[yankeeralph]

I need some cam expert help.

I presently have some slight pinging under light acceleration with a Comp Cam High Energy 268H cam. Installed in a 68 YC 400 with stock 15 heads, +.030 on cylinder -- I think compression may be higher than the 9.0 the builder was shooting for since he was not that familiar with pontiac engines. Have timing at 8 BTDC, 24 with vacuum advance and 32 total at 3000. Under hard acceleration I cannot detect any pinging, quite possibly because of all the other noises. Under light acceleration and slight/heavy load (going up incline)I stll hear some pinging, but not excessive like my 92 ford truck.

My problem is that Comp Cams states that if the compression is over 9:1 then the high energy cam will contribute to pinging and that i need a different cam -- like the 270H Magnum -- says it helps because of longer duration? What gives?? Will the 270H help or is there a better choice. This is strickly a street driven daily driver.

Setup: 68 400 block +.030, (CR between 9-10 but unsure), sil-r Lite Pistons (Brand spelling), stock rods and #15 heads, recent rebuild with new Comp dual springs, roller rockers, Edelbrock Intake and carb, 2000 Stall Holeshot with a TH350 transmission, 3.42 posi rear. Running 93 pump gas and want to keep it that way. Hei distributor with AC R43 plugs gapped at .045. 165 deg thermostat with 4-row rad. Cooling is great now that I fixed some leaks.

Car runs good and strong.

Please help! Do I need to back timing down some more and suffer performance, or is the new cam a better choice.

Thanks