spartiatis

i've also sent it by mistake to another forum.
i'm on the rebuilding procedure of a s5 13bt.actually,i'm on the parts cleaning and is very tough cause it's full of carbon deposits.
there are some issues i need to make sure before i go on.
1.i already got the street-porting templates from mazdatrix.do you think that those templates will be proper porting guide for turbo applications?
2.do i have to grind both primary and secondary inlet ports at equal size?
3.what is the phase(or angle) difference between the two rotors?
i mean that if i put the front rotor(while engine assembly) with the one apex to 12 o' clock on rotor housing,what should be the position of the rear rotor?

rxtasy3

iTrader: (2)

Front rotor pointing up, rear rotor pointing down. I think u should match the inlet side of the ports with the hole sizes in the gasket, and with the intake. As for using it for turbo applications, I don't see why not.

spartiatis

as i can understand there is a 180 degrees angle between the two rotors.but,what about the crank's position?does it mind or not?
i did not understand what do you mean matching ports with gasket.
thanks,anyway

peejay

The e-shaft can only go in one way, determined by where you have the front rotor positioned. When you put the rear rotor on, it can only go on one way determined by where the E-shaft is. No voodoo.

rxtasy3

iTrader: (2)

If the intake holes in the gasket r bigger than the actual ports r, lay the gasket up there, scribe or trace the hole size and grind to the line. Can someone draw him a picture.

peejay

It's better if the ports in the engine are bigger than the ports in the intake manifold. In other words DO NOT GASKET MATCH unless the intake manifold port is bigger than the engine port.

The step helps prevent reversion by acting like a one-way check valve.

spartiatis

I 've tried and managed to put the rear rotor in many different possitions with no need to change the e-shaft's position.should it be bad news.such as worn rotor bearing?
i've also noticed damage(something like cracked and missing pieces) in the front housing where the water seals goes.is it possible to fix it with jb-weld or something?

spartiatis

there 's no need for a picture.i 've just confused cause my question was if i have to grind equally those primary and secondary ports inside the combustion chamber.
watch the photo.

rxseven

You are confused as to how the engine works. The crank does not rotate at the same rate as the rotors. The shaft turns 3 times faster. As for the damage to the water seal groove, it is critical that you do it right or you will tear it down again. if it is in the inner seal area, jb weld probably won't work.

spartiatis

i was only confused about the position of the rotors in relationship with the e-shaft's.now, i think, i have it clear in my mind.
you guessed right.it's in the inner section.i propably have to buy a new front housing.any place for a used one in good condition?

Project84

The front rotor is 60 degrees ahead of the rear rotor as far as timing. But as mentioned above, if you sit the front rotor on the e-shaft with an apex at 12 o'clock position, the rear will have an apex at the 6 o'clock position. The rotor journal is round, and the hole in the center of the rotor is round, so the rotor will spin on the shaft, but the trochiod shape of the rotor housing causes the rotors to line up one way, and one way only, and that is the way we mentioned. So when you go to put the motor back together, the rotor in the housing, and the shaft going through the center will line up properly. You may have to spin the one rotor and the shaft to get the second rotor to line up, but its normal. If both rotors are in the housings, then you got it right.

Here is some info from Mazdatrix web site about porting. You should use the port template for the type of port configuration your engine has. They have them for turbo and non turbo engines. As long as you follow that template (stay between the lines!) then you'll be fine.

peejay

If the water seal groove area is cracked, you need to replace that housing. No ifs, ands, or buts. It is officially scrap metal! Inspect the other two side housings thoroughly, as this is a known fault in the '86-up engines.

spartiatis

what does usually cause that kind of damage?
why don't you the older and more experienced on rotaries, guys create a thread that should help every newbie(like me) want to start a rebuilding on his own?
you know,tips and tricks,mods,links and many more.
i've seen many threads such as web pages relative to this but never all the info toghether.
that could help you to avoid the same questions all the time.
not sure if proffessional rebuilders will agree but i think that the one who wants to do it himself,he will do it one way or another.

i hope it haven' t done already and i never noticed.
then you have right to call me @#$!!%$

Project84

The water seal grooves crack because its weak. Its a defect in the manufactuering. I had an engine with this problem and I also talked to the people at Mazdatrix about it. They have a writeup on their web page about it.

Click here to see it, and see pictures.

