Quote:
Originally Posted by Phx Mike
I think you are making a good call on the compression ratio. Mine is at about 10:1. I am running a Comp Cams custom grind with 242/248 intake and exhaust durations (@0.050") and lift at 0.642/0.631 respectively and 112 degree LSA. Edelbrock heads with stage 3 porting and the big valves (2.25/1.75). No pinging on 91 octane but it does diesel when I shut it down (timing at 12 degrees at 800 rpm idle and about 38 degrees fully advanced at 2750 or so). If I run a little 95 octane in it the dieseling goes away...it really likes octane level at or above 92-93. With a similar setup and 9.5 to 1 you should be just right I think.
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Yes, my 428 had the dieseling problem too.
Good to hear feed back, because my builder is wanting to go that way and being old school I always think higher compression is a good thing. He is educating me on today's fuel and the effect on these older engines.
Cam is a Elgin Pro stock # E 963 P. Cam lift .292, Duration 300 and valve lift .505. It Same numbers int and exh