Hello That time of year again , almost 100 degrees My 1963 meteor 260 V8 gets heat Soak bad after shutoff for a few minutes, a few minutes of driving and it's back to normal . When it's heat soaking it idles very low, and stalls . What's a good fix for this , raising the idle in summer or should I fiddle with the mixture when it's doing it ?
I only heard of heat soak on turbo ricer cars. upgrade your intercooler for your turbo or reposition to get better airflow. Or if you mean the car just heats up to much under the hood then get some better ventilation. If its the engine overheating then check/flush or upgrade the cooling system. if the issue is at idle and not highway speeds then its your fans. if highway then your radiator. Or if you mean the fuel is evaporating then heat wrap the fuel line or coat it in lizardskin ceramic heat paint stuff. or even rerout the line away from the engine.
You got a carburetor?, you got problems. Modern FI "self tunes" based on throttle position, coolant temperature, air flow, and other inputs. A carb is tuned for the best of all possible situations, so as the weather changes, so does your tune. Long story short, a carb will work just fine, but you may need to tweak it from time to time.
I remember in Australia in the 1970s we raised the hood hinges about 2 inch so the rear of the hood had an escape route for the hot air.
I believe he may mean vapor lock. Try the usual things, add a non-metallic carb spacer, route fuel lines away from heat, you can wrap those too. Make sure the fuel bowls aren't leaking gas into the manifold when you shut it off.
If you have an electric fan, you can byp*** the ignition switch and install a thermo-switch so it turns on and off with the temp of the radiator. That doesn't really do a lot for the engine per se, but it does keep the coolant cool, which should help with your issue. If you have a mechanical fan? No such luck; though you could install a pusher fan in the same configuration if you wanted.
My vote is the fuel, modern gasoline is formulated for injection. Vapor lock and/or idle mixture goes out the window too once it starts boiling in the carb. One thing you can try is Marvel's in the fuel tank. Old timers used to add about a pint of kerosene or diesel per tank.
Sounds like heat soak to me. http://www.thecarburetorshop.com/Troubleshooting.htm#Fuelleak Probably a fuel problem (too volatile). A phenolic spacer under the carb may help. It may also require a somewhat higher curb idle all of the time. Insulating the fuel lines may help. Probably best solution is run the engine at a fast idle for 30 seconds or so to normalize the system, and wait for cooler weather. Jon
Heat Soak, yes! Shutting the motor off after running at operating temperature causes "heat soak". Ethanol in the modern gasoline boils at about160* and "floods" the engine while sitting at high temps. Some call it percolating, some call it heat soak, some call it vapor lock, however vapor lock usually refers to percolation while running and the engine goes rich and stalls, making restarts difficult. Sort of makes the theory of the elusive vapor carb not so much a "theory" if you know what I mean. As said previously, a phenolic carb spacer helps keep the temp in the carb in a tolerable range for easier restarts. Non-ethanol fuel (if you can find it and afford it) helps the situation. Adding a little Marvels, or diesel, or fuel oil helps raise the boiling point too. Adding a little xylene, toluene or benzene (components in different aviation and racing fuels) also helps by raising the boiling point, and are great octane boosters too. https://en.wikipedia.org/wiki/Xylene
How does the fuel vaporizing cause it to "flood", or "go rich"? I think you've got that wrong, it should cause fuel starvation not an overly rich condition. Flooding is a completely different situation, too much fuel.
Lifetime Midwest resident here. "Heat Soak" is when the vehicle temp goes up a little after it's been shut down, and while mainly a temporary situation it's definitely real. If you have a direct to water temp gauge you can see it easily. Ran at 180 the whole time, shut it down, watch the gauge go up to nearly 200. Worse in hot/humid temps, seldom if ever ever in the cold.
