supracosworth

Dear gurus, a couple of questions on how many old parts can I scavange for my rebuilt. On disassembly, I discovered one of the housing to be "good" and the other one apparently "bad" as follows:

1. On the "bad" housing, in the area where combustion begins, there is a patch of smooth undulations of approximately 2 inches in diameter. If I run a straight rule across it, I can see light under the rule. The peaks and troughs appear to be less than 0.1mm and as I say, the wear is smooth and not caused by grinding of foreign objects. Any idea what causes such localised wear? Can a lean condition cause this? Can I just sand it flat and what sort of tolerance is there for the housing to be worked on in this manner?

2. On the "good housing", the housing is basically straight throughout save that the apex seals have run 1 to 2mm wide smooth grooves around each side of the housing's edges. These grooves look like less than 0.1mm in depth but I can see if I run new apex seals over them, they might not seal as tight as if I just continue to run the old "seat in" apex seals.

3. The side seals, corner seals, oil seals and springs look okay to me (but see 4 below) but is there a more scientific way to determine whether these items need to be changed? What's the case against reusing them? All four side plates are scratch free and appear to be absolutely flat when I run the edge of a steel rule across it.

4. Looking at the side of one of the rotor, its burnt dark as if combustion also takes place INSIDE the area sealed off by the side seals. This contrasts with the opposite side of the rotor which is still almost pristine white with no sign of combustion. Does this mean the side seal on one side is bad?

5. The Racing Beat site appear to be down. Is there anywhere else that I can get some street port templates? Last I heard, the Racing Beat templates appear to have the forum's approval?

6. Lastly, the above engine is not mine, I'm just helping a friend to rebuilt it for free and he's on a real tight budget. My own engine is also suffering from a blown o-ring seal and I'm on an even tighter budget . After experimenting with various brands of block weld stuff (except for the CRC Copper Blockweld which you guys swear by), it's still blowing. I don't live in the States and there's absolutely no rotary expertise here. I've searched the internet and cannot find any online vendor for this CRC stuff. If you know of any online vendor for the CRC Copper Blockweld, please let me know.

Sorry for the long post. Any help would be much appreciated.

Regards


Michael
(P.S. This email is SARS free)

Trexthe3rd

First of all, do a search for rebuild you will find tons of info. Look for the website to purchase Bruce Turintine's 13B overhaul video. Or get a RX-7 service manual. You cannot determine the state of the housing by just sticking a straight edge against it. You'll need a dial gauge witth a magnetic stand, anything less you are playing lottory with your engine.
As for the porting template, you can get them from www.mazdatrix.com as well (it's the same as the Racingbeat set)

supracosworth

Thanks for the info. We've already ordered the video and a set of o-ring seals and gaskets from Rotary Aviation (i.e. without the apex seals and "hard parts")

http://www.rotaryaviation.com/overhaul_kits.htm

Incidentally, has anyone used this kit before and what's the verdict?

silver93

i am pretty sure bruce supplies the kits for rotary aviation. i bought mine direct from bruce, and if it's the same thing, i was very happy with mine. I bought the master OH kit and gasket kit. Also, the 13B OH video has detailed instructios on cleaning and spec-ing all the parts, includings corner seals, springs and housings. good luck