[Gregski]

alright so the whole point of getting a vacuum gauge was to tune the carburetor to have the highest vacuum at idle, so here we go


below we only mess with one thing at a time so in this case we were only turning the Idle Mixture screws to change the idle mixture, we were basically allowing more fuel in to see what the impact would be on vacuum

undesirable results are in red


-TIMING- - - - - - - - - - - - - - - - - - - - - - - - - - - IDLE - - - - - - - - -IDLE - - - - - - AFR - - - - - - AFR
ADVANCE - - - - - RPM - - - - - VACUUM - - - - - MIXTURE - - - - - - SPEED - - - - - LEFT - - - - - RIGHT - - - - - - - - - COMMENTS

- 10° - - - - - - - - -590 - - - - - - - 15" - - - - - - - -1.50 turns - - - - - -1.5 turns - - - - - 13.5 - - - - - 13.6 - - - - - this is where we started (carb bench tunned to factory specs)

- 10° - - - - - - - - -580 - - - - - - - 15" - - - - - - - - 1.75 turns - - - - - 1.5 turns - - - - - 12.2 - - - - - 12.2 - - - - - we richened the mixture by quarter turn out (vacuum stayed the same at 15")

- 10° - - - - - - - - -540 - - - - - - - 13" - - - - - - - - 2.00 turns - - - - - 1.5 turns - - - - - 11.4 - - - - - 11.6 - - - - - we richened the mixture by another quarter turn (vacuum dropped to 13")


ok, alright, clearly we are going the wrong way, the mixture is getting richer and richer, ok now we know (and we couldn't lean it out any more cause that would drop the RPMs below 500 and the truck would die)