Technical Idle issue

I have a 35 ford that I have been rebuilding and the fateful day came for her to start and she did. The problem is thaf it won't idle on its own. The car will only stay running unless i have the choke flap almost closed and the throttle reveved to 1500 to 2000 rpms tried 1" spacer plate and new seals but still having the same issue. I have a sbc 350 in it with a holley 650 spread bore the carb was also just fully rebuilt by a carb shop. If anyone has any insight or experience with this kind of issue it would be a huge help.

 

Tell us about the ignition timing

 

With the timing we have it set top dead center but we did also try setting the timing back to 10 before. Because we read a few break in guides and attacked to a couple shops and they recommended it. But that was for having the enginactually at an idle so we went back to top dead center and kept the distributor loose to adjust while it was running which it sounded like it's where it needs to be but idling is 1500 to 2000 rpms. The big thing is when we aren't controlling the carb the engine dies out

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Vacuum leaks??

 

Sounds like you might not have an idle circuit in the carb, or you have a large vacuum leak. You might want to talk to the carb guy that rebuilt it.

 

Is it a complete fresh engine, used engine with an intake/carb swap, was it running good then you changed something and now it won't idle, if so what did you change ?
Need a little more info but sounds like a vacuum leak, is it the right carb for that intake, spreadbore on spreadbore ?

 

It sounds like a vacuum leak to me. You don't have a large open vacuum port on the back of the carb that needs to be plugged do you?

 

How old is the carb? I never had much luck with the 6210, 20 some years ago...at the time, the carbs I was playing with were over 20 years old, and they just didn't age well.

I'd see about finding a good used Quadrajet to put on it, if you have a spread bore intake manifold If it's a square bore, and you have an adapter to mate the spread bore carb to it, then try an AFB or a square bore holley.

 

It is a fresh motor that hasn't been run before this was our first time starting it. the intake thats on it is the one that came with the motor or the one that's been on the engine since the late 70s.. It's the intake off of a 71 vette I checked and all the vacuum ports that aren't being used have plugs on them.

 

This is the intake I have and the carb. It is a 6210

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Do you have anything plugged into that large vacuum port on the back of the intake manifold?

 

Put your hands over the carb opening , slowly close off the opening , if the engine speeds up ??? Yep ! you got a vacuum leak somewhere ,!!

 

Do you have a vacuum brake booster? Did you run a hose to it? If you did you might remove the hose from the fitting on the booster and plug it to see if that is the source of the vacuum leak

 

It does sound like a vacuum leak. Make sure you have the correct gasket between the carb and intake, and also that the secondary butterflies are sealing their bores tightly.

Power brakes? Check the hose to the booster.

 

Get a new Carburetor. JMHO

 

They had a couple of difbase gaskets for the q jet and replacement holley . If you dont have the correct one itll give a small vacuum leak . It can only be identified by removing your carb and checking the seal on both the manifold and carb . Or the riser and the carb AND the manifold

 

This plus this equals this

 

Not if you know how to apply the Teflon tape...