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38 coupe · 05-13-2024, 05:58 PM

I used four balls of tin foil stuck to each piston (center, far left, far right, bottom, didn't worry about the top with the clearance in the factory head) with a dab of grease, bolted the heads down using four head bolts, and spun the crank over a couple times. Pulled the heads and measured the tin foil. The tin foil has a bit of spring, but you can tell well enough what your clearances are. The modeling clay may be a little bit more precise, but I find tin foil easier to grab in short notice.
My friend got a bit enthusiastic on surfacing the heads on this 1950 Mercury engine (.035 clearance) and ended up using a flap disk to carefully add clearance over a couple pistons. This was also not a super precise method, but clearance was verified by a second round of foil balls and dang that engine runs well.

05-13-2024, 05:58 PM	#241
38 coupe Senior Member Join Date: May 2010 Location: South Texas Posts: 1,717	Re: 276 stroker from 35 years of parts I used four balls of tin foil stuck to each piston (center, far left, far right, bottom, didn't worry about the top with the clearance in the factory head) with a dab of grease, bolted the heads down using four head bolts, and spun the crank over a couple times. Pulled the heads and measured the tin foil. The tin foil has a bit of spring, but you can tell well enough what your clearances are. The modeling clay may be a little bit more precise, but I find tin foil easier to grab in short notice. My friend got a bit enthusiastic on surfacing the heads on this 1950 Mercury engine (.035 clearance) and ended up using a flap disk to carefully add clearance over a couple pistons. This was also not a super precise method, but clearance was verified by a second round of foil balls and dang that engine runs well.