I got some time this weekend to test a few different main jet/pvcr combinations and I am now more confused than I was when I started. I tested the following (main jet/pvcr/hg below my 9.5 pv/cruising A/F 30mph-55mph): 62/.059/16+ (13.8-15.0) 58/.065/17+ (14.4-16.0) 64/.065/13.8-14.4[target] (13.6-14.4) 60/.069/16+ (14.0-15.0)
What I found was that the larger the main jet the richer the A/F with the pv open. This makes sense but the richer the jet, the richer my A/F was at cruise. The 064/.065[target] worked great at accel but the cruising A/F was too rich. The 060/.069 worked great at cruise (14.0-15.0 from 35 to 55mph) but the accel was 16+ with pv open. I am going to test a more aggressive pump cam to see if the 16+ readings will get richer (low 14's) but if not, then I have a .071 pvcr to test too. This is how the current 60jet/.069pvcr/.060iab combo showed in 70 degree weather: 30=14.0 35=14.6 40=14.6 45=14.6 50=15.0 55=14.4 60=14.4 3500rpms=14.4 (best so far but too rich) 4000rpms=14.4 (best so far but too rich) I was real happy with the small A/F spread but when the pv kicks in, I am getting an A/F ratio of 16.0 plus.
Note: I achieved almost the same A/F readings with 62/.059 combo but slightly leaner which is my goal, but the 3500/4000rpm A/F showed 14.2 though. This combo still showed 16+ below the 9.5pv rating at low speeds.
I am testing with a white primary pump cam and I might jump to an orange to see where the A/f goes too during accel. The next larger pvcr that I have is the largest QF had which is a .071. The above is still slightly rich for my liking but I will swap the .060" iab's for a set of .064" to see if that leans it out just a tad.
Any ideas other than the larger pump cam and the richer pvcr to increase the below 9.5hg reading? Note: I did make a couple of 12hg readings they were all sligtly richer than the above 9.5 readings.
""If its continuing to get leaner below the PV opening vacuum then the PV is probably not opening when it should be."" This IS what is happening at low speeds (30-45mph or so) before the tranny kick down. It appears that the mains are not helping at lower speeds and this is why I am thinking of using the pump cam.
