Thread: Carb Issues on drag car

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Originally Posted by zaneyboi

Sorry for the late reply I have been away. But I do get a constant 6-7 psi on my fuel pressure gauge. It is a head scratcher for sure...

It's not really a head scratcher, you have a good setup for a track only, idle to wide open throttle engine. On the street, you are going to have hesitation, bogging, and will not be happy if that is your long term plan to drive on the street 90% of the time, and the drag strip 10% of the time. You will not be able to tweak the carb to serve both purposes, and still have good passes on the track.

Bill S.

Originally Posted by mrmustang

It's not really a head scratcher, you have a good setup for a track only, idle to wide open throttle engine. On the street, you are going to have hesitation, bogging, and will not be happy if that is your long term plan to drive on the street 90% of the time, and the drag strip 10% of the time. You will not be able to tweak the carb to serve both purposes, and still have good passes on the track.
Bill S.

Originally Posted by Dave Severson

Automatic or manual transmission, if an automatic what stall speed converter? There really is no way to tune one carb to make it perform equally well on the street and the track, an EFI system will come close to doing both but even then you would need to get your lap top out and do some "tuning" unique to either operation. Also, you didn't mention fuel pump, regulator, or fuel line components, the amount of fuel flowing to the carb is equally as important as the amount of fuel pressure!

I don't disagree at all that it's going to be all but impossible to "detune" for smooth street operation on a carb optimized for the strip, and the questions Dave poses are good info to know too, but to me that doesn't address what would cause the A/F ratio to go from "good" (I assume that's in the 11.5 to 12.5 range) up to 18.0 while idling at a stop light, then after being shut down for five minutes being "good" again for rest of the trip to his buddy's, and then all the way home later. Something had to either starve the fuel or dump in a bunch of excess air, then correct itself with the shutdown. The Holley Street Avenger on my SBC says fuel pressure should be 5-7psig, so his "...constant 6-7psig" is dead on. No answers, but I don't think we're addressing the problem yet. Just my $0.02, and still scratching my head.....