> Is there an advantage to using a TR4 head rather than a 3 head on a TR3
> block? Would there be any other modifications necessary other than just
> switching heads?
After the switch to the "high port design" (very late TR2 or early TR3) the
heads are
basically interchangeable (although they have different part numbers). The
exhaust valve
stems are 3/8 on the TR3 - early TR4, afterwards they became 5/16. (I would
check with
some other TR folks, though, I know there no problem fitting the earlier head
to the
later engine, and the valves can be converted using "conversion" valve guides.)
>
> Related question: I also have the rocker arm cover for the TR4 head.
> Would it be better to use that cover and vent the crankcase emissions
> through it to the intake (a la TR4) or keep the TR3's vent on the side of
> the block?
Unless you want to fit the entire PCV system from a TR4 and block off the
crankcase tube
completely, I'd leave the vent. You could use the TR4 cover and simply put a
little
filter on it....
Good luck.
Christopher M.Lillja
Marketing Associate
Princeton University Press
Tel:609 258 4900
Fax:609 258 6305
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