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Re: Overheating 57 dual quads
Stuart...any idea where to get the spacers?Comment
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Re: Overheating 57 dual quads
Ted,
I would do what others have mentioned. John H said that the intake manifold does have an exhaust heat crossover so i would definitely eliminate that.
As Stu mentioned, carburetor insulating spacers are probably available in 1/2" thickness so I would see if there is enough hood clearance for this. I wouldn't use the stacked multiple aluminum plates and gaskets that are sold by Mr Gasket unless absolutely necessary. If you do, be very careful when torquing the carburetor base nuts as the stack of gaskets/plates will crush the stack on the outer corners and distort or crack the base of the carburetor.
These heat soak fuel boil issues are new with the new 10% E10 fuel. You're definitely not the only one having these issues. It wasn't near as bad when the max amount was at 5% but when it was increased to 10% a few years ago, serious fuel boil off became very common.Comment
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Re: Overheating 57 dual quads
Just a word about re-starting an engine with a heat soak condition; Many of us were taught that if the engine didn't re-start right away to give it a little more gas, and if that caused it to flood, push the gas pedal to the floor and crank until it cleared out and fired. The correct or better way to re-start is to crank the engine for 3 or 4 seconds with your foot OFF the gas, then apply just a small amount of gas pedal until the engine fires. This allows the engine to expel the already present over rich mixture and clear the cylinders for a fresh proper mixture.
I only learned this about a year ago (I'm 74) and felt stupid to finally have learned how to start under heat soak conditions. I go out to buy a paper and retrive the flyers from Walgreens and CVS every Sunday morning so make a couple of hot soak re-starts. My trips are much more enjoyable now when I can get my Vette to start right away with the usual onlookers in the parking lots. I no longer have to leave them in a cloud of black smoke.
P.S. I've cured my carb's "post nasel drip", but either you won't or can't do all the things I did to accomplish that (one being to find a source of non-ethanol gas - thanks to the help of my friend Michael H.).
Stu FoxComment
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Re: Overheating 57 dual quads
Ted, that was my problem, the heat soaking in the carbs. I also ran about 14 degrees. I used to autocross the '57 and experienced the problem a lot along with my sprints on US-6 and I-69. The small blockoff for the crossover worked.
SteveComment
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Re: Overheating 57 dual quads
Just to add to this post the boil off conditions in the float bowl contributes to rich running conditions. The vapor gets sucked into the air cleaner and changes the A/F ratio depending on the temperature of the fuel bowl.Comment
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Re: Overheating 57 dual quads
Tim --Thanks for that thought. That probably explains why it does a bucking Jerking routine till the mixture gets cleared out. I am going to be running on a chassis dyno and measure mixture while measuring and tuning. I think mine has always run rich. Finding jets is a problem but until I know where it is I don't know what to try. I am thinking of getting one of the A/F mixture meters that uses an O2 sensor to measure.Comment
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