starts great cold, turns over alot when warm...please help!!

[Ramredneck]

I have a 1977 GMC K20, 305, 4 bbl. New starter, solenoid and carb. When it sits for a few days, i give it a pump or two - turn key and starts up great.

After its warm and shut it down for 20-60 minutes or so, it will crank crank crank crank (whether I pump it or not)...i get it to finally start at a low RPM (usually while fluttering the gas pedal).

What does this sound like, I don't really know where to pin point - please help.

[lurch115]

it sounds like vapor lock....what kind of carb. did you put on it?? might try an open element air cleaner.....or if you haven't done it lately....a tune-up works wonders...

[benoit454]

I had a simialr problem on my monte carlo, but it has an edelbrock carb and weiand alum. intake. I was having heat soak/perculation in the carb, a heat insulator fixed my problem.

Also had the same sorta thing happen on our old 86 k10 when it was stock. We plugged the fuel return line off because no matter what after taking a quick spin and shut off, it crank, crank, crank, we plugged the return at the pump and it fire up alot easier on a warm refire.

[Ramredneck]

It has a new Holley 650 carb, and no I didnt put it on. But before I changed the starter/solenoid - i didnt have this issue. I think I will do a tune up since I am not sure when it was last done, but looks decently new.

What is the heat insulator that you mentioned? Where do I get it/installation knowledge?

I do have an open air cleaner. Thanks for your help, let me know if there is anymore input...thanks!

[benoit454]

Well they used to have heat insulators for quadrajet/thermoqads, and mines from edelbrock. I looked up the number in my summit catalog, checked autozone and advanced for that number, and they had it. I went in pre-paid for it, next day it was there. Mine was only doing that in the summer time, like 80's and 90's, never had it out in the cold since it has no heater so I'm not sure on that. Someone said edelbrock carbs being aluminum bodies were bad for it. I don't know about the holley one.

As for install it's easy, take the four carb bolts loose that hold it on the intake, lift it up, put the insulator down, put carb on, reinstall bolts.

Or you can remove all the stuff from the carb like I do, the brake booster vacuum line, pcv line, throttle cable, kickdown cable, fuel line, vacuum advance line, any other lines and then set it out of the way once you get the four bolts off.

[Ramredneck]

Yeah I was completely wrong - I do have Edelbrock Carb. I understand what your saying - and will wrap my starter with a heat wrap and install the spacer that summit has. Thanks so much!

[benoit454]

Heat wrap might help but I doubt a spacer will.

If you get a spacer it needs to be a phenolic one. The aluminum ones would just transfer heat right into the carb like it does right now. The phenolic don't transfer heat so they work as a heat insulator. Same as the edelbrock heat insulator gasket. I think the heat insulator from edelbrock would even be cheaper to buy then the spacer. It was when I checked because I was going to use a spacer instead, but since they cost more I just bought the heat insulator gasket from edelbrock. Like I said summit and jegs have them and so does advanced auto and autozone, just gotta get the part no. for the heat insulator.