Engine re-build questions
 

Hello rx7club,

I tore down my blown engine(first time) and found some rust and damage on the rotors and wondering if they can be reused. They Look pretty bad, please see the pictures. Maybe rust is ok but damage around seal area probably not. What about rework to 3mm? Should I order one of the jdm engines with 50k miles as alternative from ebay? or just get new rotors. But at the price of 900 each might be little too expensive.

Also there is damage from broken seal on the housing. It does not look to bad but I can feel it wit my fingernail. See some pics. Can it be reused? Its a 100 miles housing.

I would honestly consider getting a good condition used pair of rotors over going 3mm, but thats just me and I am *not* a professional builder.

If this is just going to be a stock or slightly modified engine then those rotors should be ok. Clean up any high points or burs and make sure seals wont snag while moving to conform to housing. That damage to housing may cause sealing issues if it's deep enough. Hard to tell for sure but anything bigger than a little scratch or normal wear usually warrents a new housing.

the rust isn't a concern. those rotors look like they might clean up enough to be used, i'd measure the grooves carefully though, the apex seal grooves look pretty V'ed in the pictures, and if they are, then the rotors are done right there.

it might be that the oversize goopy seals work for you.

Thank you guys. How can you tell if they are V'ed? If grooves need to be machined, what is the easiest way? This engine has big street port and T04r so power will be more than stock. I am planing to change to smaller turbo to make it little more track friendly but that if budget allows.

I think he is saying they need to be like this | | at the tip where your seals would be. Furthermore, if they are V'ed or rather \ / then the apec seal will probably wiggle around and that can't be good. Used rotors aren't too hard to find.

Run a seal through each slot and check the clearance at several points with a feeler gauge. You generally want .002-.004", depending on the seal and goal of the build. The gouge in the rotor housing looks deep. JDM engines are junk. Better off getting a mazda reman.

This: Run a seal through each slot and check the clearance at several points with a feeler gauge. You generally want .002-.004"

Than This:the rust isn't a concern. those rotors look like they might clean up enough to be used, i'd measure the grooves carefully though, the apex seal grooves look pretty V'ed in the pictures, and if they are, then the rotors are done right there.

it might be that the oversize goopy seals work for you.

Those rotors are still good. Also, If that groove on the housing is a concern, have the rotor housings resurfaced. That's it. You will be good to go.

before reading the comments i figured there would be a dozen "throw the rotors away and buy new ones" replies. they're fine to reuse, assuming they are still within spec after checking with new hardware. i wouldn't go trying to get 500-700whp with them though.

the housing i would consider a loss, which is too bad considering its condition otherwise. the groove looks too deep to resurface them and remove it(yes it could be completely removed, leaving you with about 20% of the chrome left on the housing, which will wear rapidly) so it will always have a small amount of leakage in an otherwise very critical area of the housing.

Does rotor need to be reworked in order to fit oversized goopy seals? What is the best way to resurface them? Can any machine shop do it?

The over-sized goopy seals are meant for rotors that are worn out of spec. This is most common on older rotaries. I found a lot of first gen rotors that were worn out of spec. Generally you want .002-.004" clearance between the rotor and apex seal. I've never found a need for an over-sized seal on a 13brew. Measure it to be sure. And no, I would not trust any machine shop. They need to have experience with milling rotors. If the milling is off any amount, the seal can chatter.