307 Chevy running rough in the heat.

My room mate has a 307 Chevy in her 66 Chevy Caprice. Since it has gotten hot it has started "chugging" when she is driving it like it is about to die and she has to slam the gas when she goes from an idle to taking off at a stop sign or light to keep it from dying. The car has a lot of old rubber lines and my first thought was maybe they are expanding when it gets hot like brake lines do (it was 103 here yesterday) but I don't know if they work the same way.

It was also idling high when she got it but she just left if alone since it was running okay otherwise, After it started the "chugging" thing and the idle to takeoff thing I adjusted the carb down a little for her thinking that may be part of it but it is still doing it.....Anyone have any thoughts or suggestions?

Thanks

 

sounds like a Vacuum leak..check all those rubber lines..if they are old like you say..8$ worth of rubber tubing can save the day..they get dry and crack

 

also check the fuel filter, might have lots of junk in the tank, friend had similar problem in his case the "sock" filter in the tank was disintergrating and the filter in line looked like a million small ants were in there. good luck

 

That and maybe a carb rebuild is in it's future(accelerator pump taking a shit and leaking in air) The 307 is a good little motor, I like em

 

I figured it was something simple but I'd never come across anything doing exactly that so I wasn't sure. Thanks a lot guys. I'll check the filter for her and replace those lines and see what it does. I appreciate it.

 

When she floors it what does it do when she lets off?after you check or change the hoses you may want to change the accelerator pump athe very least.try pulling one hose at a time to see wich ones change the idle too.check each port to see if it is pulling vacuum as well.check the transmission modulator as well.it will cost more than 8 bux to change all the vac lines,try and isolate it down first.good luck and yes it is fn hot here!!!!!

 

points?
change the condenser.

 

Vapor lock/fuel boil?

 

That's what i'd try too

 

She says when it's hot after she floors it she still has to keep her foot on the gas to keep it going. Would that be accelerator pump? I'm changing the hoses and carb filter as soon as she gets home.

 

If the stuff you try doesn't work check where the fuel lines run. Make sure they're not near any heat source I.E. headers/exhaust manifolds. Also try a spacer under the carb. I had a 383 Mopar that needed the spacer or it would do exactly what you're describing.

 

If it did it when its cold i might lean towards the pump,but if it runs fine till it warms up,i would look more for vacuum leaks.then maybe electrical like the coil does it get really hot?they usually dont last long when a problem arrises.....