Hot start

[vectorit]

I've been noticing a problem with my burb, and it is starting to bug me with what could be causing it...

Drive for an hour or so, park and turn off the engine.
Come back a few minutes later, go to try and start and it just turns like the coil wire has fallen off. Starter is turning the engine just as normally as if it was any other time to start.

Wait five or ten minutes, and she fires right up.

This doesn't happen all the time, but when it does it happens of course at the wrong time. (In a hurry).

The under hood inventory...
327
Quadrajet
Original rams
Original cast iron intake
strong battery
strong starter
Manual trans
Pertronix ignition, this problem was present when I had the points ignition.
Plugs are AC R45TS, gapped at 40.
Timing is spot on.

The only piece of hardware that is possibly a weak link in this, is the plug wires since they are old but not damaged. I've just put off on getting new ones, just wondering if they may be getting in the way of starting on hot days.

What I have noticed when she does eventually fire, is it seems like it is flooded. Since when she does fire up, I notice some black exhaust. Though I don't smell fuel. I typically don't even press the go pedal prior to starting when the engine is already warm, but when this happens I have to press the pedal down a little it seems.

EDIT: added the type of intake manifold

Any thoughts?

[shoei1993]

well for my 64 c10 i have a 350 in and when its hot i have to hold it to the floor. so try holding it to the floor

[mighty_mike015]

In my experience that could be caused by heat soaking the carb. causing the fuel to vaporized before being introduced in to the combustion chamber. BUT your list doesn't mention an aluminum intake to dissipate the heat into the carb. So this may not be your issue but I will share anyway. We solved this problem on my buddy's (aluminum carb and intake) with a non thermal conductive carb spacer. Fixed the problem we were having. Might be something to look into.

Mike

[Piece of Work]

I just went through this on mine. I bought a 1" phenolic carb spacer on e-bay. Installed it and problem solved.

[El Jay]

I'd guess the carburetor is getting hot and the gas is percolating, dumping raw fuel into the manifold.

[68gmsee]

If you see black smoke after it sits for any length of time, it's flooding. You may have to check the carb for leaks.

As mentioned above, hold the gas pedal down while cranking to see if it helps.

http://www.carcraft.com/howto/57178/index.html

[Shyguy]

I have similar problems and I think the carb is leaking, but so far have not got to check it out.

Also if I let mine sets over-night it will not start until I spray some starting fluid in the carb.

I have heard that Q-jets are prone to leaks, but don't know for sure.

[leddzepp]

Originally Posted by mighty_mike015

In my experience that could be caused by heat soaking the carb. causing the fuel to vaporized before being introduced in to the combustion chamber. BUT your list doesn't mention an aluminum intake to dissipate the heat into the carb. So this may not be your issue but I will share anyway. We solved this problem on my buddy's (aluminum carb and intake) with a non thermal conductive carb spacer. Fixed the problem we were having. Might be something to look into.

Mike

x 2.

[68gmsee]

Originally Posted by Shyguy

........Also if I let mine sets over-night it will not start until I spray some starting fluid in the carb.

I have heard that Q-jets are prone to leaks, but don't know for sure.

Yes, some Qjets are prone to leaking. The link on my post above shows where they leak and what to do about it.

Here's a pic.

[vectorit]

Originally Posted by mighty_mike015

In my experience that could be caused by heat soaking the carb. causing the fuel to vaporized before being introduced in to the combustion chamber. BUT your list doesn't mention an aluminum intake to dissipate the heat into the carb. So this may not be your issue but I will share anyway. We solved this problem on my buddy's (aluminum carb and intake) with a non thermal conductive carb spacer. Fixed the problem we were having. Might be something to look into.

Mike

This sounds like the most logical cause to my issue.

Though I am perplexed, thus I can't pop the Champagne just yet.

Being that I have been with this Suburban for as long as I can remember, I have never heard my Father complain about such a problem nor have I ever experienced it before myself.

Other than the Pertronix, this engine bay is as it has been for most of it's life.

I plan to check out my choke set up right now, since it has stopped working correctly. It's the thermostatic spring type, and it just doesn't seem to bring the idle up anymore when it's cold. I am wondering if this maybe getting in the way from time to time?