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SB,
Not sure how to delicately phrase this, but return lines for a carb fuel system don't do squat. The only return line that might help would take the fuel directly from the float bowl - not sure how this could be done but I'm willing to listen. How do I know? Been there, done that. More than once. Return lines keep the fuel that's in the gas line circulating so it doesn't get warmer by returning it to the tank, typically from a regulator, not from the float bowl. It's the overheated gasoline (haha) in the toasty warm float bowl that causes the problems. An insulator/heat deflector may help some, but if the car sits, not running, well, good luck with that. Running the fans may help some, but how long does it take to cool the underhood area after the car is stopped? Tough problem. No easy, simple solution. Sorry, Tom |
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I'm going with my original plan of 1/2" phenolic spacer (with sealing gaskets on both sides of the spacer). The reduction of conductive heat transfer from an aluminum intake manifold into an aluminum bodied carburetor should be quite substantial given that right now, all I have that separates the two is a paper thin gasket. I gotta start somewhere and being an aerospace thermal engineer by occupation, I've gotta believe that cutting down the conductive heat transfer from manifold to carb by using a low conductivity phenolic will provide some gains. Stay tuned. |
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You should add a heat shield also. I like the 100 octane low lead - it’s expensive but you will enjoy the ride. Afaik it’s ok to mix the different grades. There is also a 114 or so octane that you’re not supposed to pump directly into your car - 5 gallons of that in a 15-20 gallon tank would work. I believe the higher grade fuels are actually better than the everyday gas for engine, gaskets , etc.
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non-oxygenated race gas. It is PURE gasoline made without ethanol. Blending race gas with pump gas is no problem. You will need to do a little math to get the desired octane rating. Example is a 50/50 blend of 91 octane unleaded non-oxy pump gas with Sunoco 260GTX 98 octane unleaded non-oxy produces a blended octane rating of 94.5. I run the above mix during hot Summer months or car parades. BBF, carb, mechanical pump, no return line or phenolic spacer. Fuel line is 1/2" SS braided Aeroquip with air-gap between block. +90F car parades with lots of stop-n-go but no vapor lock. Hot restarts have not been an issue during parades as well. May not work for everyone but this seems to work on my car. Really hope this helps you out even a little. Read Sunoco's info about mixing here: https://www.sunocoracefuels.com/tech...ulating-octane Bonus: burning race gas your exhaust will smell a bit sweeter!! |
Installed a 1/4" spacer with gaskets top and bottom. Has made a dramatic improvement with hot starts. Ditched the oval Cobra air cleaner for a 14" Sprectre air cleaner with a the blue synthetic media around the perimeter AND on the top cover. Looks really good, not to mention much more air flow now. Matches nicely with the blue plug wires.
Tried to upload a photo but the file won't upload, even though the file size is below the 99kb max limit for jpeg files. Have had this recurring issue now for months. Not sure what is going on but it is very frustrating. :mad: |
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