This is my first rebuild/porting experiece, please be kind in your replys. I am going to do this correctly, yet as cheap as possible. Okay, heres the grounds of the subject:

12a half-bridgeport
2-piece stock apex seals

Questions:
1.) Should (can?) i use 3mm solid apex seals?
2.) What is the advantage of the 3mm solid apex seals?
3.) Where can i buy the soft seals for the engine internals? link please!

 

1. The way I understand it, you would have to have the apex seal grooves in the rotors milled out to accept the 3mm apex seals. I would imagine this isn't cheap.
2. I don't know
3. AtkinsRotary.com
RacingBeat.com
RotaryAviation.com
Victoria British (no online catalog)

 

www.mazdatrix.com for the soft seals

i'm not sure, but on 12a rotors i think you can use one piece seals, would be good for a bridgy. check mazdatrix too for them.

 

when you say "solid" apex seals what are you referring to? i know they made carbon seals for bridgeys and peripherals from way back, but i don't know if that's changed. i never built a bridgey or peripheral so i haven't bothered to remain up to date with the available parts.

what i do know HAS NOT changed is that the stock apex seals will do you very little, if any, good in a bridgey because you'll either **** them up (along with your housings) in short order OR you'll have to limit your RPM in some way - which kinda defeats the purpose of building it.

 

all pre-1986 engines have 3 mm apex seals, with the exception of the really OLD engines, which had 6 mm. so there is no milling to be done on his 12A.

 

Ive been reading all about rebuilding/porting on www.nopistons.com and i have found out that it IS okay to use 2-piece apex seals on a HALF-bridgeport. As long as the apex seals are still in stock limits (measures), it will not hurt to use these in a half-bridgeport.

When i say "solid 3mm apex seals" im talking about the ones listed on the atkins rotary webpage. Im not really sure about them, i wish that atkins would list more about their products on their webpage.

MORE QUESTIONS:
1.) I got kind of confused when i pulled apart my 12a engine. There are 5 housings, 3 of which look to have "intake and exhaust ports." I thought that i only needed to port 2 housings, the two that have just one intake port them (not the intermediate housing?) Could somebody please elaborate on this for me? I really do know what im doing. I just want a little more clarification/direction before i get into the eccentricities of the rebuilding and porting.
2.) Does anyone know the cheapest place to buy the water seals that go in the housings?

EDIT: I want to purchase engine parts as seperate as possible. I think the only part that i need that i havnt been able to buy seperate from a kit is the water seals that go in between the housings.

 

i'm assuming a half-bridge would be just porting either the intermediate housing (the one with ports on either side) or just the two outer housings, but i'm not sure. think of the layout of your engine. air/fuel gets sucked through the ports into the chambers from BOTH sides of the rotor. either way you port it, if you stick with doing just the intermediate, or port the outer housings, the rotors are going to suck a/f through one bridge port and one normal port. hope that helps.

 

ooops!

i'm sorry for almost giving you wrong info. i completely missed where you said HALF-bridge.

yes, you are correct. only bridge the secondary ports (the 2 outer ones), leave the primaries as streetports.

 

Why go half... go all the way!!! Well, I thought about it too but NAH!!! Im going P-Port instead.

 

Another question!

Can i (should i) use 93-95 style corner seal springs with my 12a corner seals and plugs?

 

I've heard that the 12As had 2mm apex seals. I've also heard that the 2mm are the better ones to use. Don't know about that with a half-bridge though. Correct me if I'm wrong people.

 

1. I think you might be in over your head if you don't know what the housings are. The answer is you need to port ALL 5 of them. The intermediate (centre) housing contains the primary intake ports which are typically street-ported on a half-bridge engine. The secondary ports are located in the end housings and these will be bridge-ported. You must also port the exhaust ports in the rotor housings. There is no point trying to get more air in the engine if you can't get it out.

2. You need to buy an engine gasket kit which is basically the minimum needed to tear down and re-assemble an engine. This contains the water seals. You will probably also need apex seals, side seals, corner seals, oil-control seals and o-rings.

 

all single dizzy 12A's were 3mm 2 piece apexes, all 2 dizzy's are 6mm carbon 1 piece apexes I've built many of both.
If your going 1.2 bridge then bridge port the front and rear iron housings and street port the middle housing and port the exhaust too. Take your time and do it right 1 mistake and your back to square 1 also as a tip until you get the feel for just how far you can cut before you hit water jacket I'd suggest being conservative with material removal you can trash a housing fast.

 

Thanks! Oh, i when i was talking about only porting 2 housings...i mean only bridgeport 2 housings...i know how the rest goes...but thanks anyhow. Trust me, i will take my time and do it right, i have at my disposal, a high powered die grinder and a high speed dremel. I think that i am going to use the dremel because it will be harder to make large mistakes and the work seems more precise from what i hear.

 

Is it high speed as in 2 speed or multi speed dremmel? You want the adjustable dremmel so you can put that thing on slow to make small mistakes even smaller.