Cam Timing

Steve Robertson srobertson at ssimicro.com
Wed Oct 15 09:40:05 PDT 2008


KC,

Thanks for the suggestions. All the measurements I have posted were done
on a spare stock motor that I am using as my practice bench. I started by
measuring the stock cams on this motor and then installed a set of 
aftermarket
cams that someon else had been running. I was just curious to see where they
had set them. I didn't bother to check PTV as this exercise was just about 
learning
how to measure cam timing.

My race motor has the same aftermarket cams in it and strangely enough they 
are
set to the same numbers 109/99.5 I measured them at 40thou lift and got

Intakes
open BTDC 10.5deg
close ABDC 48.5deg

Exhausts
open BBDC 32deg
close ATDC 13deg

I was going to try 106/106 and will try your numbers too. In both cases I 
will definitely
be checking PTV. I was actually glad to see the 99.5 number on my exhausts 
as that
helps explain why my current PTV on the exhuast side is only 60thou. I was 
hoping to
bump up my compression from it's current 12.4 to ~13.5 or 14:1. Hopefully by 
advancing
the exhaust timing 6.5deg I will be able to gain the needed clearance.

Steve



> I found your numbers.... do you now what is your p to v @ 10 after look at
> 103/106 but check p to v !!!!
>
> KC Gager



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