New Pistons

[cwestra]

I had my block bored .030 over and supplied my machine shop with the pistons I'm using so they could size the bores to them.  The pistons are KB from Mancini.  When I got the block and pistons back I noticed no indication on which pistons went with which cylinders.  When I asked them about it they told me that the pistons measured consistent and it did not matter which cylinder they went into.  Is this common or not?

[Moparal]

On a non performance engine it wouldnt matter if they were close enough say with in a thou or .0015  but if you have valve reliefs and install them wrong, the piston could hit the valve. Since the piston lines up with the valves. Did they use a tq hone plate?

[cwestra]

On a non performance engine it wouldnt matter if they were close enough say with in a thou or .0015  but if you have valve reliefs and install them wrong, the piston could hit the valve. Since the piston lines up with the valves. Did they use a tq hone plate?

So, in general, for a steet machine it is not necessary to size a bore to the specific piston, correct?  And yes, they did use a deck plate for honing.  Thanks for the reply.

[Moparal]

The hone to size bore is the final.  File fitting rings is important. But for the most part,  0.001 wil hardly be noticeable. My pistons I just installed were withing 1 and the bore was right on.  Just dont fit the rings to tight to the bore or you will have a failure down the line.

[cwestra]

The hone to size bore is the final.  File fitting rings is important. But for the most part,  0.001 wil hardly be noticeable. My pistons I just installed were withing 1 and the bore was right on.  Just dont fit the rings to tight to the bore or you will have a failure down the line.

Thanks.  The rings have about .011 gap now.  Is that too tight?

[Moparal]

Yes that is way to tight. The pistons will swell up and cause the rings to expand into the cylinder causing major problems.  I think the formula for the top ring is like bore x .005 for gas engines no nitros or blower

my top ring was 4.375 times .005 =  .022  or .021875  I will look in the shop today for the correct useable formula but this is close.

[Moparal]

Yes that is way to tight. The pistons will swell up and cause the rings to expand into the cylinder causing major problems.  I think the formula for the top ring is like bore x .005 for gas engines no nitros or blower

my top ring was 4.375 times .005 =  .022  or .021875  I will look in the shop today for the correct useable formula but this is close.

top =  bore x's .0045   2nd bore x's .005    and oil rings minimum  .015

[cwestra]

top =  bore x's .0045   2nd bore x's .005    and oil rings minimum  .015

Thanks a lot, Moparal.  You've been a big help.