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#1 Fuel level in SU's (Another carb query!)
Posted: Sun Mar 09, 2014 1:02 pm
by skodajag
For some reason I still can't explain, when I set the fuel level on my SU's as per the book (with 7/16 bar) the carbs visibly flood. I've checked that the floats aren't holed, and that the needle valves are seating properly. So can anyone advise me on the following: with the ignition on (fuel pump active) pistons and needles removed, and the top of the jets set level with the bottom of the carbs, where should the fuel level be in the jet? I'm assuming about ? of an inch down. Is that correct? Thanks in advance!
#2
Posted: Sun Mar 09, 2014 2:27 pm
by Moeregaard
Are you running the stock SU pump, or an aftermarket unit? This sounds like a case of excessive fuel pressure.
#3
Posted: Sun Mar 09, 2014 6:22 pm
by 1954Etype
Just had the same problem set the float height lower until you achieve no flooding.
#4
Posted: Tue Mar 11, 2014 1:43 pm
by ChrisC
Yup I agree with Angus....
I adjusted the floats so that the fuel level in the jets was the same acrosss all 3 carbs rather than being particular about using the 7/16th bar...
#5
Posted: Sat Mar 15, 2014 10:02 pm
by skodajag
Thanks for the replies. I 'm pretty sure the pressure is indeed too high because the front carb floods whatever. Not sure what pump is fitted but it's non standard. So I'm going to get a fuel pressure regulator - filter king or some such and start over.
#6
Posted: Sun Mar 16, 2014 1:37 pm
by Moeregaard
Most aftermarket pumps do their jobs too well. SU carbs are perfectly happy with 2.0 PSI. I encountered this problem years ago, when the SU pump quit and I dug a Facet pump out of my box-o-bits and installed it as a temporary replacement. Experimenting with lowering the float levels, I found that fuel surge and starvation during cornering became a problem if I deviated too far from the 7/16" specification.