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Do you have the correct 1/4" spacer gasket installed? What is your timing set at? Heat riser system still on the car? Crossover blocked?
Jebby
Hello Jebby and thank you for responding to my conundrum.
My timing is set at 36* at about 2,500 RPM, and the exhaust heat riser was removed when I installed true-duals. At the risk of sounding obtuse, what crossover are you referring to? There is no exhaust crossover, if that's what you're thinking about.
And yes, the 1/4" thick gasket is installed between the manifold and carburetor.
From: At my Bar drinking and wrenching in Lafayette Colorado
Originally Posted by JCurtiss
I ran the car for about 12-15 miles at mixed speeds, disconnected the fuel line from the carburetor and let it heat-soak for 10 minutes. I reconnected the fuel line and started the car and did not experience a hard-start problem. So what does that mean? So what else could the problem be? Jason
Your test results are indicative of a fuel control problem with the carb. This is not uncommon. Possible causes are:
.
Small piece of crap in the needle/seat
Defective needle/seat
Defective float
Wrong float installed (i.e., brass float or wrong year float for bowl)
Float needle clip installed wrong
Leaking seat gasket
Crack in float bowl
Excessive fuel pressure
If it were my carb, I would do a bowl pressure test to see if the problem can be duplicated and identified on the bench. I do these tests any time I have the hot-start complaint on a carb, and any time I do a fuel fitting inlet thread repair on the bowl. Here are some photos of my test setup when doing an inlet thread repair pressure test:
The seat, needle and float are installed and the float hinge pin is held in place with a flat bar and a c-clamp:
When doing an inlet fitting repair leak test, the test is done "dry" with no liquid in the float bowl. The float is held in the "up" position with a light spring under the float to close the needle/seat, allowing pressure to be seen at the inlet fitting. Inlet fitting testing is done at 1.5X operating pressure to assure no leaks. This is then "bubble-leak checked" with soapy water to assure no leaks. When doing a fuel level control problem test, the test is done "wet." This means that the bowl is filled with fuel or alcohol to within 1/4" of the top of the bowl, which will raise the float to its operational position. The air pressure at the inlet is adjusted to the same pressure that your engine runs for actual fuel pressure (you need to check and know your fuel pressure for a good test). Any fuel control problem will reveal itself with bubbles in the float bowl. Once complete, the filled bowl is set up on some tall sockets and observed to see if any drips come out of the bottom of the bowl (from cracks or bad passage plugs). This does a very complete job of testing for leaks, and will assure that the bowl and fuel control systems are sound.
Lars
Your test results are indicative of a fuel control problem with the carb. This is not uncommon. Possible causes are:
.
Small piece of crap in the needle/seat
Defective needle/seat
Defective float
Wrong float installed (i.e., brass float or wrong year float for bowl)
Float needle clip installed wrong
Leaking seat gasket
Crack in float bowl
Excessive fuel pressure
If it were my carb, I would do a bowl pressure test to see if the problem can be duplicated and identified on the bench. I do these tests any time I have the hot-start complaint on a carb, and any time I do a fuel fitting inlet thread repair on the bowl. Here are some photos of my test setup when doing an inlet thread repair pressure test:
The seat, needle and float are installed and the float hinge pin is held in place with a flat bar and a c-clamp:
When doing an inlet fitting repair leak test, the test is done "dry" with no liquid in the float bowl. The float is held in the "up" position with a light spring under the float to close the needle/seat, allowing pressure to be seen at the inlet fitting. Inlet fitting testing is done at 1.5X operating pressure to assure no leaks. This is then "bubble-leak checked" with soapy water to assure no leaks. When doing a fuel level control problem test, the test is done "wet." This means that the bowl is filled with fuel or alcohol to within 1/4" of the top of the bowl, which will raise the float to its operational position. The air pressure at the inlet is adjusted to the same pressure that your engine runs for actual fuel pressure (you need to check and know your fuel pressure for a good test). Any fuel control problem will reveal itself with bubbles in the float bowl. Once complete, the filled bowl is set up on some tall sockets and observed to see if any drips come out of the bottom of the bowl (from cracks or bad passage plugs). This does a very complete job of testing for leaks, and will assure that the bowl and fuel control systems are sound.
Lars
Thank you, Lars, for the excellent write-up on testing the integrity of the fuel control system.
I'll order new gaskets and see if I can replicate your test procedure.
