List,
Slowly we are getting the MkIII apart. Right now we are working on the 1275
(12CD) engine. This has been rebuilt and has a 0.030 inch overbore. It does
not appear to have had many miles before being taken out of service. The
cylinders look excellent with no ridge, taper and are round. The pistons
also look good for the most part. There is some signs of wear on the wrist
pin side of the pistons, particularly the skirts. Now for the question. The
pistons have four rings and are marked "RA2272-030" on one edge of the top.
On the opposite edge is "Top 0025PK" Does anyone recognize these and if so
do the pistons take a "BMC" ring set or some other manufacture? At least one
supplier specifies these type of different rings.
Update information. At first it looked like we would be able to just put in
new bushings and bearings but after getting the parts cleaned it was apparent
that there was a problem. Throw #4 had a flat spot and had been beating the
rear main to death. The crank was bent 0.005 inch and had already been
reground 0.010 inch under size. The shop was able to straighten the crank
and we will go to a 0.020 inch under grind. Will have to give some thought
as to wether or not to supercharge this engine.
TIA
Bob and Annice
1960 Sprite (Mk IV indiguise)
1966(7) Sprite Mk III (in progress)
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