--- James wrote:
> The ONLY was to find out is to put a dial indicator
> on the top of the valve
> and turn the motor over by hand to see what you
> realy have first; then do it
> again with the next ratio installed. Any other way
> is just bulls__t...J.D.
Good point JD and that most defintely bypasses the
fear of knowing exactly what ratio rockers one has,
but not sure I agree that's the best place to
check(that is if the top of the valve is the stem)....
the valve head or tulip is a much better place I
think.
The rocker arm ratio is determined from where the
pushrod contacts the socket of the arm to the point of
contact "between" the rocker arm face and valve stem
tip(right at that point). A different length valve can
throw this off to some extent as the swing starts or
ends earlier in the apex (compared to the centerline
of the rocker arm shaft). I think it would be pretty
tough to get an indicator on that point of the valve
stem if the rocker arm is there, and if we check it on
top of the rocker arm the ratio is not going to be
exact, as it is not trully a vertical push at that
point(the rocker arm swings an arc instead of
traveling vertical).
I have tested some RA ratios(mainly to see how much my
refacing has effected them) by checking lift at the
valve tulip in the chamber(head off, rockers installed
and simulating a pushrod via an indicator using true
cam lift) before and after refacing. This lets true RA
ratio be figured by dividing valve lift by true cam
lift(this takes into consideration everything from the
lifter to the valve stem length). As I mentioned I've
also found plenty of cams offbase from what the
advertiser/manufacturer states so I always go by what
I measure on the cam itself.
When trying to figure what's needed for a certain
application most don't have the supply of cams to
check it out the way you mention to get what they
want, so by all rights cam lift x RA ratio is an
accepted way to check when buying a cam or in this
case for Scott to see where he'll be with an alternate
RA ratio.
I do like your way if the vehicle is assembled and you
are trying to get some kind of initial lift number,
but if bulls__t means not being exact, then I guess
the motor would need torn down IMO.
Not being combative here JD.. just letting everyone
know where I'm at so i can be told what I'm doing is
bulls__t if so(i always like learning better easier
ways).
Todd-
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