9.5 is working well for me, it all depends on your cam profile and final gear ratio what PV you wind up with. I was surprised to find my vacuum stays above 9.5 even while cruising at 80 mph, 11 while cruising at 60! I can actually feel the PV open with just a slight increase in throttle. This is due largely because I'm currently running some fairly heavy springs on the vacuum secondaries. I didn't want them opening to soon and interfere with my continuing diagnosis of the jets and PV settings.
Bigger jets if your running a lower vac setting on the PV, makes sense to me. You would be relying primarily on the jets to "tack up the slack" before the PV opens. Hmmmmm,,,,,,,, an interesting thought there and may be more fuel efficient.
Crisp accelleration with no hestitation and/or backfire, THAT is the goal. Was real good when I FIRST ran the 68's. Now after a few days, I've got fouled plugs!
63's tomorrow.
Insulated the fire wall today, WOW, no more burned up tennis shoes for me. WAY cooler.
On that note: My exhaust temperatures are definitly higher than I had before, which is perplexing. I was running 12.5 to 1 with a radical cam and WAY RICH before. Now I'm at 9.8 to 1, much milder cam and rich or lean, the exhaust IS hotter than before. Could be the "squish" factor I think, I moved the piston UP .030 in the bore at the same time I dropped compression (new custom order blue printed pistons).