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This is a continuation of another post on this board, but I ran across some info that I felt prompted starting another thread. For those of you who are looking for a little more from you LS-6 or L-72 build up, read on...
In the earlier thread, Jim Lerum posted the compression mapping for a 454, which looked like this: Intake valve closer/ Compression IVC 68 degrees = 11.54cr IVC 69 degrees = 11.64cr IVC 70 degrees = 11.74cr IVC 71 degrees = 11.86cr IVC 72 degrees = 11.96cr IVC 73 degrees = 12.06cr As Jim says, "this formula involves % cylinder volume vs crankshaft angles". Well, at the time, he didn't have the numbers for a 3.76" stroke, but I have since ran across them. Here is what I found: Intake valve closer/ Compression IVC 68 degrees = 11.60cr IVC 69 degrees = 11.71cr IVC 70 degrees = 11.81cr IVC 71 degrees = 11.91cr IVC 72 degrees = 12.03cr IVC 73 degrees = 12.14cr What these numbers should be telling us is what the target compression ratio should be given a certain IVC (intake valve closing). Well, Jim guessed the IVC of the #3863143 cam to be 70 degrees, and I used the same range of numbers to map the 427. BUT, one problem I'm running into is finding the correct "seat to seat" timing of the cam. I've found them measured at .006", .015", and .050", but they don't seem to match up with what I need. So, anyone have a 3863143, a degree wheel and a cam doctor? [img]/ubbthreads/images/icons/grin.gif[/img] |
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