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?

[Gerard F.]

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

Mel,
I had a similar problem with my 67 Holley after I had restored it. I finally found that the secondary float was loose in its pivot and it would rub against the secondary metering plate when driving. The simple solution was to bend the float toward the front of the fuel bowl and away from the metering plate. worked for me and ended my flooding problems.

Jerry Fuccillo

[William F.]

As in another post, remove float, put in a jar filled with gas and see if float sinks as it will if it has a pin hole and filled with gas. Can happen even with new carb or new float.

[Joseph S.]

Mel,
Had a flooding problem with my '66 list 3370 Holley a year or so ago. Problem traced down to a slight warpage (maybe corrosion)around the idle port holes in the front metering block. Fuel would saturate between the metering block ports. No external leaks from the metering block.

Tried different gaskets, double gasket but they were only temporary fixes. New front metering block from Chicago Corvette was the perminent fix

Joe