Holley Carb Problem.

[TRIMM MANN]

I have a Holley 625 CFM with vacuum secondaries.
Here's my problem:
Engine runs perfect. I shut down and then try to start back up and the primaries flood over. Pull the air cleaner off, hit the gas once and gas keeps dumping in. If the engine sits for any amount of time it starts fine.
Sounds to me like a float problem. Most of the Holley's I have seen have a float adjustment screw on the top and a sight screw on the side, not this one.
Should I have the carb rebuilt or is it an easy adjustment?
Thanks

[Moneypitt]

It sounds like perculation, fuel in the bowl is heating up after shut down. Or fuel in the line is subjected to a heat source, and overpowers the needle and seat. If the float were bad it would flood all the time. The adjustment is internal, float level is controlled by a "tang" the pushes against the needle and shuts off the flow. What is the fuel pressure while running, and does it go up after shutdown? If this problem is hit and miss, it could be a result of dirty fuel, but that would affect the secondaries as well. I would look at the float, and the needle and seat. The needle tip is a rubber type point that must seal in a tappered seat. The needles do get hard, and no longer seal, but again this would be a continuous problem. Look at the heating of lines, and even the intake exhaust crossover causing perculation.............MP

[SmokinLowriderSS]

I'm with MP on this one. If you knew what your fuel pressure was, and if it changed any, it would help. My first thought was remaining line pressure bleeding past the needle & seat assy overfilling it after shutdown stopped drawing fuel off but, I hadn't considered the possibility of heat. His idea has a higher likelihood than mine does, same basic result tho. The boilover will evaporate after a while and you never know you have the problem, only on teh short stop does it flood it noticably.
You may need to insulate or reroute the fuel line, and/or install a fibre spacer to insulate the carb more from the manifold.

[TRIMM MANN]

Thanks for the help.
It's on a 1972 Vette which I have had for 25 years. I put the Holley on it 15 years ago so I am guessing some dirt might have gotten caught in the needle and seat. The car has a tendency to sit for a while also. I figured it's time for a rebuild.
Thanks again.

[Moneypitt]

Dirt in the needle, is like what happens in Vegas, it stays there. The pressure of the float against the needle will not allow the dirt to fall out. You can however: with rubber fuel line, "pinch" off the fuel supply while idleing, let it almost run out of gas, and then release the "pinch", the in rushing fuel will clean it out because the float has dropped and the needle is free to fall away from the seat, freeing the dirt. With steel lines, use a rag to catch the fuel, (ENGINE OFF), and remove a lower bowl screw, drain away the fuel, this lets the float drop as above, reinstall bowl screw. It will be a little hard starting because the bowl is empty, so don't backfire the carb and wipe out a power valve. That said, I don't think dirt is your problem because you only flood after shut down..........Does this car have a "heat riser", the butterfly in the head pipe right below the manifold, one side only, these close cold, divert exhaust under the plenium to heat it up for cold start driveabilty. If it is stuck it could be heating the intake all the time and create the problem you're having. There is a counter weight that swings against a bi metal spring, when hot the couterweight opens the butterfly because the spring is weak hot. Just a possible idea...........and these rust up, especially in a vehicle that gets started and not totally warmed up regularily, like a toy Corvette...........MP