I have just put a HO 350 in my 86 firebird which used to have a 305. It has an edelbrock intake and carb and edelbrock headers with 3" cat back exhaust. Engine runs great on the highway and when it is cool, however on hot days in the city it will idle from at lights and bog out on take off. I have eliminated a spark issue with new plugs, wire, distributor and a new MSD box. I feel that the heat under the hood is evaporating the fuel either in the carb fuel bowls or in the fuel line that runs above the intake. I am thinking of tracking down a turbo hood with a vent, or a cowl to alow some heat to vent off, just wondering if anyone else has any ideas or have had the same problem.

Thanks

 

You could try an insulating spacer under the carb to insulate it from the heat of the manifold.

 

Does the fuel pump have a return line??

Auggie

 

No, fuel pump doesn't have a return line.

 

He would still have to get a cowl hood in order to run a spacer. especiaqlly if it is a 1" spacer. You will run into hitting the hood and not having enough room for an air cleaner without that extra room from a cowl

 

ive been having a simular problem as well ... in fact im going to add a spacer today to see if it will help ... ill let you know what happens ... tao

 

At the risk of raising the ire of those smarter than I, the Carter M6626 is a 120 GPM mechanical pump with return line. In 100 degree heat with engine temps over 200, no vapor lock or stumbling problems.

 

Well there you go. Five7's mech. fuel pump has a return line back to the tank and no problems.

Auggie

 

I also have an air cleaner with snorkel inlets beyond the hot underhood air.

 

And, I should say, factory V6 fuel line routing with the lines routed in front of the crossmember to get them over to the fuel pump. Together, these probably reduce fuel heating issues.

 

My car had this exact same problem. Mw66nova told me it was prob vapor lock so I put a stock pump back on it and it solved the problem.