Tom,
Hmmm. Lemme see.
Compression pressure (all things being equal) will go UP when the head is
shaved (or any other method of increasing compression ratio is effected)
high compression pistons for example.
How you can tell if the head has been shaved is to CC the combustion
chambers.
This requires removing the head.
With the head laying on the workbench and the valves and spark plugs in it
pour a measured amount of solvent into one of the combustion chambers. This
measured amount will either match with the factory displacement of the
chamber or it won't. If the amount is smaller than the factory amount then
the head has been milled.
Understand that it is normal procedure to mill a head a SMALL amount, .003"
or so in the course of doing an engine overhaul or when doing a valve job.
This makes the head FLAT where it mates to the block and makes for a better
seal to the head gasket.
I only know of ONE way to determine if your engine has been modified for
SURE and that is to disassemble it.
Hope this helps,
Jim
tom popkes wrote:
> Hi Listers
>
> I suspect that the head of my spitfire engine may have been
> shaved,effectively raising the compression ratio.My question is: can the
> compression ratio be calculated / measured without taking the head off ?
> Would an increase in compression ratio raise the cylinder pressures ?
>
> ++++++++++++++++++++++++++++++++++++++++++++
> Tom Popkes, tpopkes@cgocable.net
> Two Spitfires;one red, one blue and one yellow VW Bug
> Boot and Bonnet , VTR and Toronto Triumph Club
> ++++++++++++++++++++++++++++++++++++++++++++
--
Rawchester, Neu Yawk
Sptifire MkII "HardWay" FC68436L Red, what else?
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