I am currently having my engine rebuilt by Rotary Resurrection (Kevin) and so far I am very pleased on how things are going. Kevin is very responsive to my e-mails and keeps me informed every step of the way. Today he e-mail me pictures of my motor broken down and the damage was pretty light. My rotor housings are cracked on both side of the leading (larger) spark plug hole inside the rotor housings (See pictures). Kevin has given me two options and I just want to see what the RX-7 community has to say.

Excerpt from e-mail:
The only "fix" is to replace the rotor housings; new housings or lightly grind down the cracks. This keeps them from swelling out as much and wearing into the apex seals, and keeps them from acting as a speed bump for the apex seals to jump over. I will still lose some compression in that spot, but not as much as if you leave the cracks alone. This is the only "doctoring" that can be done for these rotor housings to improve/restore them.

 

either new or a set of good used housings

 

whats your budget?
if its "large" get brand new housings

if its not so large, find good condition used housings.

Those are not something you want to mess with because likely if you do you will be sending your engine back to kevin in a year or two for another rebuild. Spend more now so you dont spend way more later is my motto on this car.

And run plugs in the 9 heat range when you get it back. NGK part number 5255

 

Do not use those housings, if at all possible spring for new ones.

The heat range of the spark plugs used is dependent on the boost/power levels run....... for example I run 10s leading and 10.5s trailing because I usually am at 20-22 psi.

 

I would only use those housings on a ghetto non turbo engine build