lapping
 

ok guys I have an 80 that I'm building a new 12a for. However I cannot find a machine shop near by to have my housings lapped. If anyone nows where to find a shop in the northeast please let me know. I live in the capitol district area in new york. And what is the machine or the finish specs for the plates because a local industrial machine shop thinks they can do it but I want to make sure they don't destroy them. Basically in technical terms what is it I'm asking them to do? Thanks guys.

anyone

You are asking them to level the surface (I believe Racing Beat recommends no more than .004" removed). IMO, I would have a trusted shop perform the task. While its a pain to put them in the mail, it's a better idea to have someone do it who has experience in the matter.

I can't remember if your side housings have the nitrade coating or not. If it does, they could end up removing it if they lap the housing too much.

EDIT: I had said that they definitly do, and then I remembered that you said it was an '80 motor. If I was to actually say anything about a 12a I would be talking out of my ass. The rest of the post is true for 13b endplates though. I believe RB re-coats them with a flame spray process, or at least offers the service. I know that they use this spray process to make the hard finish on their aluminum side and intermediate housings.

I have heard from a lot of good sources that unless your housings really need lapping badly you likely won't have as good a housing after lapping as you would just using it because of the finish issue.

If you've ever drilled into a housing for porting it's an interesting feeling when the drill bit hits the Iron and starts going through like butter. It's like going through a piece of sheet metal on a wood block.

I don't mind shipping I was just hopeing to find someone near ny not on the west coast. They don't look bad there is almost no visable wear on them I havn't put a guage to them yet. I might just skip the lapping?

I wouldn't lap them. I can see wear on mine, but the step wear on them was almost immeasurable. You can see that the finish is different where the seals run over, but you can also see the marks from the original factory lapping. That's with 86k on the housings.

Unless they've seen extreme mileage, multiple builds, pitting from rust, or catastrophic failure side irons are usually good.

This is just one man's opinion though. I'm sure someone somewhere would tell you that you should lap them, but it's my experience that a lot of good builders won't.

I would suggest not to lap the housings if you don't need to.

just get a lapping stone and do it yourself :)