Hey Guys,
The 250's engine is in pieces as part of the ongoing rebuild. I am sort of
at a decision point on the cylinder head. Current head original to the
motor is 3.420" and the block is bored .030 over. They are telling me that
this
is giving a compression ratio of 9.5 to 1. We will need to bore the original
block to .040 which would raise the compression to 9.7 to 1.
My goal with this Triumph is to build a stock motor. Previously the 250 was
pretty powerful from 3,000 revs to the redline. It was fun and I tore it up
pretty good. It was also impossible to tune for an acceptable idle. With the
stock goal in mind, I have been given the following options. An uncut 69
early TR6 head is available for rebuild which is claimed to return the
compression to the desired stock 8.5 to 1. Actually I believe stock may have
been 8.6
to 1. Those heads would be the same correct? This claim seems to omit the
oversize bore as a function of compression? Confused about that. Also what if
the block has been decked? Should I inquire?
Also I have asked for a stock grind on the camshaft. Would that profile
effect compression? In addition I have a complete TR250 motor from another car
that has never been touched but numbers don't match my car. Too many choices
and I don't want to regret what get's done so I would appreciate the
advantage of having the wisdom of the List.
Thanks in Advance,
Darrell
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