Hey guys,

I am about to do my build and I have new Speed Pro Pistons in Standard size but I was told by the machine shop my cylinders are over .2500 to .3000 over and would need to be bored to 30. The old pistons that I have are also Speed Pro which are 30 and the only issue I can see with them besides being dirty is having a little scuff on the skirts. The machine shop said I can still use them with the old rods that are attached to them but everything else I am putting inthe motor is new.
Should I reuse the pistons or hold off and get new pistons? If so what are good cheap pistons with a lock rings so I can use new racing rods?

 

First question I have is why are you looking for cheap pistons to use with racing rods?

 

I pretty much spent my money on everything else. When I say cheap I don't mean $200 pistons. Something close to $450.

 

See if you can exchange your std's for .030's. Next I'd look at the Icons from Keith Black. They're made from 2618 alloy which requires a bit more clearance than a Speed Pro or anything else made with 4032 but it's a good light piston. Price should be in the $450.00 range.

 

.2500 IS 1/4 inch, so I doubt it.
I think you mean .0025 inches.
If this is the clearance, I'd say that is not enough for these pistons.
If that is just the wear, get the clearances using your Speed Pro pistons.

WHAT EXACTLY, is the clearance of all 8 pistons to the bores you have now?

Not wear, not taper. A good machinist can hone it straight if the clearance is tight.

Acceptable clearances for Forged Speed Pro pistons will be between .004-.009".

Anything less than .004" clearance, and your pistons will be scuffed to hell and back.
That's probably what the first guy who had these pistons did. If you run them tight again, they can be even worse than what you have now.
Good luck
Jim

 

How long were the pistons used? If a few miles, OK. Scuffing can be a problem. the ring lands wear after a lot of miles even if the pistons look good otherwise.