Much to the enthusiast's dismay, many of the 1500 Spits for the US of A market
were equipped with dished pistons that rendered a whopping 7.5 to 1 compression
ratio. This had some benefits in emissions and mileage, but frankly it was not
the hot setup for power and driveability. Casting numbers on the heads will
yield little info as to the true nature of the motor. One bright spot is that
the 1976 1500 motors had a 9 to 1 compression ratio, when Triumph tried a few
tricks to restore some pep into the Spit line. These motors should have serial
numbers in the range of FM40000 thru, uh, FM80000, though there were less than
20,000 1976 Spits cranked out, so seeing a motor number higher than FM60000
might be rare. Actually, what I need to document for purposes of staying legal
in SCCA Street Prepared competition is the overlap of the 9 to 1 motors with
double valve springs in the head. Yet another project.
mjb.
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