Sac '68 sport
Bronco Guru
fairly new, less than 3K miles, 302, RV cam, larger exaust valves and some porting, unilite, new wires and plugs, performer 289, and a 600 cfm vac. secondary Holley that I just rebuilt. C-4, 4.10's, and 32's.
Problem is I'm carbon fouling plugs (black soot but only on the rear half of the motor) at speed, 2800-3200 RPM when going from near sea level up to the mountains around 7000 ft. Runs fine down low but might be a little rich, and It doesn't seem to foul plugs once I'm up at altitude, but it doesn't run great up higher either, sputters and stalls out when I first put on the gas, idles fine then once I'm on it it seems to be ok, not great, just ok. Seems like it's running rich.
Jets, power valve???
Anyone know how to check what power valve should be in there, and would that change with altitude?
Is there a formula to how many jet sizes you should go down per Xft. of elevation or is it a trial and error thing?
Problem is I'm carbon fouling plugs (black soot but only on the rear half of the motor) at speed, 2800-3200 RPM when going from near sea level up to the mountains around 7000 ft. Runs fine down low but might be a little rich, and It doesn't seem to foul plugs once I'm up at altitude, but it doesn't run great up higher either, sputters and stalls out when I first put on the gas, idles fine then once I'm on it it seems to be ok, not great, just ok. Seems like it's running rich.
Jets, power valve???
Anyone know how to check what power valve should be in there, and would that change with altitude?
Is there a formula to how many jet sizes you should go down per Xft. of elevation or is it a trial and error thing?