Side housings specs / factory rebuilt identification
 

Two questions…

1. Where do I find or what is the acceptable tolerance range for side housing thicknesses? I want to understand if irons have been lapped previously and what the limit is if I lap them during a rebuild.

2. Can you tell if an engine has been factory rebuilt? Are they stamped or otherwise identified?

Thanks!

Not sure if this will help. https://www.foxed.ca/rx7manual/manua...ria%201979.pdf

That helps immensely with inspection and rebuilds specs, perfect! Thanks!

Still curious about how factory rebuilt engines were identified and if there is a way to tell if side housings have been lapped, previously. I see this hand stamp on the front iron, but don’t know if that is original or a sign of a rebuild. I find no other markings anywhere.

https://cimg0.ibsrv.net/gimg/www.rx7...836355cde.jpeg

Mazda has a couple different rebuild facilities over the years, and they had a couple of different ways to ID a rebuilt engine.
so the old, pre 1997 rebuilds will have a stamp in the front rotor housing, usually its got a serial number and a date
i think this pic is actually an Atkins rebuild, but its something like this
https://cimg6.ibsrv.net/gimg/www.rx7...41cc0e73cc.jpg
the post 1997 engines have a blue tag on the front cover, it'll have a part number, date, and serial number.
https://cimg3.ibsrv.net/gimg/www.rx7...19abf64e34.jpg

other signs of a rebuild are if the any of the housings, or flywheel are painted. also if there are any marks on the tension bolts or the big rear nut.

ive never seen any rebuilder stamp the front iron like that, but obviously someone did.

Where I’m headed with this is to understand what I’m starting with prior to lapping side housings. My rear has a step of about .004”, mid about .0015” & .0025”, and the front zero. Weighing options for lapping, nitriding (or not), or buying better iron(s).

PO of this engine stated that it was a Mazda rebuild, so I’m looking to confirm this.

Let me throw a potential bomb out there which I’m sure has been discussed, but I’ve not come across…anyone have experience with running lapped side housings which have not been re-nitrided?

yes, they will wear out much faster.