I received my crankshaft from the machine shop, and my new bearings from BPNW.
I seem to be having a clearance problem between the connecting rod bearings and
the crankshaft. The more rods I tighten down, the more increasingly difficult
it becomes to turn the crankshaft (the head is still removed). If all 4 are
torqued down to spec, I cannot turn the crankshaft at all by hand. If all 4
rods are tightend to only about 15 lbs each, the crank turns fairly easily.
I've tried torqueing the rods in different sequences, and the result is still
the same. I also made sure the the caps went back onto the same rod from which
they came.
The machine shop turned the crankshaft main and rod journals to the .010 spec
listed in the manual. I purchased .010 bearings to match. The clearance of the
main bearings seem to be fine, as the crank will rotate with little effort
without the rods attached, and doesn't seem to be loose. I checked the
crankshaft connecting rod journals with a micrometer, and the reading is right
on at the large end of the spec. listed in the manual. I checked the difference
between the thickness of an old rod bearing and a new rod bearing. This
difference is .007". This would mean that the total difference accross the
diameter of the big end of the rod with the bearings in place is .014" (.010
for the size on the new ones and .004" for wear on the old ones, if I've done
the math correctly). This is a little puzzling as the old bearings showed
little sign of wear (I think this engine had been rebuilt shortly before it was
retired 14 years ago).
Tonight, I plan to check the clearance using plasti-gauge, and I'll mic
everything again just to make sure. What have I missed? Should the crankshaft
be so difficult to turn? Is there something else I should be looking for? Has
anyone else experienced a similar problem?
For those of you who have something other than a Haynes TR2-4A repair manual,
what does it show for the std. connecting rod journal diameter?
Jeff Williamson
'58 TR3A
'60 TR3A
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