ian65

I have a couple of spare engines and thought I would have a go at porting one of them. I've got loads of experience rebuilding piston engines but have never taken a rotary apart before.
I've done loads of searches and watched the rebuild vids but none seem to answer my question which is:
If I take apart a known good engine just to open up the ports, which seals do I need to replace.... just the O rings sealing the engine plates together? or will I end up needing a load of seals once I break open the engine. I'm assuming the rotor seals and apex seals etc are all good.
What do you reckon?

74RX4

iTrader: (10)

You may be able to just replace all the o-rings. Once you take the engine apart you may as well replace the springs for the metal seals. They are pretty cheap.


http://www.rotaryaviation.com/o-ring_kits.htm
http://www.mazdatrix.com/b2.htm

rxtasy3

iTrader: (2)

if the engine starts fine, hot or cold, then all the metal seal will probably all still be within spec. so theoretically all u'd need is the o rings to reseal the block. but remember, just like with piston engines, everything has a wear pattern on them so everything needs to go back where it came from. so lable ALL seals and springs. but keep in mind, just cause it's a decent running engine doesn't mean once u break it open, there could be some chrome flaking in the rotor housings that will make them un-reusable. depending on the amount of step wear on the imtermediate housings, those might have to be machined. mic the apex and corner seals to make sure they're within spec. if any r out of spec, just replace them all. the first time i built my engine i reused all internal seals. after getting it back up and running, i had hot start issues. second build went with all new and eliminated that problem.

j9fd3s

iTrader: (3)

i'd pull it apart and measure everything, and that'll tell you what to replace. it takes a little longer, but it does remove the guesswork while delivering a tighter engine, and its cheaper too because you only replace whats needed

Keith13b

iTrader: (6)

First off, think really hard about your question............

Secondly, if it were my engine, I would buy a complete soft seal kit for a port job. Why tear it apart and re-use seals that are old and compressed; plus there is no guarantee that you wont tear a seal upon disassembly. Nothing sucks worse than having to order a seal or two and wait for it to be shipped while your engine is apart! Plus the peace of mind knowing the seals are all new.

Lastly, think really hard about your question again, considering your experience with rotaries. I'd try to find a forum member or a local person who can provide some guidance. Especially the organizing and labeling of the hard seals. If you are stuck going solo, so be it, but go slow and read, read, read.

Good luck.

ian65

Thanks for all the good advice above guys.
I'm going to do this myself. I've been rebuilding engines for years and I'm confident that I'll be able to sort this engine.... and if not, well it's only a spare engine!
I don't really want to get into the expense of a full rebuild kit but take your points about old seals etc.

DivinDriver

iTrader: (15)

Housing o-rings, dowel pin o-rings, front cover gasket and o-ring, oil pan gasket and tension bolt seals are pretty much the absolute minimum.

The housing o-rings are the most expensive rubber bands you'll ever buy.

If you've got the money, replacing the main seals and the oil-control ring o-rings will save you re-work time later.

Everything else depends on measurement of wear.

Unlike a piston engine where you can pull heads and do a top-end rebuild without disturbing the bottom end, you really can't take a rotary "partway" apart. You can pull the front cover and get to the oil pump & front stack without disturbing the 'keg," but once you open the keg it's got to come all apart anyway before you can reassemble.

They're simpler than piston motors, but you need to make very sure each seal goes back in the specific slot it comes out of, and tolerances are in many ways tighter than for a piston motor.

Twilightoptics

iTrader: (1)

Contact Pineapple Racing. Rob will set you up with what you need. I recently just asked him about taking apart a perfrectly good motor for porting, and he said it's no problem just use new softseals in all cases. So that's Seals/O-rings/Oil Rings etc. You don't need to replace the side/apex hard seals. As above, just make sure you put the hard seals back where they came out.

Keith13b

iTrader: (6)

A soft seal kit will run in the $300 range. If you can't afford that, you shouldn't be cracking that motor to beginn with.

ian65

I said I didn't want to go to the expense of a full rebuild kit..... I'm quite happy to buy the soft seals if that's all that's required.
I was asking for advice on what to replace not on what I can afford.

Keeble

iTrader: (3)

go to atkins rotary and buy this N201-89-100. thats is all orings and gaskets for a 12a. everything else from there is optional, but might i suggest replacing the oil control o-rings (ARE15-13B) and front and rear main seals (ARE81).

now that is a bare minimum. for the pure fact that they don't cost much at all, i would replace the side seal springs and the corner seal spring (3rd gen style).

Also as a note, as far as the little rubber plugs in the corner seals, they are not necessary, you can throw them in the trash and you could put new ones in but like i said, its not necessary

Keith13b

iTrader: (6)

I hope my previous post didn't come across the wrong way. I was merely stating a factual opinion, sorry if it sounded sarcastic. That was not my intention. I was a little taken by the fact that others were telling you very specifically what seals to replace when in reality they all need replacing. I would just buy a complete soft seal kit and would advise against "piece mealing" the seals that are bad or broken. Your hard seals should be fine and those are the expensive parts, so you should be good to go. Just make sure to check them when they are out to see if they are in spec. Thats the time consuming part, but worth checking while the motor is apart.

Good luck and post back with your results. Also - whose porting templates are you going to use and what kind of porting are you aiming for (SP, BP, etc)?

Good luck. I remember my first rebuild was a street port 12A using RB templates. I had no major issues and the motor ran strong as hell using the nikki carb. I was hooked. I'm sure you will be too.

ian65

cheers Keith,
thanks for your advice.... that's just what I was after actually. I thought, somewhat naively, that I could get away with just using new O rings but after reading your post plus the advice from the other guys above, I realise that a complete soft seal kit is the way to go.
Thaks to everyone who has offered advice re this post....
when I get started on it, I'll post up the pictures...
I'm undecided what porting template to go for at the moment.... probably a street port or a bridge.
The main reason for doing it is that I want to learn how to do it and how the engines come apart and go back together. It's all well and good watching videos and reading books about it but you really need to get stuck in and do it yourself to fully understand it.
I need to finish my turbo intallation on my road car first though...