1962 AFB fuel pressure
I have been using a fuel pump that delivers 6-8lbs, on a 1962, 300 HP. I temporarily installed a pressure regulator set at 4.5 lbs. The literature on the AFB says this carburetor is designed for 5 lbs, but does someone sell a pump with the lower pressure? The car runs well with the lower pressure and the exhaust smell is a lot easier to be around. Thanks, Ken
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Re: 1962 AFB fuel pressure
Kenneth,
Have you tried a rebuilt stock pump, the 4657 I overhauled with a kit from Paragon holds 5 3/4lbs at idle rpm speed. I can't recall any problems with the needle and seat not being able to hold that pressure but I agree 6-8lbs is to much.
If it's a screw together pump and you want to experiment try a 1/32" hole to relieve some pressure. Check the archives or google for info on the best place to drill the hole inside the pump. You may also be able to install a removable jet inside the fuel pump so you can experiment with the hole size to get the correct pressure. You could also just keep the fuel pump regulator. :-) -
Re: 1962 AFB fuel pressure
Do you suppose the pressure regulator might help those with heat soak problems? The fuel line from the pump to the carb is a major source of fuel heating up after shut down with no place to expand to but into the carb. I guess that was one reason for the by-pass line back to the tank on later carbureted emissions setups from the factory.
Stu FoxComment
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Re: 1962 AFB fuel pressure
Timothy,
I will try your suggestion about using a rebuild kit from Paragon to get the pressure to about 5 PSI.
Stuart,
My original problem was the engine acting like it ran rich at slow speed, like pulling a steep hill at about 20 MPH. I would have to put it in neutral and hold the RPM's at fast idle for about 10 secs until it smoothed out. If I ran the car in the garage, I could see occasional air coming into the sediment bowl, and the fuel level in the filter going lower. If I revved it to about 3K RPM, and dropped it to idle, it would not continue running, unless I kept it at a fast idle for about 10 secs, and the engine would smooth out. I replaced the steel line to the carburetor with rubber hose, from your suggestion in an old thread. The engine runs well now. I removed the Mr Gasket pressure regulator after reading about others experiencing leaking from these regulators.
Thank you Timothy and Stuart
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Re: 1962 AFB fuel pressure
Kennith,
How do the spark plugs look, I would probably start by checking float level and condition of the floats themselves and gaskets around the needle and seat area. Unfortunately you need to start double checking all the tune up items because it's going to be a process of elimination.
Could there be any vacuum leaks? IMO, I would not use a rubber hose for the gas line from the pump to carburetor. It's OK to insulate the steel line but if the rubber ever breaks you will have a fire for sure, use the factory set up.Comment
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Re: 1962 AFB fuel pressure
Timothy, I removed #7 J12YC. The porcelain is white, except for a black ring 1/8" around the top of the porcelain. The engine idled about 1/2 hour the last time it ran. Vacumn is 18" at 700 RPM. The float level was 1/4" and is now 5/16." Fuel pump pressure is 7-8 # at cold start, and slowly drops to 0 as temp comes to 180 degs. I ordered a fuel pump rebuild kit from Paragon, and hope it will give me a steady 5#. The fuel pump will deliver a pint in 15 secs.
Thanks, KenComment
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Re: 1962 AFB fuel pressure
As I recall, a number of factory installations on C-2's, later than 63, used a fuel hose from the filter to the carb. That's where I got the idea from and if it was good enough for the factory, well, then it was good enough for me. Certainly any one doing that would use hose for fuel applications, I would hope. As for the concern for leaks, if it is done right, I'd sooner trust it over a brass or steel flare fitting used over and over. That was another reason I used hose while I was trying to sort out my 3461S last year. I must of had it off the car once every week or so, or replaced by my standby 3721SB.
Stu FoxComment
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Re: 1962 AFB fuel pressure
Stu,
A rubber fuel line from the filter location to the float inlet is different than a line from the pump to carburetor inlet. The L-79 Holley's used a rubber line like you describe but a steel line from the pump to the filter where it runs in the front of the engine. It seems like the cast manifolds used steel fuel lines up to the carburetor, that's how my 67 w/300hp is configured.
Kenneth,
If I understand you correctly, the fuel pump pressure should not drop when the engine warms.
At idle the pump pressure should be maximum, the spring inside the pump is what maintains the pressure against the diaphram and the pump rocker arm lifts the diaphram up against the spring to maintain max pressure every time the camshaft eccentric pushes the pump arm. Double check if there is a suction leak in the fuel line from the tank or fittings. Just guessing here but there could be a valve not seated in the pump causing a leak down but I would think the problem would not just be after warm up, what pump is on the engine?
What AFB carburetor is on the engine and who overhauled it. It's possible there is a clogged air bleed making the engine rich.Comment
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Re: 1962 AFB fuel pressure
If Ken followed my advice/statement from a previous thread, as he indicated, then for certain he would have used the "rubber hose" from the filter to the carb only! I never would advocate running one from the pump to the carb. I, in all my 60 years messing with performance cars, did that only once and that was for test purposes using a clear in line fuel filter. That was on a new 83 Camero Z-28 H.O., which was running out of gas on WOT acceleration. I determined that to be due to the by-pass valve in the fuel pump opening too soon. I solved that by using a Holley jet in the by-pass as a restrictor in the hose back to the fuel tank.
Stu FoxComment
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