The Machine shop that pressed pins into my KB hypers and reconditioned stock 455 rods screwed up (orientation wrong) I was told that the pins can not be removed without causing micro fractures and the pistons are now garbage.....True?

 

Repeated pressing will effect the pistons in a negative way.
However your pistons aren't junk. Tell your machinist to use Small block Mopar(.984) pins. He'll need to hone out the rods and pistons to fit but he should do that anyway, as he screwed it up.

Hope this helps.

 

Just reverse where the pistons go, left to right bank. Of course, make sure the sizes of pistons vs. bores are OK, if they aren't identical (as is generally the case with today's machining processes).

 

First of all thanks for the reply, I was starting to worry. To give you more of the story, the pistons have a Quench at the top and when inspecting, I noticed that: 7 of 8 rods had tangs out (facing oil pan). So I lined them up in order of the crank and block by fillet surface (rod pair-small sides together and Fillets out) When I got the rods orientated 7 of 8 Quenchs were down, only one correct. I then got a second and third opinion on options, both said I should demand new pistons.

 

Oh, should also add I put all tangs inboard too (facing the cam/up). 7 Quench(s) down now!!!!

 

As is sometimes the case, you're wrong.

If the chamfer on the rod is on the wrong side with the quench in the right place(top), then it won't matter where he puts them in, they'll all be wrong, period. He could put them in a Pontiac and they'll still be wrong.

Again, have your machinist correct the ones that aren't right. If you need to go to oversize pins then do so. But remember the .984 pin is normally lighter, so if it's been balanced it'll need to be done again.

 

Thanks Cutlassefi, for the insight, what should I look out for, upon their return if he does the procedure as you described. How easy is it for them to create a, "micro fracture" in the piston or is this just KB trying to make more money?Now this will be stuck in the back of my mind! Is there anything, I missed with the logic I used to come to the conclusion they were wrong.

 

It'll depend on how carefully they pressed them off and on.
Check for tight spots, or anything that seems unusual. Unfortunately you're still at their mercy to some degree.

It still amazes me how stupid some machine shops are, or they just don't care. I'm dealing with a couple guys on here that have had various problems, none of which would have occurred had the shop just taken an extra 2 seconds to figure it out. And it's on Chevy stuff too, that'll really make you scratch your head.

 

I didn't realize the pistons have an off-centered quench. As for the chamfer, the rods I have used were good on both sides with centered bearings. I guess some aren't.

 

I'm pretty sure if you look at the rods real close you'll see that even if both sides are chamfered, the bearings still sit off center. And normally one side will still have more of a chamfer than the other.

 

Well I guess the silver lining is, a buddy of mine (second opinion) who showed me how to rebuild my Tranny (walked me through step by step) introduced me to my third opinion by dumb luck, just happened to be a retired Olds mechanic who turned machinist, has his own machine/auto shop and he still owns has a couple of 442s in the personal stable. So after the piston issue is over, I found an Olds specific shop!

 

Yes, On a couple of the rods I could not see the more chamfered side, I put the bearings in...then I saw the, "Light". Tough to see on two them they almost looked square!