Flooding Holley

[Mel S.]

I had my Holly carb from my 70 LT1 refreshed this winter. All internal parts were replaced. Last week I finally had the time to install the carb and go for my first ride this year. It was a short 20 mile ride and all went well. A couple of days later, I tried to go for another ride but the car started and then died immediately. When I removed the air filter, it was saturated with gas along with the carb. With the carb exposed, I cranked the engine over and gas came shooting out of the front venture tube. I assumed a stuck needle and seat. I removed it, did not see anything wrong, but sprayed it with carb cleaner anyway. Reassembled and had the same problem. When I removed the screw from the side of the bowl, the fuel level was below the screw hole. I had an unopened rebuild kit for another Holly that I have. I put in another new needle and seat from that kit but have the same problem. I also removed the bowl and check the float to be sure that it did not have any gas in it. Any help would be greatly appreciated.
Mel

[Keith W.]

I’m certainly not an expert but does the float have a hole in it not allowing the needle and seat to function correctly? Or maybe something to do with the power valve?

[Dave B.]

Did you raise the floats to the proper height? Check the accelerator pump setup and adjust?

[Patrick B.]

Has the fuel pump been changed since the last time the carb ran without flooding. I have experienced the same thing on a 67 small block, and the problem was a new fuel pump with too much pressure.

[Mark M.]

As Patrick mentioned fuel pressure could be too high, should be 5-6 1/2. I would check the o ring on the needle assembly. That should be a center hung float and the needle should screw right out.

[Winston M.]

I had this problem when rebuilding the original Holley four barrel on my friend's 70 Shelby GT500 Mustang.
I kitted it three times and all it would do is flood. I finally found the answer to my problem on the internet. The
power valve that was in the Holley rebuild kits had too long of a tip for the 1970 metering blocks and they would
bottom out and get jacked open. I found the correct shorter power valve on the internet and problem solved.
I don't know if the Holleys on your GM application have this problem, but it sure sounds like the problem I had.

[Timothy B.]

My thoughts are to check carefully the bowl for damage where the needle and seat seal to the bowl. There is a leak in that area allowing the fuel flow to run out of the vent.

[John F.]

You said the fuel level was below the side screw hole. Was that with the engine running?