[DeTomaso] FW: Rocker Stud angle question

[JDeRyke at aol.com]

In a message dated 1/2/08 1:40:52 PM, doug at silicondesigns.com writes:

> My goal is to machine the rocker stud bosses for 7/16" non-positive stop 
> studs.  My reasoning is that I have free access to a milling machine and I like 
> playing with this kind of stuff.  The Manley
> cutter was $70 and their 42277-16 stud set is only $50.
> 
Is that the cutter that pilots on the existing tapped hole in the bosses? 
Boss rocker studs are at a compound angle to the horizontal- also known at the 
time as poly-angle valves. They are at 4 degrees 15 minutes of angle in one 
plane and 9 degrees 30 minutes of angle in the second direction. Photos of this 
are more confusing than informative. All the mechinists I know that have done 
this mod dial-indicate the flat area between the 'ears' on each pedestal and cut 
the pedestal down accordingly. This is extremely time-consuming to do 
correctly with lots of opportuninty to do it wrong, which is why most use an Isky 
pedestal cutter- much faster for often more accurate results. And extreme 
accuracy is not needed unless you use full roller rocker arms; there's enough slop in 
stock rocker pivots to absorb some mistakes- especially if you use big-block 
Chev ball-pivot rockers.
Note also that stock Boss intake & exhaust valves have different stem lengths 
which will tip some rockers at more angle than others, just to throw another 
number into the mix. Good luck- J DeRyke


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