Holley Carburetor leaks 67 350hp

[David P.]

I have a 67 327/350 very original roadster. Have owned since 1990. Rarely have I had any mechanical issues. I have been working on a high RPM miss and sent the original Holley off to be re-done. Put the carb on last winter and has ran great. Still have the high RPM miss but around town great. Last week went on a short ride and the car quit in the drive way and I could smell fuel.
Upon opening hood lots of fuel on the front of the carb. Mostly coming out of the rubber hinged plug on the front of the carb. Could not get the engine to run with out fuel pouring out.
What I have done so far:
Sent carb back and had the company check it out. It checked out with no issues. The rebuilder was Found from this forum and was great to work with.
Replaced the fuel pump which the carb guy recommended to see if too much pressure.
Tonight after putting carb and fuel pump on and starting I have the same issue. Car will run but fuel pouring out.
Any help will be appreciated before I have it towed to a shop.
Thanks.......

[Wayne W.]

Re: Holley Carburetor leaks 67 350hp

I have a 67 327/350 very original roadster. Have owned since 1990. Rarely have I had any mechanical issues. I have been working on a high RPM miss and sent the original Holley off to be re-done. Put the carb on last winter and has ran great. Still have the high RPM miss but around town great. Last week went on a short ride and the car quit in the drive way and I could smell fuel.
Upon opening hood lots of fuel on the front of the carb. Mostly coming out of the rubber hinged plug on the front of the carb. Could not get the engine to run with out fuel pouring out.
What I have done so far:
Sent carb back and had the company check it out. It checked out with no issues. The rebuilder was Found from this forum and was great to work with.
Replaced the fuel pump which the carb guy recommended to see if too much pressure.
Tonight after putting carb and fuel pump on and starting I have the same issue. Car will run but fuel pouring out.
Any help will be appreciated before I have it towed to a shop.
Thanks.......

If a Holley is flooding out of the vent hole, there is a problem with the needle and seat. Either it isnt adjusted correctly or its open and passing fuel. Could be either, front or rear.

[David P.]

Re: Holley Carburetor leaks 67 350hp

Is the repair of the carb something I can do or do I need to take to a shop?
How complicated is the carb work?
Manuals that would step me through the work......
Thanks

[Clem Z.]

Re: Holley Carburetor leaks 67 350hp

check to make sure the pin in the float bowl has not come loose and moved allowing the float to bind on the metering body. the gas coming out of the bowl vent says the needle/seat is not shutting off the flow of fuel. one thing to try if you don't want to take the carb apart is the remove the carb,dump the fuel out thru the bowl vents and then with the carb right side up blow air pressure of about 10 PSI in thru the fuel inlet on the front bowl. this will allow the floats to drop to the bottom of the float bowls and the needle/seat will be wide open and if there is any debris in that area it will blow out.

[Wayne W.]

Re: Holley Carburetor leaks 67 350hp

Most of the time when this stuff happens, there is another root cause. You need to check the tank, lines and filter for rust, water and debris.

[Gerard F.]

Re: Holley Carburetor leaks 67 350hp

Is the repair of the carb something I can do or do I need to take to a shop?
How complicated is the carb work?
Manuals that would step me through the work......
Thanks

David,

Unfortunately, a 3810 has non-externally adjustable floats, and you have to take the fuel bowls off to adjust the floats. The only manual I've seen that has the correct adjustment procedures for a 3810, is the 67 Chassis Overhaul Manual (not the Service Manual).

As Clem says, the floats could be loose on their pivots, and could be hanging up in the bowl on the metering body or plate, or on the bowl itself. Or the floats are just not adjusted right. Are you using the filter in the front bowl?

It is not hard to pull the fuel bowls and adjust the floats, with the right manual.

However that high speed miss could be another problem in itself, and could even be a timing or vacuum problem, or a venting problem with the carb.
If it's a venting problem with the carb, you ought to send it back to the restorer to check through all the venting passages.

[Michael M.]

Re: Holley Carburetor leaks 67 350hp

David, I had the exact same problem with my 3810 earlier this summer. I talked to the Holley people and arrived at the conclusion it was the needle and seat not closing properly for some reason. There was some speculation that it might be the affect of ethanol on the Viton needle tip but nothing conclusive.

I ordered the recommended replacement (Holley #6-510) needle and seat – it’s a .110 vs. the original .101. Replaced the bowl gasket, blew all the vents with an aerosol carburetor cleaner and replaced the fuel filter. I checked the float setting but it was good and no wear or binding could be detected. I have not had a recurrence since, so I believe one of those things corrected it. Good luck.

The Holley website has a wealth of information - manuals and instructions.