quadrajet hard start

[Cornfield creations]

I have rebuilt my quadrajet about 3 years ago and it has always done this and I have just been blowing it off.

When cold it starts just fine, I don't even need to pump the gas. It can sit for 3 days, go in and hit the key, starts right up. But when I drive it and the engine gets hot and it sits for more than 30 sec. it acts like its flooded. Then it sputters and I have to clean it out. I feel like I am wasting a lot of gas doing this.

My only thought is maybe percolation in the bowl when it gets hot.

It's my original quad, rebuilt to a stage 2 spec. Sitting on a GMPP vortec aluminum high rise intake made for the quadrajet. Sitting up higher I wouldn't think heat would be an issue, but anymore I don't rule out the simple stuff.

What do you guys think?

 

[sledheadak]

did u put the insulator gasket under it? they also make a heat sheild that goes under them

 

[Cornfield creations]

Yeah, it's the original style super thick gasket. I guess I could try a carb spacer and see if it helps. This engine runs at 195-210.

 

[TerryD]

It's rare for the later model carbs to do this, but the little plugs in the bottom of the bowl where the fuel turns under the jets and heads back up to the boosters is known as a bad leaking spot of Q-Jets.

Also, after a warm shut off, get out and take the air cleaner off. Look down through the carb with a flash light and see if the throttle plates are wet. That'd be a sign that the fuel could be boiling out of the bowl or possibly the needle not holding back some latent pressure in the lines.

 

[1-ton]

It's rare for the later model carbs to do this, but the little plugs in the bottom of the bowl where the fuel turns under the jets and heads back up to the boosters is known as a bad leaking spot of Q-Jets.

X2 on that. Leaking plugs in the bottom of the throttle plate was a common problem with the quadrajet.

 

[Cornfield creations]

hmm, may have to check them. They didn't look to be leaking when I rebuilt it, but that's not to say they weren't leaking. What type of epoxy do you use to seal them?