Neck deep into my rebuild and I discover this "Gouge" for lack of a better word. To make this more interesting both housings have it in the same spot. Its maybe .002" deep and rough to the fingernail. I thought it was carbon from burning so much oil (thats the reason for the rebuild) but it is actually a grove. Has anyone encountered this in a rebuild before? It is just before the exhaust port so it is not likely to cause compression lost. Plus compression was awesome before the rebuild. Should I consider not reusing them in the rebuild? I'm tight for cash because of a recent divorce... https://www.nopistons.com/forums/pub...IR#>/wacko.png But if I have to I will get some new one.

Very common.



You can reuse them but you will lose out a little bit on compression. Some people use Hurley seals on those housings as the join between the side and main pieces of the apex seal are away from this area in the hurley seal. The flaking is usually caused by the factory seal side piece, sometimes due to lots of high revs.



The attached pic has a new hurley seal and well used mazda seal. The side piece on the stock mazda seal when new is actually at a point.

I also found the same type of gauge in my front rotor housing. It actually went the entire perimeter of the bottom of the housing, from say 4 o'clock to 8. I went and bought a new one but they are expensive.

It's common as stated above, usually you can reuse the housings, just flip the apex seal over so the corner assist peice sits on the good side of the housing... I wouldn't recomend reusing them on a engine that will boost more than 1.1kgcm however...