How much clearance does a main bearing have?
How much clearance does a main bearing have?
As a rule of thumb, main bearing clearance should be targeted between 0.0025- and 0.0020-inch for most street and street/strip engines.
What is the bearing clearance?
Bearing internal clearance (fig. 1) is defined as the total distance through which one bearing ring can be moved relative to the other in the radial direction (radial internal clearance) or in the axial direction (axial internal clearance).
When to tighten bearing clearance on an engine?
Proper alignment of the main bearing caps is critical to running tight clearances. Aluminum blocks expand more than iron blocks, so many engine builders will tighten up the main bearing clearance when building the engine at room temperature, knowing that when the engine attains operating temperature, the clearance will have expanded.
Why do you need a tighter clearance on a shaft?
Tighter clearances are desirable because they cause the curvature of the shaft and bearing to be more closely matched. This results in a broader oil film that spreads the load over more of the bearing surface, thus reducing the pressure within the oil film and on the bearing surface. This will in turn improve bearing life and performance.
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.
What should the bearing clearance be on a crankshaft?
The time-honored formula for determining bearing clearance is .001-inch for every inch of crankshaft main journal or rod journal diameter. “Then if you want to go loose, add .0005,” suggests Lake Speed, Jr., certified lubrication specialist at Driven Racing Oil. “And for tight, take away .0005.
Proper alignment of the main bearing caps is critical to running tight clearances. Aluminum blocks expand more than iron blocks, so many engine builders will tighten up the main bearing clearance when building the engine at room temperature, knowing that when the engine attains operating temperature, the clearance will have expanded.
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.
The time-honored formula for determining bearing clearance is .001-inch for every inch of crankshaft main journal or rod journal diameter. “Then if you want to go loose, add .0005,” suggests Lake Speed, Jr., certified lubrication specialist at Driven Racing Oil. “And for tight, take away .0005.
Tighter clearances are desirable because they cause the curvature of the shaft and bearing to be more closely matched. This results in a broader oil film that spreads the load over more of the bearing surface, thus reducing the pressure within the oil film and on the bearing surface. This will in turn improve bearing life and performance.
