Rebuild questions SBC
02-09-2010, 10:01 AM
#1
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Rebuild questions SBC I bought a SBC 4 bolt 010 block with alot of nice machining done to it. Problem is, there is some very minor surface corrosion in the bores from where the PO didn't grease it up before storage. I was planning to use some PB Blaster and a green scotch brite pad to clean them up, I just don't want to mess up the nice cross-hatch. Think I'll be okay?
Also, along with this engine I got a set of forged pistons that came out of it. The block and pistons are .060 over and it looks to be rebuilt twice already. The block was sent back to the machine shop by the PO (without the pistons) for a torque plate hone so it could be re-ringed. I've always sent the pistons with the block for boring/honing so the machinist could get them perfect. My question is, wouldn't the piston-to-wall clearance be too much now since the cylinders were honed for these pistons on the last rebuild? I would really like to use these pistons and save myself $500 bux lol.
Also, along with this engine I got a set of forged pistons that came out of it. The block and pistons are .060 over and it looks to be rebuilt twice already. The block was sent back to the machine shop by the PO (without the pistons) for a torque plate hone so it could be re-ringed. I've always sent the pistons with the block for boring/honing so the machinist could get them perfect. My question is, wouldn't the piston-to-wall clearance be too much now since the cylinders were honed for these pistons on the last rebuild? I would really like to use these pistons and save myself $500 bux lol.
02-09-2010, 11:21 AM
#4
I think the clearance will be fine, i have done some crazy **** with stock pistons so those forged piece should be fine if it was just honed. As fr the rust, i would have to see how bad it is, i would use some fine steel wool if it is just really minor.
02-09-2010, 11:36 AM
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Well after reading some more it seems that a slightly looser clearance would be ideal since I'm gonna be running a turbo and forged pistons. Someone step in and slap me if I'm wrong, but if it comes out to be .005-.006" clearance I'm gonna roll with that.
02-09-2010, 01:37 PM
#6
Go with the piston manufacturer’s recommendation. If it’s a 2618 Aluminum, the piston manufacturer typically will call out for a larger piston to wall clearance when compared to a 4032 or other high silicone content piston. 0.005-0.006" clearance sounds very acceptable for a 2618 piston in a mild to mid hp application. I run a little looser than that on my 1350 hp turbo motor with no issues related to excessive piston rock. Even some of the piston manufacturers have completely different recommended clearances when using the same alloy material on similar pistons.
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02-10-2010, 09:54 PM
#9
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x2 one time i pulled apart a very high mile 350. there was .027" cylinder wear
weird thing is there was no audible piston slap. i would say the OP will be fine.
