What is used to measure main bearing clearance?
dial bore gage
For these reasons, bearing clearances are specified as “vertical clearance” and must be measured at 90 degrees to the split line. The best method of measurement is with a dial bore gage that measures the bearing inside iameter when the bearings are installed at the specified torque without the shaft in place.
What are the bearing clearances for an engine?
Most of these engines are running rod and main bearing clearances of .001? or less, and they are doing it with low viscosity racing oils such as 0W5, 0W30 and 0W50. These racing oils are as thin as water and are highly friction modified.
How is rod side clearance used in engines?
This approach minimizes rod side movement with tight clearance between the small end of the connecting rod and the piston pin bosses. This allows the engine builder to use narrower connecting rods and bearings.
What should the clearance be on a crankshaft rod?
Again, transfer the measurement from the crankshaft rod journal to the dial bore gauge and zero the dial indicator. Then check the clearance inside the rod bearing shell, measuring 90 degrees from the parting line.
Where are the main and rod bearings located in an engine?
Finally, the crankshaft is attached to the engine block. Rod bearings are inserted between the rod and the crankshaft. Main bearings are present between the crankshaft and the block. The gas-air mixture in each cylinder of an engine explodes and pushes the pistons downwards.
Are there any bearing clearances for racing engines?
Engine connecting rod and main bearing clearances have tightened in recent years for many racing applications, but there are caveats to this trend that engine builders need to acknowledge before bending traditional guidelines, especially when adapting those practices to street engines. “It’s easy to whip these numbers out.
What is the standard bearing clearance for plastigage?
If you do use Plastigage, check across the entire bearing to ensure there isn’t a tapered journal. “If it’s too tight, everybody knows. Too loose, and you know,” quotes Himley. The time-honored formula for determining bearing clearance is .001-inch for every inch of crankshaft main journal or rod journal diameter.
Again, transfer the measurement from the crankshaft rod journal to the dial bore gauge and zero the dial indicator. Then check the clearance inside the rod bearing shell, measuring 90 degrees from the parting line.
What should the bearing clearance be on a small block Chevy?
So for a 2.45-inch small-block main journal, the bearing clearance would be 0.0024-inch. For a smaller 2.100-inch rod journal, the accepted clearance would be 0.0021-inch. Factory acceptable tolerances on a stock small-block Chevy are much wider than this. Start by measuring the crankshaft for rod and main journal diameters.