I just re-assembled my engine and forgot to check apex seal lenght. I installed 2mm 2 piece RA super seals and didnt think about checking the housing thickness to apex lenght. The rear housing has 2k miles and the front is the original. Because of the 2-piece desing I didnt really think how long they would be once installed them.

The engine is put back together and it rotates with some force. I was thinking it was a little tight due to the race springs. Can you guys show me the right way. I rather take the engine back apart if I have to then blowing it up at the first track event. Any advise from season builders would be greatly appreciated. This was the first rotary engine I tore down my self and rebuilt. If I have to take it back apart, HOW would I clearance a 2 piece seal?

Build thread:
https://www.rx7club.com/drifting-226/1st-rebuild-890499/

 

So you just assembled the motor without checking clearance?

 

There are two clearances you need to do. The rotor grove to apex, with which you will need a feeler guage, and a housing to apex length clearance where you measure the thickness of the housings at four quadrants and use the lowest measurement with a caliper , then subtract the length of the apex seal(s) and use the difference as your clearance. I don't remember the exact ranges you need to be in though.
Are you using new corner seals? If not then you should also clearance them as well.
My suggestion is that you download the FSM (manual) from this website, I belive it is somewhere at the top of the 3rd gen section.

 

I just simply didnt think about apex lenght because of the 2 piece desing.


I have the FSM and I know how to clearance a one piece seal.

 

The factory seals are 3 piece. It's like the "big" part of the RA seal is split, and then there is still a corner piece.

 

I know that already. I went from a 3mm apex seal on my last set of rotors, but the engine detonated and damaged the rotors. No I have gone back to a 2mm seal for the sake of not having to have the rotor machined to 3mm seals. I have a spare motor and i noticed the 3-piece apex seals. Im guessing the 2-piece desing lenght doesnt have to be clearanced. I have searched and searched, but could find anyone doing this. For now the engine is going in the way it is, because Im 99.999% sure everything I did was right.

I installed the apex seals just like the FSM sudgests.

 

Sounds to me like you know everything already, so what exactly do you want us to tell you ?

 

hahaha.....I dont know everything. I have built pleanty of engines, but this is my first rotary and I want to make sure the guys that do this all the time can answer my rotary noob questions.

It was hard enough finding cooling mods, oil mods, and portwork information. It seems like you need a top secret clearance to get the info.

 

"the engine detonated and damaged the rotors"

do you know WHY the engine detonated?

properly fixtured and tuned rotaries don't detonate.

hc

 

I talked to the guy that previouly built my motor and he thinks it was inadaquate fuel. I agree with him. I had 550 primaries and 1600 secondaries at the time of the tune session at PFsupercars. We added race gas to prevent the engine from detonation incase it happened and it did happen. The other thing I noticed when I took the engine apart was the one of the 3mm's was broken, but still stayed together in the apex groove. We were on our final run at 17 psi when the engine changed its exhaust tone and we knew something happend. The car was on the dyno for around 3 hrs. Lack of fuel and high heat was the cause to the engine failure. I have now added 850's and a water meth mix to prevent this. I am also adding a bosch 044 and a fuel pump booster. This time around I have learned a lot more about the rotary engine and feel comfortable in my build up to this point.