Quote:
Originally Posted by Dave in MN
Synchro,
I made a series of tests on an engine I was building for myself on my dyno some years back related to the required oil clearance for the insert bearings I use. I found I needed to increase the oil clearance for the rear main to between .002" to .0022". Any tighter and I could experience a failure (lock up) when the engine was heavily loaded. The manufacturer suggests .00175" and that will work for the front and center bearings, I prefer .002".
I tried increasing the oil groove at the parting line of the inserts approaching .25" from the rear of the bearing but it also failed. The only thing that worked was more oil clearance.
Hope you solve your issue.
Good Day!
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Thanks, Dave. This motor has done about 40,000 miles, mostly while working hard towing a camper that weighs about the same as the car at 50mph all day long. The journals are slightly worn so I hope that will give a little more clearance for now.
I'm only mildly surprised that widening the gap between the inserts didn't work. I think a spiral groove would work much better because the rotation of the crank shaft would help the oil along it