main bearing clearance ls1

**crossbredfoxbody** · 04-04-2010, 04:20 PM

I'm building my first ls engine and I installed the crank and checked the main bearing clearance with plastic-gauge and I come up with .0015 on all but the 2nd journal It was .002 any help would be appreciated. Do they make bigger bearings like by 1 thousandth? I feel like I need more clearance this is a drag race only ls1.

**importhater81** · 04-04-2010, 04:58 PM

.0008-.0025" is the service specs per G.M.I wouldn't sweat a .0005" difference on one journal.

**importhater81** · 04-04-2010, 05:05 PM

They do make bearings by the .001' oversized,but as you stated you are building a drag only motor so I would think that the clearences you have now are good...Using that one oversized bearing on that #2 main will probably make that journal to tight.I'd stick with what you have.

**crossbredfoxbody** · 04-04-2010, 05:16 PM

.00075 x 2.559=.00191925
3/4 x Crank journal=
Some people say use .010 x 2.559 Which is correct?

**crossbredfoxbody** · 04-04-2010, 05:30 PM

High Performance engines on the other hand, typically employ
greater bearing clearances for a number of reasons. Their higher
operating speeds result in considerably higher oil temperatures and
an accompanying loss in oil viscosity due to fluid film friction that
increases with shaft speed. Increased clearance provides less
sensitivity to shaft, block, and connecting rod deflections and the
resulting misalignments that result from the higher levels of loading in
these engines. Use of synthetic oils with their better flow properties
can help to reduce fluid film friction.