Hi all, Terrick here with an enquiry to those more learned in camshaft
theory than I.
My Kastner S4 factory race cam has a "hot" valve clearance of .020. Yes,
it sounds like a worn out industrial sewing machine that goes really fast,
and it does go really fast but not off the line with that LeMans gearset.
In degreeing the cam, I noticed a HUGE difference in valve timing depending
on the checking clearance I used which, of course, simulates the rocker
ratio and all other factors so that the valve opens when the stated timing
event occurs.
Here's my question.....\
Since the clearances are taken HOT, and since the clearances cold to hot
dont change more than a thou or so anyway....
can I "f" with the timing by running tight to go even more radical?
Currently the cam is running about 5 degrees late at the crank and I
attribute this to the 1.42 rocker ratio (actual) versus the "stated" ratio
of 1.5. Hey, Greg wolf (+Ian) of the list commented that "they were all
this hot inside and this hard to get off the line" sos I suspect that the
late timing has given me some torque back by reducing overlap and closing
the intake valve earleir.
Any Einsteins out there? Bob Tullius? Kas himself?
I'm interested in any oppinions but I'd love direct mail lest the list get
into one of those exhause header threads again.
Dave Terrick
"Timing is Everything"
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