I solve this problem by slowing down my life... what's the rush? Sit back, have a gl*** of sweet tea, shoot the breeze and wait for it to cool off.... I always viewed "hot rodding" as a marathon, not a sprint.... when I am in the rod I have all the time in the world..... But that's just me... YMMV I now return you to actual solutions that may solve your problem.... Chappy
Gasoline vapors are heavier than air and go down into the manifold on a carbureted engine, where they collect after percolation. Upon restart during a heat soak situation, it is a rich condition evident by the black smoke that pours out the tail pipe. That's why you have to open the throttle fully to try and match the amount of air to the fuel already vaporized in the manifold. Carburetors are designed to meter liquid fuel and match it with a given amount of air. You don't get this condition with an EFI, because the liquid fuel is dispensed at high pressure nearer the point of combustion where they are vaporized. In a normal liquid fuel situation, only about 25% of the liquid is ever vaporized and burned even in an EFI situation. That's why liquid gasoline powered engines are very inefficient. In a super heated situation (up to the point of auto ignition), almost all of the fuel is vaporized, making it highly efficient and overly rich compared to liquid fuel. Believe it or not, there are some compounds added that are are never vaporized and go out the tailpipe as liquid droplets. Gasoline is made up of at least 7 basic compounds (8 if you include ethanol). They all boil or vaporize at different temperatures starting at about 100*. The reason being, gasoline burns like a camp fire. You start with a match to light the paper, then cardboard, then twigs, then sticks and finally logs. They are as follows: Pentane - 100* Hexane - 150* Heprane - 200* Octane - 250* Nonane - 300* Decane - 350* Undecane - 400* In a heat soak situation, all the light ends vaporize first and leave the heavies behind, making a mini-distilling condition, causing the rich condition in the manifold, making it hard to restart. There are also other additives like detergents and such, which complicate the situation, but for sake of this discussion not mentioned.
We had heat soak before FI and ethanol. We also had vaporlock which was sometimes a result of heat soak.
The HAMB is part of my lifetime learning endeavor. This has been one of those threads. Thanks, you guys.
You are right Phil. I learned a new term today. How about that! All this time I thought heat soak was sitting in a hot tub with a gl*** of wine.
Ha, I always thought that heat soak was what happened to my big block Chevy starters on hot summer days? Tried heat shields and everything I knew to keep it cool. Learn something new everyday!
lol... i wouldn't put my hot rod on I-5 in rush hour ...and i certainly wouldn't shut it off in rush hour traffic either. hell...i won't even drive it in a parade...lol Chappy
Yes, that is heat soak too. Not to steal the thread, but did you do the remote fender/firewall solenoid like Fords do from the factory? I always thought the heat shields kept the heat in, not out! Chevy starter solenoids don't like heat soak.
Quick one here... found a windshield squirter and mount it to the frame. Water soak gets rid of heat soak really fast! Not the right fix by any means but it was a fun and cheap fix. Worked just fine in the summer while running around the So Cal desert.
To answer the original question, I found on one car lowering the float level slightly helped the heat soak/hot start problems. On another I ended up adding an electric fuel pump. Modern fuels and vintage carburetion don't like each other. GM used a fuel filter that had a separate vapor line back to the tank to help with the issues of hot fuel and or heat soak.
Having a starter that didn't wan to turn when it was hot was what I always thought "heat soak" was. Agreed the Ford Solenoid trick and heavier battery cables helps immensely along with the heat shield and my 77 1 ton 454 is proof of that. Carb percolating or vapor locking in the heat is something that I have had experience with on my 48 before I had the hood louvered but I was towing a 16 ft U haul through Utah in the middle of summer with the 48 with a 283, Muncie M21 and the wrong gears and had to stop on one grade and dump ice water out of the cooler on the fuel pump and intake about five times to make it over the grade. On that little six I'd say it is just flat too hot under the hood. I'd go with the insulated spacer and maybe even fab a heat shield to deflect some of the manifold heat away from the carb and fuel line.
I always thought it was called "boil over". I have lived in the mid west, the south, the north and the west and never heard of "heat soak" and I never ever heard anyone use the term. Hmm...
I experienced heat soak on my OT daily driver rice burner. There were lots of TSB's and workarounds but the most effective was to just let the electric fan run for awhile and cool down the engine compartment then restart the thing. Only happened when shutting down after driving on hot days.
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