Heat Soak or what?
Thread Starter
Racer
Joined: Oct 2010
Posts: 474
Likes: 0
From: Bishop CA
Heat Soak or what?
I have a 75 sb. Last summer I was having some issues with restart after running on hot days. I called edelbrock since I have a performer intake and a thunder series carb. They said heat soak and sent me a wooden plate to put between carb and intake. Worked like a charm, but now 10 months later and the temp is 100 today. I drive it for 20 minutes shut it off and restart about 40 minutes later and it blubbers and hesitates. After a few minutes it cleans out and runs fine. Any suggestions? Thanks in advance.
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
Was going to suggest the carb isolator plate, but sounds like you've already got that covered. Good idea hosing in cold outside intake air if you're not already doing that. If the carbs jetted on the lean side, could also be part of the problem.
Thread Starter
Racer
Joined: Oct 2010
Posts: 474
Likes: 0
From: Bishop CA
Thread Starter
Racer
Joined: Oct 2010
Posts: 474
Likes: 0
From: Bishop CA
I just installed a new braided full line from pump to carb and even put a heat wrap around it. It is a little short tho and rests against the block. Think i'll put a small extension on it.
Melting Slicks
Joined: Feb 2006
Posts: 3,428
Likes: 5
From: Japan
If you're going to continue running it in hellish weather like that the only real solution might be running an electric pump...sounds like it's getting so hot in there that the stock mechanical pump isn't overcoming the boiling fuel at initial startup and the carb insulator is only working up to a point. Having braided line might not be the best thing either as the steel braid could be holding some heat...if it is laying on the engine it should be clamped out of the way with a rubber insulated (We call them 'Adel' clamps in aviation) clamp. And PLEASE don't put one of those glass filters under the hood (or anywhere else for that matter)...not only are they super-cheesy but they are a colossal fire hazard on a Corvette.
Race Director
Joined: Jan 2007
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Likes: 696
From: Danville Illinois
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I also have 75 sb that does this. Went to different manifold and newer holly. Still does it. After i shut it off, 10-15 min you can start to smell the gas, and will be hard to start (but will start) will clean out after 30 seconds.
Install a clear fuel filter like Timsride suggested for testing only. I set up my video camera and taped it. You can see the bubbles start small and then get bigger. Remember to take out the clear filter when done testing. Like birdsmith says, its cheesy and dangerous
I think the gas is boiling (vapor lock) in the gas lines, not the float bowls as i thought. As the gas boils the pressure becomes greater than the float pressure and lets it past the float seat and down into the manifold.
The engine temp is 190, i have two temps sources, factory gauge and an aftermarket mechanical gauge, they both say 190. I don't think that's to hot to do that. It has to be the gas line from the pump to the carb.
I am open minded to corrections on my theory and will take suggestions on how to correct this , hell its only been doing it for 33 years now what have i got to lose.
Any of this make sense?
Install a clear fuel filter like Timsride suggested for testing only. I set up my video camera and taped it. You can see the bubbles start small and then get bigger. Remember to take out the clear filter when done testing. Like birdsmith says, its cheesy and dangerous
I think the gas is boiling (vapor lock) in the gas lines, not the float bowls as i thought. As the gas boils the pressure becomes greater than the float pressure and lets it past the float seat and down into the manifold.
The engine temp is 190, i have two temps sources, factory gauge and an aftermarket mechanical gauge, they both say 190. I don't think that's to hot to do that. It has to be the gas line from the pump to the carb.
I am open minded to corrections on my theory and will take suggestions on how to correct this , hell its only been doing it for 33 years now what have i got to lose.
Any of this make sense?
Last edited by Mod75; Jul 8, 2011 at 08:40 PM.
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Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
Not sure an electric pumps gonna help, but do like using them on rarely driven carburated cars. Found the full Mallory 140 set up with bypass regulator and orficed return line work's well. Run the pump a bit before start up, then shut off to stall out on empty carb bowls to avoid fuel percolation.
