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Hello, few weeks ago i disassembled my first 13B and checked out all the damage, i had my side housings ground down by a bench grinder without coolant (they now have rough surface) later ill palm sand them (what i red from other posts). I wanted to ask yall what you thing about the damage and what could be saved/reused in the build.
I am thankfull for any feedback
front side of the middle plate, took about 0.2mm of material and there is still some damage visible, water seal groove height is about 1.5mm what i messured closeup photo of front side of the middle plate closeup photo of front side of the middle plate this is the back side of the middle plate and i took here about 0.05mm of material here, the water seal groove here has 1.7mm height also back side of the middle plate
[img alt="this one is i believe back plate and here i took about 0.1 -0.15mm not sure how much now,
the water seal groove height is about 1.65mm"]https://cimg1.ibsrv.net/gimg/www.rx7club.com-vbulletin/600x800/img_20260124_150315_24406e94acdb8e8d92f0391b4ed506 9466aec332.jpg[/img] this one is i believe back plate and here i took about 0.1 -0.15mm not sure how much now, the water seal groove height is about 1.65mm another picture of back plate this one is front plate, on this on i took about 0.1mm and the water seal groove height is about 1.65mm and another picture of front plate
i find the rear rotor pretty good except the tips where the apex seals slide are little coroded in one place.
the front rotor made contact with rotor housings and side plates, but the apex seal grooves are in spec and apex seals move freely in them.
and about the contact with side plates, where it touched i measured about 0.05mm less than then in non touched places.
i will also replace all bearings.
the engine had catastrophic oiling problem and the front bearing was totally dead.
Take good care to make sure everything is in spec for re-use. I can tell you firsthand that .005"(.127mm) MAY get through the hardness layer of an iron, and make a mess of things.
yeah i know about the nitrided layer and i do plan to give them to local shop for gas renitriding, i also took out the oil filler pipe or what is it called and all other things that i tought should be removed beforehand.
i am little more worried about the water damage/corosion, what are your toughts about it? should i let them grind down little more until only healthy steel is visible?
FWIW, the bottom part of the plate is not part of the compression stroke so it will not affect the compression of the engine. If the pitting is too bad, it could affect seal life long term but only you can make that call. I'm sure someone more experienced will chime in but I just rebuilt my T2 engine that had some light pitting at the bottom on a couple of the plates and decided to re-use them.
I was little worried that the exhaust gases would slowly eat out pocket over time in the most corroded part of the middle housing if it wasnt flat.
I also read that there needs to be sufficient water jacket height so the seal would be good fit if you know what i mean. A took already about 0.2mm and the height is about 1.5mm which i dont know if thats enough space for new water jacket. So i am little curious if there is any safe way to enlarge the grooves by little bit. I tought that i could uses dremel with some carbide drill or smth like that. Any ideas?
yeah i know about the nitrided layer and i do plan to give them to local shop for gas renitriding, i also took out the oil filler pipe or what is it called and all other things that i tought should be removed beforehand.
i am little more worried about the water damage/corosion, what are your toughts about it? should i let them grind down little more until only healthy steel is visible?
Get a machined straight edge and some feeler gauges, and make sure you don't have an actual "dip" in the surface. It looks fine IMO. Rust/corrosion will stain a surface but remain structurally sound. Its going to spend the rest of its life soaked in oil.
This is a pretty good source of rebuild information. There are tips and tricks that some builders use that aren't covered in this, but here is come core OE info.
As for the rotors.. check the gaps, and look for deformation of any kind. This is critical for maintaining compression.
Thanks,i read the document and made decision. Ill make fine palm sand the surface on the iron and even on the housing. And slap it all together with new bearings, springs and gaskets.
Best of luck and let us know how it turns out! I'm using new housings but my plates were pretty similar to yours. I should be firing the engine up sometime in the next few weeks.
