I am new to the RX7 arena and to rebuilding rotary engines. I am working on a 1983 12A and I have a question about the rotor housing. One of mine has some flacking of the hardened area . So, I have been on a quest to purchase a replacement here in the Mpls/St Paul area. I have seen a few of the housing that are for sale and they seem to be in the same shape as the one I already have, or worse. I have been told that this amount of flacking is insignificant and that I don't really need to replace my housing.

Again, I am new to this game so I thought I would put a picture here for others to review and comment on.

So gents, what say you? Is this rotor housing usable or should I be replacing it with another one?

 

i am no genius but I dont see a problem with it as long as the flaking is not occuring in your compression stage of the cycle. if it is, then the apex seals are not going to seal correctly causing you to have low compression. but I could be wrong.

 

uhhhhh well try polishing it but ive seen people fixing it with epoxy but i dnt know how long would last

 

I suppose epoxy might work but it is not the kind of thing I would try. I am too new at this rebuilding game to try anything that is not in the manual.

If I were to be so bold, I might go with this stuff: http://www.jbweld.net/products/jbweld.php

My biggest problem is the heat generated within the rotor housing of a running engine. My guess is that it is above 500 degrees which is the limit for this epoxy.

Come on, where are the experienced engine builders?

My 'thanks in advance' to all those who venture their opinion.

 

Do not use epoxy. the vibration and heat will bring it up. You can use that housing on a buget build. If your staying NA with stock ports you should get a good service life out of it.

 

budget or not do it right the first time to save your self the head ache

 

Here is an opinion from an engine builder:

Those housings are junk. Use them as paper weights.

 

Rich I know you are like me and usually deal with just 3rd gens, have you seen many 12a housings, his are actually in decent shape compared to what are out there

Not ideal by any means but I would focus more on the area above/around teh spark plug holes and for any extreme cracking around the plug area, as this is where your compression is made.

You will get some blow by in the power stroke with the housing you have but unless you are really lucky or willing to spend big money then be prepared to be satisfied with the results you get from that housing.

Once again, not ideal but assumming the rest of the housing is in good shape it will run. Im pretty sure the 12a stuff is hard to come across but if not just pick up a better housing. Mazda definitely had not mastered the chroming of the rotor housing surface at that point.

 

Point taken, snuggle bear

There is a pair on fleabay that might work for you, search for this title:

Two 12A Mazda Rotary Housings One Rotor RARE Vintage

 

You always know the right things to say

 

well yeah umm they are junk if you wanna hear the real deal then contact your buddy mr common sense if you see the housing like that ..... then you know it wnt work and about the epoxy i thou u wanted to just get something quick and not caring about what could happen but anyways ive try that in only friends race cars and it works fine you just gotta know what your doing

 

You could probably get them CerMet coated, costs a bit though.

 

OK guys - I have seen the light. Base upon the varied opinions we have here I have decided to purchase a replacement housing. Thanks to all for your input.

 

if its a small problem now, its only gonna be a big problem later on, I would change them. Never do a rebuild especially with parts that MIGHT work, lol