Re: Spider cylinder head height?

[AlfaNeely@domain.elided]

In a message dated 11/20/2002 10:38:19 AM Central Standard Time, 
JeffreyOlson@domain.elided writes:



> Is the minimum measurement 4.39 inches (111.5mm) a limitation because of 
> compression ratio or valve interference?
> 
> That's what am now wondering after you mentioned the competition 
> measurement.
> 
> Thanks!
> 
> Jeff
> 



       I thought it was due to concerns that the head would warp in use.  The 
thinner the head, the less stable it is.  That is why you can cut it so much 
more for competition.  In racing things are closer to the edge and are 
expected to blow up occasionally.  However, I would not hesitate to go to 
0.075 inch total cut or down to 110 mm.
       I once had a 1750.  When I built it, I told the guy who ground the 
valves to give it a "clean up" cut of 0.020.  Turns out it had been cut 
before and was then cut about 0.075 total.  I had to run a copper head gasket 
to get it to run on premium gas.  
       That is how I learned about Alfa's specified head thickness.  And I 
now measure the head before having it cut!  That was also the first Alfa 
engine I ever built.

       It is always good to measure valve to piston clearance.  Put modeling 
clay on the piston tops, assemble the engine, time the cams, gently turn it 
over a couple of turns, take the head back off and measure the clearances.


Ciao,
Russ Neely
Oklahoma City
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