piston clearance?

is 8 thousths too much piston to wall clearance on a 460

Depends on what the piston is made of, and how it will be used.


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Seems awfall big. Whats the application, bore and piston MFG?

The manufacturer is most important. That determines where it is measured and what it should measure.

Is it where it should be? No, but will it work and be noisy, yes.

I have ran them that loose and more, with a file fit ring to get a good ring seal.

The bore being round is of more concern to me, if it's worn that much and not a screwed up boring job.

Just up to you, on how good of a rebuild you want or need. Probably ain't going to be a 100,000 mile engine.

Hey , just my two cent's worth...............

james00 wrote:is 8 thousths too much piston to wall clearance on a 460

What application, kind of piston material, and exactly where are you taking your measurement?

Paul Kane wrote:

james00 wrote:is 8 thousths too much piston to wall clearance on a 460

What application, kind of piston material, and exactly where are you taking your measurement?

they are trw forged pistons. i am taking measurements about an inch from the bottom of the skirt.this is just a street engine the pistons have been milled to flat tops. 5 of them have 5 thousands clearance and 3 of them are 8 thousands thanks

james00,

If you are going to use them . Put the smallest pistons in #1 and 5 cylinders and the third "small one" in #2. Because of water flow in and out of the block this will be the best location for them. Paul is right , they are loose , but they are not loose enough to cause failure of the piston itself.

james00 wrote:
they are trw forged pistons. i am taking measurements about an inch from the bottom of the skirt.this is just a street engine the pistons have been milled to flat tops. 5 of them have 5 thousands clearance and 3 of them are 8 thousands thanks

In addition to the latest post above and to be prudent, I suggest you first remeasure a cylinder bore(s), and also that you very carefully and consistency measure your piston skirts again and in the exact same location on each piston. You might have 5 good pistons (0.005") and 3 pistons (0.008") with collapsed skirts. This assumes you are measuring used pistons. If they are new then you may disregard this post...but try to take more precise measurements.