I don't know too much about holley carbs, but the problem I am having is that, with the car running, gas comes out of the tubes that stick up a little from the top of the carb...
What may be the problem? Can a bad power valve do this? (I was under the impression that a bad power valve would dump too much fuel into the barrels...)
Maybe too much fuel pressure or bad needles/seats?
Do you know what the pressure is?
If not can you tell us what kind of fuel pump you are running? Stock or after market mechanical, electric. Just so we we would know what kind of PSI to expect.
I have read of this problem before, unfortunately I don't remember the solution. It may be stuck floats all the way up. Most Holley carbs have a screw on the side of the bowls. You remove the screws and gas comes out then the floats are to high. Anyway if I am wrong then some one will see this and give you the correct procedure. Could be too much fuel pressure Moon makes a gauge and you should run around 7 lbs. Summit sells a regulator. If you have been running this combo for a while I would not think this is the problem
Sounds like a bad needle and seat or dirt in the fuel bowl and needle and seat, or a heavy float or to much fuel pressure, or the fuel level isn't set right. You need to take the fuel bowl off the carb and check it for dirt-make sure you have a good fuel filter installed between the pump and carb. Also look at the needle and seat and check for wear and dirt and varnish. Check the needle and seat sealing ability by blowing throught the fuel bowl inlet and moving the float up and down-this should open and close the circuit. Adjust the fuel level by turning the needle and seat assembly so the fuel is level with the bottom of the sight hole.
If the float level is adjusted correctly the solution is simple. take the butt end of a large screwdriver and smack the needle adjuster several times with the engine running. It is very common to get garbage in the needle and seat. Work on a ton of holleys and this works every time
I don't know the fuel pressure. I will stop this afternoon by the local part store and see what they have for pressure testers and regulators...If recall correctly, last time I looked they had a mr Gasket regulator for cheap, so I may buy that.
My pump is mechanical, it was on this engine when I got it. There was a sticker that said who made it, but that has since warn off, there is a big AC cast into the front side of the pump. (Motor, by the way, is a 350)
I just slapped this holley on last night, I had an edelbrock on but it seemed to be flooding...(the fact that both carbs do this makes me think fuel pressure) the interesting thing is, the guy before me who had this carb had the same problem, me and him tore this thing down twice and couldn't find anything wrong then, we replaced with and edelbrock and his van works fine.
Although, we are in fairly similar situations, we both swapped out 4.3 liters in an 87 (his an astro, mine a caprice) for 350s...
Any way, I'll see about fuel pressure this afternoon, and see what I find there. Thanks for all the replies!!
Anyway, I tried a fuel pressure regulator, set it at 3 psi, and fuel still comes out of those tubes (vent tubes?) on the Holley.
I tried tapping on the float bowls, but that didn't make any difference. I don't really want to tear this carb apart, so I think I am going to give it back to the guy I got it from...
So I swapped the edelbrock back on, and it still seems to be flooding too!
Just buy a rebuild kit for, Holleys are Probably one of the easiest carbs to rebuild a couple of body and bowl gasket, valve seat and power valves done.
I tried tapping on the float bowls, but that didn't make any difference. I don't really want to tear this carb apart, so I think I am going to give it back to the guy I got it from...
The carb doesn't need to be disassembled to replace the needle and seats,
the carb doesn't need to come of the engine. Just unscrew them and screw
in the new ones then set the fuel level.
1. As everyone as pointed out the fuel pressure can be too high. ...Should be 3 to 6 pounds
2. Stuck needle stuck off the set. ...but bumping the side of the carb should free it up.
3. Incorrect float adjustment(my choice)! ...Be sure your float is set correctly, where gas level is only up to the center of the window on the side of the carb.
One thing I can tell you it's not the power valve. The power vlv. is an "extra door" way for gas to get to the engine when you floor the gas pedal. You shouldn't have a problem with this UNLESS you have a real big cam with a lot of duration on it. Normally the vacuum keeps this "doorway" closed, until you floor the gas pedal. Now with W.O.T. your vacuum drops down to where the power vlv. opens up dumping fuel into the engine. And as the RPMs build up and the vacuum builds back up it then closes the power vlv again and the gas is delivered thru the normal gas circuit. IF the power vlv. is bad, the engine would be running very rich, but fuel won't be coming out the vent tubes. HOPE this helps! Good Luck!
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