Well I thought my troubles were solved with the vapor lock issue. I re-routed my fuel line away from the block. I used hose and a clear fuel filter. Drove like a new car, about 20 minutes. Then stall. I looked at the clear filter and gas was boiling. You could here it in the fuel pump. Carlton Racing make insulator that replaces the steel mounting plate. Has anybody used one? I have a 64 Bel air wagon and don't want to take tank out and run a return fuel line setup if I don't need to. Sent from my SM-J727R4 using The H.A.M.B. mobile app
If the fuel pump can't pull from the tank, the symptoms are just like vapor lock. Have you checked the lines from tank to pump, hoses, pickup, pickup sock, gas tank vent, vented cap etc.? Check the line from the pump to the carb as well. If it's blocked/plugged, same symptom.
There is a fuel filter that has a fitting for a return line WIX Filters - 33040 Fuel (Complete In-Line) Filter, Pack of 1
If it were me I would return the fuel line back to stock. All steel 5/16” line up to the glass filter infront of the carb. No rubber. It didn’t vapor lock then and should not now. I did it on my engine and even tho it’s not a SBC it’s fuel pump is low and in front. I have chosen to put 1oz of Sta-Bil Marine with every tank to help with the ethanol in our fuel. I have checked the temp of the steel lines and found it in the 120* idleing in the garage. I fell it’s too high but have not had any vapor lock. I have a 180 thermostat, a tight fan shroud, and a 5 blade fan. If you don’t have at least a 3/8” pheonalic insulator under the carb you need one. Also what intake and carb are you using? Good luck.
There's been a bazillion SBC with stock fuel pumps that didn't vapor lock. Find what's different about yours .
But they didn't make gas the same way back then....modern gasoline seems to be more volatile. I won't argue with your suggestion, though
You need to insulate the fuel lines, back to front. Somewhere your exhaust is super-heating the fuel line, and under hood.
This has Bern talked about on many threads before. The problem is the modern fuel, it is different from the 70's. The common recommendation for carburetor vehicles is to put an electric pump near the tank. Turn it on when the engine weezes. Problem solved. Also, I'd suggest getting rid of the glass fuel filter before the glass breaks and causes a fire. Phil
Well if convinced it's actually boiling, then an inexpensive digital thermo will show you where the issue is.
Is it truly ‘boiling’ due to heat, or is the line pressure being reduced and making it ‘boil’ at a lower temperature than normal?
Yep than I’d bring it back to original. The fuel line is right at the front of the carb and cooled by the fan. I’d make sure you used the factory bent radiator hose too. I’m not sure on this but if the manifold has a passage up to the carb base from the right to the left, most or all of it it in the carb base around the front.. clean it all out. The holes in the manifold can be done with drill about 3/8” as I remember, then wire open the flapper at the end of the exhaust manifold. This will take heat away. Those are great carbs pre Q-Jet.
Is the car stock height or has it been lowered? This will reduce air flow under the car or worse trap hot air under the car depending how low it is. Verify the engine is correctly tuned, slightly rich will cause fuel to continue to burn in the exhaust which will cause higher under car temps as well. A high flow fuel pump can cause vapor lock by causing too much of a pressure drop. Too many bends(90° fittings) can cause a pressure drop. Too long(and not larger enough diameter) of a fuel line can also cause a pressure drop. Combined with a little extra heat the problem compounds and you get vapor lock. Verify any fuel hose you are using is compatible with newer fuels. If you are using some new old stock the hose may not work well with ethanol tainted fuels.
No exhaust leaks that might be putting hot air on the fuel line? I had that problem with an ot truck that always ran great before. Killed my vacation and cost me a spendy tow home in the process. New exhaust that got installed closer to a fuel line than it was before? You didn't happen to change gas caps lately? Non vented caps will let you run until the fuel pump creates a vacuum in the tank that it can't overcome and stalls the engine and acts like it is out of fuel even if the tank is full. The fuller the tank the quicker it stalls. I could get about 4 miles with my 51 Merc if it had around a 1/4 tank or less before it quit. It took three Stant vented caps before I got one that was actually vented.
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