Holley jet correction

5150

I was looking at the Holley jet correction for atmosphere chart,and I,m confused. Is the corrected jet number caculated at the bottom of the chart the jet I should be running, or is that what my "68" main jet is "acting" like? Thank you.

tsanchez

Well if at sea level you have a 70 jet then as the altitude goes up you will need smaller jets. I would say between .5 -1 jet size reduction per 1000 ft altitude change

Mudrat

tsanchez wrote
Well if at sea level you have a 70 jet then as the altitude goes up you will need smaller jets. I would say between .5 -1 jet size reduction per 1000 ft altitude change

Seems like a lot for every 1000 feet :shock: I go between sea level and 3000 feet and I do feel a loss of power, but a whole jet size?? :-|

AMX69PHATTY

Understanding is one Holley Jet number change is 3% change in fuel per jet, I think, or 6% for a pair. Funny thing is tolerance is +/- 1.5% on standard Holley jets so in theory it's possoble to change by 1 jet size and have no change in fuel delivery. Tolerance is tighter on Holley Close Limit Jets, about +/- 0.6% Standard Jet part numbers are 122-xx Close Limit Jet part numbers are 122-xx2