>When rebuilding and or modifing a rotary engine when does it become necessary to re-balance the rotors?

>Racing Beat recommends the rebalancing of the complete rotating assembly (including; both rotors, main pulley, front and rear counterweights, and the eccentric shaft whenever you plan to run the engine regularly above 8500rpm's or if your running a non-standard assembly.



>In my case I think it's the later. I rebuilding a 87 Turbo II that needed a replacement rear rotor. I was able to locate a good 87T rotor, but I feel unsure about using a rotor from a different motor.

>Do you think I'll need to get the whole assembly re-balanced now?

>The guy's from "Pettit Racing" who ruined my old rotor (long story) assure me that I can run the new/old one they found for me because the weight-balance marks on the rotor face are close enough to be used safely together.

>Help a brother out and give me some advice because I don't know of anyone out here in NYC that I could trust to rebalance this suckers.



PK797

NYC

as long as you are using rotating parts meant for an 86-88 t2 its fine.



mike

Ah, good. All those recessed circles on the outer tips of the rotor sides make me nervous about rotor orientation on reassembly. That and I have an original rotor and one from another engine going into my final rebuild.

Ya Guys

I look into this for myself and even spoke to the guy's over at Mazda Competition and found out for sure what rotors can and cannot be used together.

This is the story:

As I mentioned earlier, each rotor has a small weight mark stamped onto it. This weight mark is in english, usually from "A" thru "E" and can be found stamped on the gear side of the rotor in between the oil seals and the side seal grooves. These are smaller in size than the larger "S" lettering stampted in the corners and will tell you the relative weight scale of that perticular rotor. From what I was told you can use and too rotors together that are no more than too letters apart in weight. In other words a "A" type rotor can be run with a "B" or even a "C" type rotor, but you don't want to run a "A" type rotor with a "D" or a "E" type rotor.

That's it.



Paul K.

NYC https://www.nopistons.com/forums/pub...DIR#>/cool.png

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Oh man, thanks for posting that! I knew that the letters had to mean weight but just didn't know to interpret them. My rotors are D and E so they should work out.



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