Technical 1952 Chevrolet 235 Carb? issues

Stock in a 1952 Sedan. Runs rough. Seems to be on point for time. Reman carb, new gas tank, distributor newer. Again, all stock.

When you put your foot on it, it stutters or dies. Will idle, and it does run good once you get the revs up there, and it's going.

Can be rough to start, automatic choke.

New fuel pump.

Stock 6V system.

Thoughts?

 

Stuck heat riser flap at the bottom of the intake manifold, actually an integral part of the exhaust manifold.. Make sure that flap articulates and the spring is there and not broken. That's my guess based on the above info.

 

Check that it moves freely, with the spring intact. OK, that is something to check out. Basically just sticks in position and gives issues?

 

The spring is heat sensitive and heats the plenum on the bottom of your intake and then slowly moves to exit the exhaust. If you have a shop manual it neatly shows the operation, if you don't have one you need one. I've heard Tom Langdon, a retired (but highly active) GM engineer in the 6 cylinder division speak to the necessity of intake manifold heating.

 

In addition to what has been mentioned look at the base gasket on the carb. If the hole does not line up with the gasket slot the power valve will be in the 'rich' position all the time

 

Have you checked the accelerator pump shot?

 

Distributor turn when you open throttle ? Vacuum advance isn't working if it doesn't move. And the carb base doesn't use a gasket between the phenolic block & carb. Why not start over with a compression test & adjust the valves, then tune it ...

 

302GMC... hypothetically, if I have a gasket between the phenolic block and carb, what kind of issues can I anticipate?

Because I know there's one there right now.

Compression was good, worked to get the time as close as I could through the peep hole in the bellhousing and TDC. I have tried this sequence multiple times.

Distributor moves with the vacuum advance A-OK.

I also need to check the carb gasket and hole in the base of the carb line up.

Will check on these things, in addition to the manifold / spring /flap.

I hope one of you has just put me on the right track.

Also, I am going to put a new copper tube between my carb and intake manifold, and insulate it well, somehow. To ensure it gets a good draw of hot air to the auto choke, as appropriate.

 

all of this is very good advice but I will add some real world experience when I was a lad working in SERVICE STATION and these engines were in abundance check the carb body to base mting screws were notorious for coming loose causeing vac leak and creating symptoms just like you describe also check intake bolts and/or gaskets hope this helps

 

Will add to list, accelerator pump was squirting strong as well.

 

If the gasket aligns, no problem. They just didn't come with one when new. A gasket enables a good seal in lieu of removing the block & sanding it flat - no one working for a living wrenching would, anyway.

 

The whole gasket alignment scenario has me wondering, that will be one of the first things I gravitate to (hopefully this weekend).

 

So I have to admit that it's been a while since I have worked on this car. So far, manifold flapper is frozen solid and the intake gasket was blocking the carb hole.

Any tricks to freeing up that flap? Got a whole lot of penetrating oil on it right now, and will continue to work it in the usual hammer/pliers/PB Blaster method.

 

In fact, the spring is completely missing. Found another one of those, more PB.