Atkins Rotary has a video for sale that you can use to rebuild a motor. Its hard to do an accurate write up on something as involved as rebuilding a motor. I tried to do a write up that would be an all encompassing answer to one of the vaguest questions I've seen: "I just bought a RX-7, how do I make it faster?" Usually asked by people who don't know a thing about rotary engines. This is a very vague quesion cause so much is involved. I started my write up, and 3 hours later, when I was finally almost finished, my computer froze up and I lost the whole thing. I was pissed. You can buy a Haynes manual and it has a complete tear down and rebuild with pictures. Since most people have that book, there isn't really a need for a thread to say how to rebuild an engine. Most people don't ask for, or expect to get that kinda info on here. If you don't have the tools or skills, then something like the book or video, or both are a must, not an internet write up. Plus, you would see that different people have different ways of doing stuff, and everyone would be throwing their 2 cents in making it confusing.

Here is a link to a site that has an overview of a teardown and a rebuild. It has other Rotary and rx-7 info too.

Good luck and keep the questions coming.

spartiatis

thanks for all the info.i 've already ordered atkins video and haynes manual.but i still haven't received them.as far as i don't know if those things will answer to my questions,i became a little anxious and opened this thread.
you are right that it's difficult to cover such a difficult issue like rebuilding,in a few pages of a thread.i meant that you may post some helpful tips that possibly won't
included on the books and should make our life easier.

Project84

Cool, here is a tip. When you put the apex seals back in, you can use locktite, or superglue to put the triangle corner piece on the upper apex seal. Don't glue the lower apex seal to the upper seal. If you have 2 piece apex seals, then you don't have the upper and lower halves to worry about like with the 3 peice seals.

Also, you can use hylomar to glue the water seals into the grooves so they don't move. I don't know if the video mentions those points, but I know the Haynes book doesn't. Other than that , I can't think of anything. Take your time, don't force the peices together, and keep a clean organized work space. Its way simpler than with a piston engine.

Oh, and read this page. It has good pics of the parts under the front cover and will illustrate how to keep them from moving until you get all the parts together. You don't want these to move because their is some bearings and spacers that will get disslodged if they move too far.

Good luck with the rebuild

spartiatis

questions are back.i noticed your advice to stay in the lines of mazdatrix template while porting.but i never got an answer for porting the primaries on the intermediate housing.do you think it's ok to make them as large as the template shows or i have to use the tempate only for the secondaries(side housings) porting?

Project84

There is a port template for the intermediate housing. Thats the one you are supposed to use. And the stock center port on the turbo is bigger than the stock center port on the N/A, so be sure you order the right kit or you could get a template that is the wrong size and it would lead you to cut the wrong part.

rxrotary2_7

please go into further explination.

Project84

It starts getting complicated when you get into the way the air pulsates through an intake manifold and how the legnth of the intake runners effect the pulses, which in turn can alter the engine performance during low or high RPMs.

Project84

Read through this thread and it will help explain a little better.

https://www.rx7club.com/forum/showth...light=harmonic

Update: (so I don't appear to be a post *****) Read this thread too. It has a very good explaination as to what he was talking about.

https://www.rx7club.com/forum/showth...=port+matching

spartiatis

i think that if after porting, primary ports are still smaller than sencondary ones(also ported) you have a street-port setup.if you match the primaries to the secondaries size,that means that all four ports are of same size,then you've got an extended street-port.could it be right?

something more important.the rear rotor of my 13b has lines(grooves) all over it's width close to and towards to apex seals.this kind of damaged is shown on all three apexes.there is also a missing piece(leaving a hole) on one combustion surface(close to compression groove) about 1mm deep and 3mm wide.do you think that this rotor is for the trash can?

p.s.where i'm talking about ports and i mean the triangular ports inside the engine.not the inlet ports where the manifold goes.

rxseven

Port the primaries as far as you can go without getting into the waterjacket. Bigger the ports the better! You don't need to get radical with the exhaust ports though.

Project84

ok. The rotor is probably no good. If you have pictures, that would better help determine, but from what you are discribing, I would not use it again. I would especially want to see the hole that you say a piece is missing from. The only holes are supposed to be where the corner seals go. Some times the rubber inserts wear away, but that is nothing to be concerned about. But you said it was in the compression surface near the compression groove. Most people car that the bathtub. Besides for the apex seals, side seals, corner seals, and oil seals, and all the associated springs, and rotor bearing, nothing should come off the rotor cause its one solid piece.


As far as the porting info, some people port the manifold to match the holes in the intake, but you should only do this if the internal engine ports will be larger than the manifold outlet port, as Peejay was saying.

Project84

Here is a picture of the rotor combustion surface. From reading what you wrote, the areas in red is where the scratches are, and also where the hole is. The area in blue is what you call the combustion groove? That is whats known as the bathtub.

Did the rotor housing have the same grooves worn into it as the rotor?

You buying a new rotor or you looking for a good used one? I have a 87 13B rotor I could sell you for $75 (that includes shipping). PM me if you are interested.