Veifying Main Bearing Clearance - Checked Mains - CHP Step By Step

Verifying Main Bearing Clearance

Sean Haggai Nov 9, 2010 0 Comment(s)
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Setting the tone for your build begins with starting out on the right track. Overlooking steps and taking shortcuts are no way to piece together an engine; regardless if it's for the street or strip. While it may seem like parts fly off shelves and magically compose themselves into engines, they don't. There are codes of conduct that must be followed like preplanning and measuring essential dimensions such as the crank journals, main bearing tolerances, and crankshaft endplay. To ensure the bearings have adequate clearance to maintain oil pressure, this crucial process can't be passed up. In either situation, it's a recipe for disaster if it's neglected. By simply checking these items ahead of time, you can prevent a full-blown meltdown, not to mention some serious pocket digging and downtime should things go bad.

chp_01_o Veifying_main_bearing_clearance Gauge 2/11

To do the job you'll need some tools of the trade, but the good news is it only takes a little know-how to get the job done. To help clarify why checking the clearances is important, a bearing with too little clearance can build heat quickly under extreme loads of the crankshaft and eventually burn the bearings out. On the other hand, too much clearance between the bearings and crank journals will not create enough oil pressure which, in turn, will starve the engine of lubrication.

To showcase our efforts, we jumped on board with Quarter Mile Performance in Chatsworth, California, where Michael Consolo was piecing together one of his personal mills, a 410ci race only small-block that's destined for the strip. While this isn't a typical street motor designed for stop-and-go traffic, the methods shown here are applicable for all combinations. If you lack the tools to get this particular job done, your local engine shop should be able to offer these services; that means do it once and do it right.

Quick Notes
What We Did
Checked the main bearing clearance on a 410ci small-block

Bottom Line
Basic engine building fundamentals can go a long way

How Long It Took
Two hours


Quarter Mile Performance




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