Hey guys. I have 2 different 750 holley carbs. One is a 3310 VS and the other is a double pumper mechanical. Both of these carbs I installed a full rebuild kit. New everything. I put them on the car and gas starts shooting out the vent. Brand new needle and seats. Floats adjusted with the 1/2 drill bit. Never had an issue like this before and for it to happen on 2 carbs doesn't seem right. I did a bunch of searching and everyone says dirty needle but these are new and have been carb cleaned and blown out. Checked the Floats for leaks and are fine. Brass center hung in both. Any thoughts? I am stumped... Sent from my SM-G930R4 using The H.A.M.B. mobile app
If you didn't have the problem before the rebuild and now you do with both carbs I'd say its something with the rebuild kits and most likely the needles and seats. Try swapping back to your old needle and seats on one of the carbs and see what happens. Remember that these days new isn't necessarily good.
Running a holley mechanical pump. Pressure is about 7. The rebuild kits were 2 different brands. One from holley and the other a quick fuel. I have a holley street avenger on the car now with no flooding issues so I think pressure is not the issue. Sent from my SM-G930R4 using The H.A.M.B. mobile app
Yea I checked the rings for nicks as well. Is it possible to get vacuum into the bowl? Sent from my SM-G930R4 using The H.A.M.B. mobile app
My thoughts are that your setting the floats to high! Nominally there is approximately 1/16th of an inch of thread on the top of the seat shaft visible looking down onto the bowl! I always set the floats whilst the bowl is off of the carb body and whilst upside down during a rebuild! Needles lift or purge from the seat just below 7lbs pressure especially when you have a little volume behind the pressure! Cheers from Aussie Sent from my iPhone using The H.A.M.B. mobile app
Never ran into the problem of to low a fuel pressure. The seat height all depends on where the tang for the float is that will adjust the total height or lack of. Good place to start with float adjustment is to turn the bowl upside down and make the back of the float even with the float arm mounting screws., then check and adjust from there. good luck
just did one over the weekend. It spewed fuel right away, front & back. I pulled the fuel level plugs and readjusted, bounced the car some to double check, fired her up and adjusted idle speed and mixture and hit the road. Doing the visual adjustment prior to installing the bowls didnt work out so well, using the plugs always works for me. No more issues. that carb had the side hung floats, they dont seem to hold the pressure of the center hung floats.
No more than 5 psi and we set the float level with the engine running in the car. There is a tool that does it, looks like a valve gap lash tool. The visual sight plugs should not be used for normal running. Good luck.
adj with the bowel side plug OFF till it is NOT running out but IS right there at the bottom of the side hole. -n- sometimes a smidge lower
I figured it out! I had the metering block gaskets in the wrong side. One side has a small hole and the other has a cut out. Flipped them and runs great. Sent from my SM-G930R4 using The H.A.M.B. mobile app
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