Main studs - Align boring really necessary?
The issue when switching from main bolts to main studs is the clamping force is applied differently. I know it sounds dumb, but a bolt holds the block to the girdle and a stud holds the girlde to the block. This force acting in an opposite direction can sometimes have a tendency to distort the block. That is why the alignment of the mains must be checked when you switch. I would say 9 out of 10 cars are unaffected but every now and then it can be thrown off a small amount.
I would be very surprised to see any variation in alignment due to main studs, especially with the Evo's main girdle. Definitely plasti-gage the journals, though. If the clearance is different on one end of the journal, something's amiss.
I already bought ACL race bearings and a new crank. Plastigage is on the way, too.
I usually just lay a long piece across the journal. You can see taper in the clearance that way. I'm neurotic about bearing clearances. Also, never, under any circumstances assume your clearances are good and just bolt together an engine. The chances that something will go wrong is not worth the money saved on plastigage.
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Torque the studs down without the crank or bearings and measure the vertical and horizontal bore of the journal. Should be the same. If the studs did distort the block, then the vertical will be shorter than the horizontal.
and if u have ur build motor , using arp main studs , and u lift ur car to replace the arp main studs u have already with new ones ??? beacuse they were overtorqued the first time they were put in ..
I'll begin the rebuild this week. I'm still not sure if i'll stick with bolts or switch over main studs.
If the block do distort, then I'll have to align bore it and use oversize main bearings. Not very fond of that.


