What would an average bearing oil clearance be?
The traditional bearing clearance standard for street and most performance applications has been 0.001-inch of clearance for every one inch of crank journal diameter. So a typical small-block Chevy 2.200-inch rod journal would call for a bearing clearance of 0.0022-inch.
How is main bearing clearance calculated?
By now, you will have the specs on the crankshaft mains and rods, the journals for both, and the specs on the bearings. Subtract the crank spec from the journal spec, and then subtract the bearing spec from that result. This figure is the clearance.
What would happen if main bearing clearance is too loose?
Too little clearance and you’ll have trouble keeping your oil temperatures in check, and a spun bearing is much more likely. On the other hand, if the tolerance is too loose you hemorrhage oil out from around all the bearings.
How do you adjust main bearing clearance?
The commonly accepted rule that most crankshaft manufacturers prefer for street and performance engines is 0.0010-inch for every 1-inch of journal diameter. So for a 2.45-inch small-block main journal, the bearing clearance would be 0.0024-inch.
How do main bearings affect oil pressure?
Engine bearings are curved pieces of metal that more resemble a potato peal than the bearings on your bicycle wheels. If the clearance between the bearings and the shaft is too great, pressurized oil leaks beyond the sides of the bearings, allowing the pressure to drop in those drilled passages.
Do I have to use Plastigage?
It would be prudent to use plastigauge on the main and connecting rod bearings. It’s not super accurate, but could prevent a major clearance error.
How much is C3 clearance?
The same bearing with a C3 fit will have about one thousandth of an inch clearance. This value is less than the diameter of a human hair! Internal clearances are also relative to the bearing’s bore size (the amount of radial play will increase as the bore size increases).