Has anyone measured the dome cc's of the OLD Jhans cast pistons? I measured using the .500 down the cyl method, and got 9 cc's. But that didn't seem like enough. So used modeling clay, and pushed the piston top into it. Then measured that, and got 15 cc's. That's a pretty big discrepency. I have a pretty bad cold, and my shop is pretty darn chilly, so not going out there for a few days, to do all this again.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Never done any Jahn's, but have done many, many other domed pistons. You only need to install the piston far enough down in the bore for the tallest part of the dome to be about .015" or .020" below the deck surface. And then calculate for that depth, it takes less solvent also most of the time. Very important to have the piston square in the bore with the flat deck area of the piston. If you have taken the piston in and out of the block, this can account for the discrepancy if you didn't resquare it as accurately as the time before. Also, on pistons that have a dome and valve reliefs, you often end up with a lower effective dome volume than you think you will because the reliefs take away almost as much volume as the dome adds to the equation.
Good luck.

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There's no such thing as too much cam....only not enough engine!

I have done this many times in the distant past. I know I screwed up somewhere, and need to redo it. Just too cold to work out in the shop, right now. Just wondering if anyone of the old timers, remember about the Jahns pistons.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225