forged piston cylinder wall clearance on rebuild?

markduanetaylor · 03-08-2001, 10:51 AM

I am doing a rebuild on a boss 302 engine. The pistons are forged. What is the desired wall clearance between piston and cylinder wall. How much clearance would be unacceptable to rebuild without doing a bore? Thanks in advance. Mark Taylor

Rev · 03-08-2001, 02:38 PM

If you're gonna do a rebuild, don't go to the trouble without doing complete machine work. Make sure the bores are round and the texture is correct. I'd recommend getting a machine shop that uses torque plates and an automatic honing machine for the final bore finish. Get the specs for the final piston skirt clearances from the piston manufacturer. If you're serious here, do a more or less blue print. Get the block decked, align honed and everything perfectly square. Make sure the heads are in good shape with a 3 angle valve job and pocket ported. The crank should be turned and new cam bearings and freeze plugs. You'll need a good machine shop for most of this. I wouldn't cut corners if at all possible. It would only come back to bite you. My $.02.

Rev

------------------
'66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph
1/4 mi.

03-08-2001, 10:51 AM	#1
markduanetaylor Registered Member Join Date: Apr 2000 Location: Booneville MS 38829 Posts: 28	forged piston cylinder wall clearance on rebuild? I am doing a rebuild on a boss 302 engine. The pistons are forged. What is the desired wall clearance between piston and cylinder wall. How much clearance would be unacceptable to rebuild without doing a bore? Thanks in advance. Mark Taylor

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03-08-2001, 02:38 PM	#2
Rev Registered Member Join Date: Nov 1998 Location: Houston, Tx. Posts: 3,887	If you're gonna do a rebuild, don't go to the trouble without doing complete machine work. Make sure the bores are round and the texture is correct. I'd recommend getting a machine shop that uses torque plates and an automatic honing machine for the final bore finish. Get the specs for the final piston skirt clearances from the piston manufacturer. If you're serious here, do a more or less blue print. Get the block decked, align honed and everything perfectly square. Make sure the heads are in good shape with a 3 angle valve job and pocket ported. The crank should be turned and new cam bearings and freeze plugs. You'll need a good machine shop for most of this. I wouldn't cut corners if at all possible. It would only come back to bite you. My $.02. Rev ------------------ '66 Coupe, 306, 300 HP, C-4, 13.97 e.t., 100.3 mph 1/4 mi.