I have pitting on all four rotor surfaces at the bottom of every iron. Can these be used or fixed in any way?

 

you can get them lapped. there are measurements / procedures for spec'ing parts in the FSM. i wouldn't want them used as-is in my motor but i'm no engine builder.

 

That all depends on how deep the rust has gone. The only real way to tell is to spend the money to have them resurfaced.... but if you are on a tight budget you are better off taking that money and buying a replacements.

 

Looking at the 87 fsm, the only measurements / procedures for spec'ing them are the side housing warpage limit 0.04 mm and side seal wear limit 0.10 mm. I do not own a dial indicator gauge to check the side seal wear. You would want to check them after getting lapped or before?

 

Any machine shop can lap/resurface these?

 

Not any machine shop can properly lap them. The amount of material you can reasonably remove is only .002" or so before you need to have them re-nitrided. You need to get ahold of a dial indicator and measure that pit.

Personally I would not use these, if you're going to the trouble of assembling a motor just pick up another iron. They are not that expensive used.

 

those are s4? use them as junk irons to practice porting and get low mileage jspec irons

i don't trust aftermarket nitriding

 

Well if I was to lap/resurface these within spec, what type of machine shop would be able to do this?

 

You'd have to call a machine shop and ask them whether they can flatten it. Don't say "rotary engine iron". Just tell them you have piece of cast iron with a machined flat surface and give them the dimensions. Ask them if they can machine it again. You probably won't have much luck at automotive machine shops because they probably won't have a machine big enough.

You will probably find it cheaper to buy a set of good used irons then to have these lapped.

 

I heard you shouldn't lap the 13b irons because of the size of the coolant seals and them being too big. If you decide to lap them there is a very specific tolerance to how much you can take off before the coolant seals are too big for the groves. Sorry I don't know what the number is offhand. I would buy used ones that are in good condition though as the machine shop will probably charge you a lot. I read that resurfacing was more common on the 12a. Are the 12a irons nitrided?

 

semi offtopic:

if you have some good irons but lets say one could be lapped, could you get away with just lapping the one or do you need all 3 lapped? even if the other 2 are within spec

 

These irons are 2k miles into their re-use in an N/A build.
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/susceptible-wear-question-796615/

But if I was running turbo I would be getting some low mileage units from Japan2LA.

 

lapping is $280.00 for a 13B..

I have looked at your pics and I am sorry to tell you.... that corrosion will not be able to be cleaned up...

Those plates are done..

You will be throwing $280.00 away ...as once the corrosion goes past the shell hardening of the sideplate, its toast..

Dont waste your money lapping, find another set

 

Actually I have cleaned up the surfaces with fine emery paper per the fsm procedures and it cleaned up all of the carbon/corrosion build up that you see in these pictures, but there are two spots that the pitting goes pretty deep. So I am not going to use these for anything else other than port practicing. Thanks for everyone's input, I was just trying to weigh all of the options.