I just picked up a set of Olds pistons never been installed and I noticed that every piston has what appears to be micrometer readings written on top of each one. They are all very close according to the handwriting, but there is some variance. Do that a problem? The pistons are in the garage, I am not, so I cannot be specific right now. What is an acceptable variance?

 

Harvey, this is a good question to ask.

You should have written down those numbers though...if you really want opinions from all over the board.

Get a good machinist, he'll fit those pistons to the bore properly. He might also tell you if they are right for your expectations or not. That is the man to ask.

 

I had a new set of Wiseco pistons with hand written numbers. It was the weight of each piston. My numbers were very close to each other but not exactly the same. Not sure if it would be the same thing on Speed Pros but not sure what else it would be. I am sure others will know for sure.

 

gram wt - more than likely

 

Does this help?

 

Looks like .030 455 pistons? 425 is 4.125. And +.030 wp7ld make 4.155?
L2323 is number for 455 pistons. So 30 over 455 is what you have

 

if those are micrometer measurments i wouldn't trust them, if you use them just take them all to the machine shop and have them individually fitted.

 

I have four Olds, but only one 455 and it is already in a car a running pretty well. It is a 72 455 with "G" heads. It is likely an 8ish to 1 compression engine and would benefit from these pistons. The car currently runs 8.43 eighth mile times driving to and from, maybe a 45 minute trip one way. I think it has more in it the way it is. A friend came across these pistons and I could not pass up the deal. The reality is that I may never use them...

 

This is the car with the 455, I am just thinking to go into the engine and bore it, press off-on the new Pistons, plus rings and my preference, balance the assembly, etc. that would drop over a grand to raise the compression, maybe a point. When I want to paint my 70 Supreme AND my 68 convertible, I'd probably rather sell the piston set and move on! Ugh!

 

Those don't have the F in the number. The older ones weren't forged AFAIK so you might want to double check that.

 

That is interesting, the box part number label definitely has the "F", why would the pistons not? How can I tell by looking if these are forged pistons or not?

 

the button in the middle?