I have installed a brand new Summit Racing 500cfm carburetor recently and found a couple of quirks... 1. The factory settings should be checked before firing up the carb. My mistake for trusting Summit, but the idle set screw was so far out of adjustment that at idle the engine was at 2500 rpm. 2. After getting things sorted out and driving the car for 20 minutes, things were running very, very good. It "felt" better than my Holley 1850. Welp, after I parked it in the garage I found this the next day... (yes, I have clean fuel and a quality filter between the pump and the carburetor) Summit Carb by danman55 posted Feb 1, 2023 at 11:38 AM Summit Carb by danman55 posted Feb 1, 2023 at 11:38 AM The float level could not have been out of adjustment because I never had any issues with flooding, etc but it was so full even the screw and nut to adjust the float was wet. I did remove the lid and spray some carburetor cleaner - seems to me that the needle was not seating correctly. When I inspected everything I found no junk or no crud so I have no idea what was going here. Has anyone else run into issues with Summit carburetors?
First thing I would check is the fuel pressure, 4-6 psi should be about right, so many fuel pumps are now offshore made and on many forums they are finding a lot of off the wall readings. I have seen guys stating "but it's a stock pump" and then finding out the pressure is 9 psi plus, you may want to add a regulator. I would give the Tech guys at Summit a call, you may not be alone on this.
Jeff, good thought and if I did not have a pressure gauge I would be with you on that one too. My gauge is reading just a tick over 5 psi - same pump I had with the Holley. We will run it when the weather breaks - lots of salt on the road right now, and see what happens.
danman, surprised you bought a 500 when so many recommend the 2 bigger ones. I too ordered one to put on the Blue Thunder manifold. I have not done yet the swap yet. For those who wonder about Summit Carbs. Dave Friberger had a Test on a 383 Chev engine testing a Summit, Edelbbrock, and a Thermoquad looking carb and the Summit came out on top. I chose the Summit for the annular discharge boosters and it’s under 3000 rpm performance where most of us use our engines.
I have heard of that issue caused by improper fuel tank venting, next time you park it loosen the gas cap and see if the same thing happens after it is parked over night.
I thought Fords of our era had separate 1/4” vent lines and not a vented cap. I’m guessing this was because of the cap being behind the license plate. (Not on wagons or sedan delivery) I have heard of them being plugged.
I ran a Summit 600 cfm on my y block for about a year. It ran great but I was constantly messing with it. Fuel level too high, rich idle that I could never lean out,etc,etc. I ended up selling it and putting on a Quick fuel sl-1957 e. I'm alot happier with it.
One thing I forgot. Be careful when taking the top off. I took mine off once to change the jetting and inadvertently bent the float arm. This caused the level to be too high.
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