MIKE-P-28

iTrader: (1)

I got a 1985 RX-7 GSL 12A , just street ported with headers But Im in the process of a re build. After scrounging through my little parts pile, I found 2 nice rotor housings The front, intermediate, and rear were ok with a little grinding. But heres my problem, I got 2 rotors from 2 different motors, which are good and straight, but they are both marked F & N (in the part of the rotor where the spark plug fires) I guess that means they are both front rotors? The damaged ones have a R and something else on them... I have weighed these things & stared at them, and the only difference I see is the front ones have (how do I expalin this) 3 little circles. If you look below the corner seal on the rotor, it has 3 circles imbeded in the steel of the rotor, it has this pattern twice. And the third time is a single circle... Is it gonna hurt if I go ahead and put this thing together... Im desperate to go raise hell again LOL

nimrodTT

Take a closer look at the faces of those rotors, you'll notice the dishing of the faces swoop in alternate directions. And though you could assemble it like that, do you really want to?

Also, did you port the engine yourself? If so, I might have an extra rear rotor that I'll trade for some porting templates.

MIKE-P-28

iTrader: (1)

No I didnt port it myself, I got lucky to get a blown motor that had already been ported... Tho $40 for templates would be a good trade for a rear rotor... I beleive they were $40 from mazdatrix? Let me know, Ill order them and send ya the templates Im gonna need to try and port these rotor housings too That oughta be fun...

JIMMY54

iTrader: (2)

Thinking about doing the same as you, would it be hard to port the motor yourself with the templates? and do you happen to know what tools are needed for the porting? I'm gonna find out how much a shop charges just to port the motor. I will assemble it myself. Next step is to decide which kind of porting do I want. With me I just want over 200hp. And I found out small porting will able you to turbo the motor if you decide too. But I don't want the extra headaches. N/A seems right for me and the engine bay will look just like 1984 with minor changes.

REVHED

Large porting and turbos go hand in hand. In fact alot of the quicker rotaries are running bridge or peripheral ported turbos and making heaps of power. IMO bridge and PP turbo motors kick ***.

JIMMY54

iTrader: (2)

so am i to understand that you can port it however you want, you can always add a turbo later? but those are serious mods right there, i'll do a more suttle port on mine. thanks guys

MIKE-P-28

iTrader: (1)

I really dont know alot about perhiperal port or bridge porting, but I do know that street ported isnt easy to do by yourself. Trust me I ruined a set of 3 side housings. Got the whole entire SOB back together and in the car and guess what it didnt start! I called Mazdatric and told him what I did and he said on the intakes if you go any towards the eccentric shaft, the motor is a really nice door stop and conversation piece Now with the templates they just show you what has to be cut away, doesnt show what shape to make it beyond the scribed line. With exhaust porting I dont think anyone will port them without you first buying new rotor housings. Or at least at racing beat or mazdatrix, it says exhaust porting preformed only on new rotor housing supplied by them etc. By the way a real nice dremel and some sand paper is whats required to port it.

On bridge and etc porting, I always heard they dont idle very good below like 1500 rpm. Is that right?

By the way ANYONE got a good rear rotor for an 85 12A reasonably priced? I need one to finish this sob, im bout to just drop this damn old motor with adequate compression in my 80 and drive it. Im getting tired of driving my 1990 GXL with no Boom Boom and a freaking automatic!

nimrodTT

It turns out my extra rotor is a front, so it looks like youre outta luck. As for those templates, they're $40 for the intake and $40 for the exhaust.

Also, on the note of bridgeports and peripherial ports matched with turbos: it's really not a good idea. There are ways to make more power, more efficiently with your rotary.

MIKE-P-28

iTrader: (1)

DAMN, oh well, I guess Ill keep looking... Thanks man

REVHED

Bridge and peripheral ports will make more power, have a wider power band and have better V/E than stock or street side ports on ANY engine whether it's N/A or turbo. It's a proven fact. Whether or not it's a good idea on a street car that spends alot of time idling and cruising at low revs is a different story.