mild street port

[t2rew]

i would like to get the templates from r.b to do a mild steet port and wondered if anyone else has done this.:confused:

[Glenn Butcher]

Hi Jason,

I haven't done this myself, but you couldn't go too far wrong with their templates. Doing the porting does depend on the engine also, I believe that the side housings and end plates from an FD RX-7 should not be surface ground - i.e. The normal way to do your porting is to port the existing housings then have them surface ground. With an FD engine you are best to port new housings. SOMEONE OUT THERE ANSWER THIS? (I believe it is because of the nitrided layer is only thin on the housings) - again RB could answer this.

Another question you should ask them is about the exhaust ports. Quite a lot of the power is actually made through the exhaust ports - I have never seen any mention of exhaust port templates on their site.

I think they can supply the porting tools also.

Let us know how you go.

REgards,
Glenn

[MikeLMR]

I know they do Exhaust port templates for the 12a ... not sure on the 13b tho' (i've not looked)... Its a little harder to line it up as there are no dowels to slot it over like on the inlet.
RB has a some very good write ups on porting and they seem to very responsive and helpfull whenever I've E-mailed them asking about their products.

On porting the 13BREW engines, I THINK the later engine housings have a carbon impregnated surface treatment (some sort of gas nitriding ??) so I presume thats why new housing are recommended (as some recomend people do with all Mazda rotary engines)

[WWW.EVIL7.COM]

Dont machine the side plate facings as it will stuff the nitride !

[Glenn Butcher]

Allistair, do the FD engines have nitrided housings? I am assuming they do. (They started that process for the RX-7's didn't they? - or was it earlier than that?)

Therefore - if porting side/intermediate housings you have to be extremely carefull!!??

[WWW.EVIL7.COM]

Yeah i think it was the 2nd gen onwards that got the nitrided plates , one slip with the die grinder while porting and its all over , thats why people always look worried when porting plates .

[Grizzly]

If you are thinking of doing your own porting Take your time and use low revs on the die grinder to keep good control.

You can get Racing Beat templates from Ro Techniks (as they are a racing beat dealer)

Chris

[Brett]

When I rebuilt my 13B (non-turbo) I had to surface grind the end plates, removing about 0.001mm. The engine has about 2000miles on it now and is getting better and better as it wears in. However, no one had told me about the nitride impregnation, and I saw no evidence of this when I was grinding the end walls. But, when I met up with Tim he said I'd now f'ed the engine by doing it! Now maybe he's right and the engine will be blown in a couple of thousand miles, but as no one made this info clear when I was making noises about my rebuild, I'm going to assume I'm in the clear.

ANy suggestions, or advice? Tim if you read this I'd love further explanation as to what damage this will actually cause,you were pretty direct and well informed when I was chatting to you, but due to lack of time I never got all the info.

[Fish]

Brett, I would have thought that nitriding would go deeper in to the metal than .001mm Thats just about taking the oil film off of it.

Dan

[Carl]

Hi all,
Alistair,Have you lapped side housings from any engine post 1978?ie 1st gen RX7? if so then you have played with Nitrided housings.
I ask this cos all side housings post 78 are nitrided.
I have built a few engines including FD ones with mildly LAPPED housings and had no probs.
The trick is not to go too far,and to LAP side plates, not surface grind cos surface ground plates are not smooth enough.
Regards
Carl

[t2rew]

carl, the side housings on my 13bt are worn. the book i have says front and rear housings have a distorsion limit of 0.0016 and a wear limit of 0.0039. does this meen i can take upto 0.0039 off. what is the difference between lapping and grinding and is this something a profesional engineering shop would have no problem doing. can ds engineering do it.

[Carl]

I can get them done for you for £100.00 but will only be able to tell if the wear limit is ok by looking at them myself.If you are correct about wear limit then they should be ok.
Regards
Carl