piston clearance issues
piston clearance issues
Road Warrior
Joined: Jul 2007
Posts: 1,898
Likes: 67
From: Saint Amant, Acadiana
With watercooled engines I used to rebuild and modify the rule of thumb was simple, put piston into cylinder and let it drop (no rings). It was supposed to fall slowly. No fall - too tight, drops like a stone - too loose.
Stellar HDF Member
Joined: Aug 2009
Posts: 3,212
Likes: 212
I know in the car world, .002 to .004 is pretty standard for naturally aspirated builds with forged pistons and a little more clearance for boosted engines. You can get about .0015 to .002 for cast pistons.
Your best bet would be to call up Wiseco and talk to someone. Under their FAQ's they had this to say:
"The factors that affect this are cylinder wall thickness, whether the block is filled, the overall compression height of the piston, piston material and thickness, and whether a marine engine is to see fresh-water cooling. Most small blocks get .004 piston to wall clearance and most big blocks get .005 due to the use of our 2618 high-strength alloy. For heavy blower and nitrous applications, Wiseco recommends adding .001 to the standard clearance. Special note: Clearance numbers are obtained from measuring the largest diameter of the piston, typically at the bottom of the skirt. All measurements should be taken 90 degrees from the pin centerline."
Your best bet would be to call up Wiseco and talk to someone. Under their FAQ's they had this to say:
"The factors that affect this are cylinder wall thickness, whether the block is filled, the overall compression height of the piston, piston material and thickness, and whether a marine engine is to see fresh-water cooling. Most small blocks get .004 piston to wall clearance and most big blocks get .005 due to the use of our 2618 high-strength alloy. For heavy blower and nitrous applications, Wiseco recommends adding .001 to the standard clearance. Special note: Clearance numbers are obtained from measuring the largest diameter of the piston, typically at the bottom of the skirt. All measurements should be taken 90 degrees from the pin centerline."
Last edited by Scuba10jdl; Dec 2, 2011 at 11:30 AM.
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