Mitch---Since you asked for more than your original request, I'll answer
them last.
First, you say you have the head from the 1973, and it's unmodified. To
get to a 9.5:1 compression ratio it's necessary to mill .114 from the
head. If you want the formula, it goes like this:
8.5 (-) 6.75 divided by 8.5 X 6.75 X 3.74 =
1.75 divided by 57.4 X 3.74 = .114
.114 needs to be taken from the head.
The head should now be 3.425 thick.
****************
I believe the dual valve springs is a little easier on the valve train
than a comparable single spring. The inner spring provides some safety
should the outer spring break. Either will work if the rate is right.
A 12 lb. (aluminum) flywheel is a little light for the street AND a
performance cam. You won't notice this (lighter weight) between shifts,
but possibly at idle.
Shorter pushrods is the correct way to go (per Kastner) when a head is
milled any fair amount. It could be argued that if you have enough ball
stud adjustment left at the rockers to set the valve lash, it won't
upset the geometry here that much to use the stock rod lengths.
Sounds like you're trying to do this right. Good luck...
Dick Taylor
'73
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