Many thanks for the responce to my question/problem of backfiring thru the carb as a timing chain problem (it was). Now that the engine is out, I'm thinking rebuild. I'd like to hop it up a bit, but not so much it's a pain to live with. My questions are, what duration and lift cam range would you suggest (not solid lifter or roller type) and can I get away with 10 to 1 compression pistons or should I stay with 9:1. It's a 72 Pantera with stock heads, torker manifold & 650 Holley and headers. Thanks again for the help. Oh, and one more thing, what should be maximun timing advance at say 3,000 rpm (no vaccum. Should advance be all in at that rpm range? What would be maximun advance degrees for these engines.
Original Post
Think of the 351C as a short-stroke big- block. Thus one can use far more duration and lift on a 351C than, say, a 350 Chev. But first, be honest with yourself about what you're gonna do with the car, then call the Crane, Isky or Comp Cams tech lines and ask the REAL cam experts. Include their recommended valve springs and lifters in your choice of cams. As for compression, 9:1 with open chamber heads is max, unless you've got a stash of high-octane gas around somewhere. A radical cam will reduce pumping pressure enough to allow 9-1/2:1 with closed-chamber heads, and aluminum heads allow 10:1, all on 92-octane. 351C chambers are pretty efficient so you don't need monstrous amounts of spark advance. 10-12 degrees initial and 34-36 degrees total (initial+centrifugal+vacuum), with most of it in by 2700 should make for a nice ride. After 38 degrees total, you risk detonation & losing a rod bearing; dyno tests on SB Fords have repeatedly shown that power drops off with increasing advance; some combinations show more power at 32 total than at 36.
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