has any one ever tried to mill some 13b housings down for use in a 12a?
I dont need the o-ring groove im using fd irons on it.
anyone know where to find some 12at rotors without having to buy an entire engine for them?

 

I do not remember who, but this has been done with success.

Isaac

 

My question is - Why? Sounds cheaper to just buy some 12A housings....

I guess you want to use the FD plates and the whole o-ring isssue.....good luck with it and keep us posted!

 

Here you go:

https://www.rx7club.com/1st-generation-specific-1979-1985-18/will-these-fd-rotorhousings-fit-my-12a-motor-696169/

He also cut new o-ring grooves since he was using earlier irons.

Keith: The reason is that the supply of new 12A housings has pretty much dried up. You have to go with used (unless you are lucky) and most are getting to the point of being quite worn. Another advantage of this is that the chrome flaking usually occurs at the very edge of the housing, so you could mill a 13b housing that has chrome flaking and the chrome flaking would be gone after the process.

 

Except that it's not.

The problem with FD side housings is, what do you do for an intake manifold?

 

Well... the FC engines that I've pulled apart seemed to wear in the center, not flake at the ends.

The flaking, incidentally, will always occur at the edges. The chrome flakes off because of fretting wear against the side housing. Nothing you can do about it except file the last few thousandths of chrome off of the rotor housing.

I've noticed that blown apex seals tend to do damage to the edges, too...

It's a shame that 12A rotors seem to wear out at about the same rate as the rotor housings. What good is a new rotor housing if the rotor is splayed-out trash?

 

Has this been done more than a few times, and how much would a task like that cost?

Just curious why the major companies don't due this since there are plenty of good 13b housings with chrome flaking getting thrown in the trash. Seems like a good idea. They could even grind down the 13b and grind in 12A lettering.

 

It is only recent that mazda dropped the new 12A parts. Seems this year we started seeing the high cost for the housings appear in the used market.

I have looked at it, to much stuff going on and have not pursued it yet.

-billy

 

any new updates?

 

Check out www.goopyperformance.com for rotorhousing resurfacing. They started this a few years back and will save many housings because of it.. Read up on it. Lots of excellent reviews.

 

I actually have some 12a housings that were milled down from 13B housings, which I dropped in just a couple of months ago. As 12A housings are nearly impossible to find over here, that was really my only option.

In Australia, the police are fairly strict on the certifications around engine swaps, so the "13B" markings were ground off and "12A" inscribed. A very tidy job, and looks (almost) completely standard. Will try to take a pic and post if anyone is interested.

I paid $190AUS per housing (and had to supply the housings).