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Old 03-03-2008, 07:55 AM   #15
JoeT
Scooby Specialist
 
Member#: 3956
Join Date: Feb 2001
Location: Toronto, Ontario, Canada
Vehicle:
2000 Turbo Legacy GT
Titanium

Default

Wiseco supplies recommended clearances for their pistons, and a knowlegable machine shop would also know how to properly size the bores to match pistons.

When buying a used block, it's always a good idea to check the bore size to make sure that the clearances are within the acceptable range for the intended pistons. Normally when using "used" block, it's a good idea to get a 1 over piston (oversized) then have the block machined to match each piston. While they're at it, the machine shop can also "gap" the rings for you.

From there it's a matter of checking the other clearances like, big end (crank bearing clearance), connecting rod bearing clearance, etc. etc. using a plastiguage. It's also good practice to have the crank surfaces re-polished while it's out.

Things to note: If your bearing clearances are too wide, your oil pressure will be low.

In your cast, my guess is that you've got excessive clearance between "stock sized" wiseco pistons in an enlarged bore from a used EJ257.

I used to use Arias Pistons and Pauter Rods on one of my engines, that was noisy, since the Arias recommended tollerances were wide. I'm currently using Wiseco Pistons on Eagle Rods, and it's a quiet combination. When warm it's almost as quiet as OEM, when cold there is a bit of slap but not much.
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