Someone already noted that there is a difference in these
engines which requires changing the front plate on the engine
in order to accomodate the different location of the
motor mounts in the 3 vs the 4.
Another difference in 3 vs 4 engines is that the later
TR4 engine did not have any crankcase ventilation
tube near the rear of the engine on the driver's side.
The hole was still there, but it was blanked off with
a steel plug which could be removed to actually
install the crankcase vent tube if you wanted to when
installing the engine in a TR-3 or early 4.
Someone else mentioned the larger diameter pistons, but
stated they were 87mm. The correct diameter
is 86mm. The 87mm pistons/sleeves are the .040 larger
pistons allowed by SCCA competition rules (I don't
know what the rules are today, but that was what was
allowed in the old Production classes in the 1970's.
FYI, correct diameter of the TR-3 engine was 83mm EXCEPT most
of the TR-3B engines were the larger 86mm size.
If anyone is concerned about originality, I can tell you that
the Vintage Triumph Register
judging of cars does not include engine serial
numbers (and I hope we never get that silly). I am not
sure how detailed other clubs (eg. TRA) might be on
the engine serial number vs the vehicle type.
Cheers,
Cheers,
Bill Sohl Budd Lake, NJ billsohl@planet.net
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Visit the Mount Olive Township Republican Party Home page at:
http://www.cns-nj.com/mtolive
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