je 10.5 compression pistons

[carrerarsr65]

i have a stock 3.0sc case never been machined just received my new je hi compression pistons i was wondering what other guys are running for base gaskets for a safe piston clearence, it seems that these pistons are pretty popular ,so i was wondering what would be safe .25 or maybe .50 any help would be great

[IXjamesXI]

All depends on how "tall" your cylinders are (deck height) and how "long" your rods happen to be.. Right? Convention says you want about 1mm between the edge of your piston and your deck. Assemble sans base gasket, measure your clearance, and then select the right base gasket. Others here know more and will inform you.. Plenty of info to research here too

[Walt Fricke]

Right - you can't do this with any confidence without measuring things. I'd start with the normal base gasket, and see where that leaves you. I use clay and solder, because I don't trust my calipers for measuring a short distance on a curved surface. Some pros look at it the other way around and rely on their caliper measurements.

Clay will help check valve clearances, too.

[lindy 911]

As said, a dry run assembly is needed. I'd use a stock base gasket and assemble the piston to rod, then cylinder, then head. A 2" piece of solder on either side of the piston crown and then turn the crank a few time to smash the solder with the piston against the head. Pull the head and measure the thickness of the solder. That's your answer. I used stock base gasket with Mahle nickies and '78 SC head and was fine.

[Walt Fricke]

Right - for piston to head clearance a dry run with just one cylinder (maybe leave off the rings, too?) is easy as can be.

Valve clearance is trickier, as you need the cam. But you can still do it with just one piston (if you decide checking one is checking all), and two cylinders and one set of rockers (whose shafts don't have to be tightened in place). If a guy thought ahead, he'd do this while assembling the valve springs in his heads, and use checking springs (any old not very stiff spring) to make setting timing easier.