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Bored&Stroked · 08-12-2018, 02:59 PM

The other thing you need to think about if you're running a tighter squish than about .035 to .040 is piston to cylinder wall clearance and piston rock. When running larger clearances (with forged pistons for example), you will have more potential piston rock (especially when cold). This means that the static dimension of .040 might get to .020 on the 'high side" if the piston rocks (just for discussion sake). There is always a certain amount of rock - though it will vary by piston material, bore clearances, application, ring packs, etc..

To see for yourself, when building a new engine push on the sides of the pistons and put a dial indicator on the edge - you'll get an idea as to how much rock is possible with just hand force.

08-12-2018, 02:59 PM	#34
Bored&Stroked Senior Member Join Date: Jan 2011 Location: Central Ohio Posts: 5,064	Re: Piston to head clearancing The other thing you need to think about if you're running a tighter squish than about .035 to .040 is piston to cylinder wall clearance and piston rock. When running larger clearances (with forged pistons for example), you will have more potential piston rock (especially when cold). This means that the static dimension of .040 might get to .020 on the 'high side" if the piston rocks (just for discussion sake). There is always a certain amount of rock - though it will vary by piston material, bore clearances, application, ring packs, etc.. To see for yourself, when building a new engine push on the sides of the pistons and put a dial indicator on the edge - you'll get an idea as to how much rock is possible with just hand force.