Stay away from the pumps from the big 3 suppliers. The slot at the top of the
rotor shaft is cut very sharp and will break. I siezed a motor years ago as a
result of one failing. I have found others with one tab broken off. Another
part of the problem is the shafts are dead soft, whereas the original ones were
hardened somewhat (Rc 50-55). I never fully investigated this to see if they
were just case hardened or if they were thru hardened.
I made my own shafts with generous radiuses and had them heat treated. I am
not set up for any kind of production. Making each is very time consuming
(which I seem to have less and less of). I also replace the pin that the rotor
attaches to the shaft with, with set screws that are locktighted in.
As for compression ratio I have been running 13.6 last year and this year. So
far so good, but last year I did crack a Moldex crank due to a mixture problem
and injested steel imbedded in a piston causing detonation in that cylinder.
With lower compression it may have tolerated the conditions better? Joe B
-- SpiwakD@aol.com wrote:
I need a new oil pump and need to know if an improved or high-quality unit is
available. Also need to know a recommended compression ratio in a TR3 engine
for a combination of good power and reliability.
Dave
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