes will require you to reset timing.

 

yes. Dwell is at 30 and points are fairly new and clean.

 

Do you know what the total timing is and at what rpm it stops advancing? In other words, connect a timing light and rev the engine until the timing stops advancing and note the amount and at what rpm.

 

I will check this. Thanks

 

Dwell is at 29

Vac adv. connected
Initial timing is 30* at 890 RPM
37* at approx 1200 to1400 RPM
Timing is at 43* max at around 2200 RPM.

Vac adv. Disconnected
4* at 650 RPM
11* at 1100 RPM
21* at 2200 RPM

Specs are,
mech adv
9 to 11* at 1200
12 to 14* at 2000

vac adv
11.5 to 13.5* at 18"

I did not check vacuum.

 

I don't think it stops advancing at 2200. Did you run the rpms up to around 4000

 

I think the max I went was about 3600 with no change from 43*

I will run it again when I have help and can pay more attention to the rpms

 

I had similar issues on my 394 and thinking it was the original 4-Jet put a Holley on issue went away. Then Holley leaked so put a fully reconditioned 4-Jet on, issue came back. So my issue was the carburettor. Turns out my middle things on the intake manifold were getting super hot causing fuel to evaporate in the carb somewhere. I removed the intake manifold and put covers in there to block off the heat. The car is fine now, not an issue since.

 

I don't quite understand what you mean by middle things.

I have ordered a carb kit since it is seeping out of the gasket

 

He's talking about the exhaust crossover.

 

Too much heat coming into my manifold. I blocked that off now all good.

 

I was following your thread since you 1st posted & I was suspicious regarding carb gasket(s). A soaked base gasket in particular one which is dripping/seeping gas will allow air to enter the carburetor often yielding to a lean burn condition. Over time a gasket will accumulate some gasoline at which time it's time to change the gasket(s). The gasket(s) are designed to maintain a clean A/F mixture when they are dry & properly secured. Good you ordered a rebuild kit. When you have the carb removed, using a straight edge check the plane of the carb base for level straight, front to back, side to side and criss-crossed diagonally. You may find you only needed new gasket(s). Good Luck.

 

Gotcha
Is that a good idea?

 

Thanks
I'm hoping a rebuild and new gaskets will clear it up.
since I tightend everything up it is running better. Still has a bit of a miss though at part throttle.
The gas leaking is a definite no no so its getting rebuilt anyway