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Mike Gray · 03-31-2025, 11:16 PM

Negative vs. Positive Clearance:
Negative clearance means the piston protrudes slightly from the deck surface, while positive clearance means the piston sits a bit inside the cylinder bore.

The .0005 on the chart appears to be a positive number so the piston should be below the deck. I assume if it’s assembled .0005 above a .048 gasket gets you back to correct deck clearance.

03-31-2025, 11:16 PM	#4
Mike Gray Senior Member Join Date: Oct 2006 Posts: 615 Likes: 308 Liked 685 Times in 196 Posts	Re: 139 hp 302 ford help Negative vs. Positive Clearance: Negative clearance means the piston protrudes slightly from the deck surface, while positive clearance means the piston sits a bit inside the cylinder bore. The .0005 on the chart appears to be a positive number so the piston should be below the deck. I assume if it’s assembled .0005 above a .048 gasket gets you back to correct deck clearance. __________________ Mike 7570 A/SA Last edited by Mike Gray; 03-31-2025 at 11:29 PM.