Holley carb. problem
Thread Starter
Instructor
Joined: Jun 2003
Posts: 114
Likes: 0
From: Sydney NSW
Holley carb. problem
Hello Im having a problem with my 600cfm /1850 vac .sec. it seems to dribble fuel out of the secondies out of the air horn but it seems to happen when stuck in bumper to bumper traffic but runs fine other times I have a holley street chrome fuel pump on it I have a new needle and seat and have adjusted the float level just on the thread line at the sight hole this problem only happens when it is prolonged idleing in traffic ?do you think you that the holley street pump has to much pressure all should I put the stock fuel pump back on? thank-you
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Carbs are very sensitive to fuel pressure and you could have just a bit too much for the needle and seat. They usually do fine at four psi. It gets iffy at pressure above that. Some do fine at up to seven psi, but that's pushing it. But you may be experiencing some fuel percolation in the rear bowl. I'd drop the float level a bit more and see how it responds. The only reason for fuel to be dribbling out of the boosters is the fuel level is too high. Whether thats float level, percolation, or pressure is a matter of your troubleshooting skills.
Advanced
Joined: Jan 2008
Posts: 99
Likes: 0
From: Chesapeake Virginia
If you google holley carbs, you can get the number to their tech line. The guys there are very patient and helpful. I'd call them and run it down.
I agree that if you're pushing more than 6-7 psi, you may be overloading its capability and it's simply overflowing.
I agree that if you're pushing more than 6-7 psi, you may be overloading its capability and it's simply overflowing.
Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
You need to check the fuel pressure.
Connect a fuel press gauge up and tape it onto the windshield so u can see it then drive around a bit. Fuel press should be <7psi all the time. Also low needle seat spring press (from fuel line press too high/aftermarket fuel pump). Power valve maybe (torn open inside)?
Good luck,
cardo0
Good luck,
cardo0
Race Director
Joined: Dec 2004
Posts: 15,008
Likes: 2
Although each application is unique, I would think heat would make the primaries boil over first.....
Put a fuel pressure gauge and see what you're getting. Back when I remanufactured carburetors for a living, I used to flow check Holley's @ 10 - 12 psi. Anything above that will over power the N/S.
Put a fuel pressure gauge and see what you're getting. Back when I remanufactured carburetors for a living, I used to flow check Holley's @ 10 - 12 psi. Anything above that will over power the N/S.
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Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Although each application is unique, I would think heat would make the primaries boil over first.....
Put a fuel pressure gauge and see what you're getting. Back when I remanufactured carburetors for a living, I used to flow check Holley's @ 10 - 12 psi. Anything above that will over power the N/S.
Put a fuel pressure gauge and see what you're getting. Back when I remanufactured carburetors for a living, I used to flow check Holley's @ 10 - 12 psi. Anything above that will over power the N/S.
I see you work at the Department of Redundancy Department.
Race Director
Joined: Dec 2004
Posts: 15,008
Likes: 2
No reason in particular. I guess what I meant to say is there is no reason why the secondaries should be seeing any more heat than the primaries, unless we're dealing with an earlier model with the heat transfer slot in the manifold which would put more heat to the primaries. Doesn't seem to be the case though, since he has an 1850 square bore Holley.
Race Director
Joined: Oct 2000
Posts: 15,009
Likes: 79
From: central FL, near the beach.
put a pot of water on the stove.
when it boils, add a little cool water.
Stops boiling, right?
Same thing idling in traffic. front gets fresh gas, back doesn't. back boils
when it boils, add a little cool water.
Stops boiling, right?
Same thing idling in traffic. front gets fresh gas, back doesn't. back boils
