13B-REW Rebuild Inspections
 

Looking to start budgeting out my engine rebuild, but I have a few questions regarding my current engine components (questions below each picture). Working on a complete car/engine rebuild, just finished the trans and now onto the engine: 1993 RX-7 R1 Build I have no history of the engine, the car had 85K on the odometer. It didn't have any hot/cold starting issues and did not smoke. Engine will be rebuilt with a mild/full street port, OEM seals, and single turbo conversion. Looking to have a "brand new" car once I'm complete, the car is not and will never be a DD. Thanks in advance.

Rotor Face Machined/Tool Mark Finish:
Attachment 667334

Is it common to have a rotor with smooth faces but machined/tool mark pockets? All REW and MSP rotors I have seen are textured?

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Rotor Face Marks (Japanese Characters?):
Attachment 667335

Are these marks identification Japanese characters? Assuming not impact/dents since rotor housing are undamaged? Also, another view of tool marks vs smooth rotor faces.

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Rotor Side Pitting:
Attachment 667336

Pitting only occurred outside the side seal, exposed to moisture while car sat idle. Would this pose any reliability issues, that picture is the worst case?

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Side Housings (Front, Inter, Rear):
Attachment 667337
Attachment 667338
Attachment 667339

I have yet to measure the housings for seal wear depth. The "pitted" looking texture over the combustion phase is just as smooth as the intake phase. Other than wear from the seals the entire face is smooth to the touch.

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Rotor Housings (Green - Starting Flake / Red - Flaked Off):
Attachment 667340
Attachment 667341

Most of the wear/missing chrome is at 2mm, with some areas less. No spark plug cracking, & apex lift above exhaust port. I am not reusing these, but wondering if there is any value in selling them? Would these be any value to a drag car?

I wouldn't use that housing on a turbo engine due to the chrome flake. A cheapo 1986 FC or something, sure.

If I remember correctly, they started machining the bathtub combustion recess in 1989 (series 5 FC and later). Previously they were cast.

Thanks for the reply.

Yeah, the rotor housings will probably go up for sale at some point. I'll look around and see what I can get for them.

My question was more in regards to the rotor faces themselves. The smooth rotor (pic #2 - right) also has some type of permanent 'stain', but smooth to the touch. I was trying to figure out why one has machine/tooling marks 'lines' and the other is completely smooth?

I would bet the engine was opened at one point. Do you have any pictures of the rotor "tips" on the smooth rotor? I have some suspicions...

I will just attach the photos so they retain a larger resolution. These are the only three photos I have of the cleaned rotor.

One thing that had me confused is that the rotor face isn't a constant radius arc, so using a grinder with the rotor off centered shouldn't work. Unless Mazda did produce 'smooth' faced rotors.

Out of curiosity, what is it that you are looking for on the corners?

Those machine/toolmarks on that rotor that extend into the bathtub area are strange. Normally rotors look like the other example on the right (smooth).
Odd.

Someone posted a while back that the ridges on the rotor faces occur as the cutting bit starts to wear. I have seen them both ways.

The discoloration in the combustion area of the iron is just the nitrided surface reacting to lots of heat, normal for high mileage stock motors.

The pitting outside the side seal area is just the soft metal that is sprayed on at the factory, normal.

If we can get a picture of the water jackets near the leading plugs... If there are small recesses machined there then they are REWs.

Thanks everyone, the texture difference just struck me as odd when I pulled them carbon free out of the Zep bath. I'll take the time and inspect the rotor to ensure they are from the same 13b engine version and what version that is. All the bearings were completely worn out, large areas of copper showing through.

Might be a week or so but when I get time I'll inspect all the parts to determine what version (if other than REW) the components came from.

One last question, am I correct in assuming the indents on the rotor faces are Japanese characters and not damage?

i've pulled NEW rotors out of the box that were ridged like that, and NEW rotors that were smooth. remember new rotors get a plating that's gold colored, so new ridged ones are ridged and then plated

conclusion? they needed to change the bit