I'm curious if anyone here has adjusted or has ever purchased an adustable regulator from Racing Beat. What shim thickness gives what psi? Is there a chart out there on the net?

I'm trying for 90psi. Do I need to shim the front too? I'm asking because my engine previously had a front stationary bearing failure. Only the rear reg was shimmed. Hmm...

I'm also curious about rotor and stationary bearing clearancing. How deep does normal clearancing cut into the copper? Also, polishing the eccentric shaft. Is it worth it?

Is clearancing ok, as long as the oil pressure is high enough to fill the gap? Is that why it's not recommended for street engines? Will 90psi be high enough with normal clearancing?

Thanks for reading, and if you know the answers, please don't hesitate post!

 

1/8" shim on the rear pressure regulator on pre 81's causes it to bypass @ 85psi.

You only need to shim the front pressure regulator if you're running the race 110-115psi rear regulator.

normal clearancing will not cut into the copper. it is still in the shiny bearing babbit material. Polishing the eshaft doesn't take much time but it does make it more slippery.

Mmmmmmmm clearancing.......... You want just enough clearancing. Too much clearance without the race oil pressure regulator, oil pump, and oil galley enlargement will really lower your oil pressure.

-bp-

 

Micropolish the eshaft, and use an oil additive like MMO, or figure to switch to synthetic after a few thou breakin miles. High pressure can help by reducing oil temp, but I don't think it increases oil bearing strength. Maybe you sprout leaks, too. Oil cooling is more important, IMO.

In my racing days we found that big aluminum finned sumps worked better than open clearances. Really, you open the clearance to obviate a statistical tight clearance, rather than to make all clearances open.

B


B

 

1/8th? I've got two pre '81 pressure regulators. One has an old corner seal ground down to 4.1mm and the other has a lock washer that's 1.75mm in the thin part, and 3.25mm in the seperated part.

Hmm, it would be like a progressive pressure regulator because the lock washer is easier to compress than the big spring. Anyway, it's about half as thick as 1/8th of an inch, so I think I'll go with my 4.1mm shim because it's closer to the psi I want being 0.1615inch to be exact (I love this digital caliper, hehe). Since it's a little over 1/8th inch, it ought to come out close to 90psi, I'm guessin'.

Maybe I could try the other 'shim' (lock washer) in the front because it's so thin and would still keep the front bypass close to stock. Both these engines had failed front bearings with rear pressure shims, so what have I got to loose? Don't most bearing failures happen on the rear bearings? Hmm...

I'm also going to use a 17.5mm, the so-called 'high volume' oil pump. No doubt about that. My 12A had a 15mm pump which got scored pretty badly. Everything's been cleaned really well to remove any little bits of bearing material that may have remained in the oil galleys.

The reason why I asked about clearancing is because I was just hoping that worn bearings could be reused if the amount of missing babbit material matches the amount removed in clearancing, and Yaw's pics show lots of copper.

These pictures are Paul Yaw's work so I'm not going to post them on this forum, just the links. The clearanced rotors show some copper...

http://personal.riverusers.com/~yawpower/pic6.html
http://personal.riverusers.com/~yawpower/pic7.html
http://personal.riverusers.com/~yawpower/pic9.html
http://personal.riverusers.com/~yawpower/pic16.html

For explanations of each pic, here is the main page: http://personal.riverusers.com/~yawpower/picture.html

My old 12A will be going into a baja bug. I plan to thrash on it hard. My thinking is to not bother with new stuff if there's this great a chance it'll get cooked anyway. Everything is used and within '76 spec (it's going to be a '73 12A with '83 rotors) except for the bearings. I want clearances to be large enough to be able to pass sand through the bearings if need be. Wouldn't that be a neat trick?

Anyway, those old engines have hard side housings with extra thick iron castings. The only thing better are the nitrided housings because they're harder and lighter but still as strong. The newer apex seals of my '83 rotors WILL wear on the chrome faster than the stock 6mm seals would, but this engine has failed a grand total of at least three times. First as an RX-2 engine, then twice in an MG Midget. Now hopefully some intelligent building principles will be implimented and allow this engine to last a long time. Enough oil/water cooling is the key here, which was lacking in the MG.

Thanks for your reply and please let me know what you think about my ideas. Thanks!

 

bliffle, there's some surface rust on the e-shaft that needs to be dealt with. I've got some 1500 grit wet or dry sandpaper and some metal polish. Should I go for it?

The '83-'85 12A that my rotating assembly came out of was overheated, but it wasn't locked up. The bottom of the water jacket had filled with some radiator sealant and allowed the side plates to turn blue and the rotor housings got crushed. The rotor gears (and the other sides) have a little side rubbing evidence so I tapped them back in. Now they're within '76 spec. Like 69.something compared to the '73 rotor housings' 70.0-69.94 (up to .06 I think is what the spec called for).

The only thing I'm concerned with are the '83 bearings. They're missing some babbit material, but the engine never locked up. And it was totally stock in every way as far as I could tell other than maybe the apex seals (they look almost like Atkins' seals because of the side piece seals looking different than what I remember) and the 17.5mm oil pump (I'm not sure if these came stock on this year 12A).

I figured I could go with upped oil pressure since the '83 bearings never locked up, but probably could use a little extra cushioning.

 

remember, those race clearanced rotors are for racecars with the 115psi pressure regulator and many other lubrication upgrades. for the baja bug carefully measure bearing clearance, make sure it's within spec.

pass sand thru bearing clearances, that's funny

I think you should go for polishing that e-shaft. just take off as little as possible.

Would you be interested in buying an intermediate and front plate that are J-Bridgeported and need lapping?

-bp-

 

Ok. Hmm, that sounds like I'll need to shim the front regulator at least 1/16th", and the rear can keep on using the 4.1mm shim (don't you just love me using two different measuring methods on the same engine as if they were chocolate and vanilla in the same cone? ).

My reasoning is that the bearings are used and probably already worn out, yet the engine they came out of failed because of radiator sealant crap, not bearing related at all. Even the rotor housings had minimal chrome flaking. Too bad they're crushed.

Heh, the water pump housing had gobs of silicone all around the pump sealing surface because the previous owner didn't use a gasket (there was a chunk of silicone blocking one of the coolant passages).

Most people believe in life, if some is good, then more is better. Well, that's not always true. But I think I can bend the rules a bit and up the oil pressure so I can keep using these old bearings, copper showing and all, and if the engine runs for a year and only costs me $135-$150 in gaskets, man, that's worth it! The time spent cleaning, inspecting and rebuilding is worth it, in my opinion. Like a practice engine, since I've never rebuilt a rotary before.

Cool, I'll polish the e-shaft so the rusty part is smooth, but I'll have to leave the pitting alone. too bad I couldn't sand down into it and fill it with bondo, eh?

Sorry, no need for side housings right now. How long do you plan to keep them? My friend will be rebuilding an old school 4 port 13B for his REPU soon. I'll ask him if he's interested.

 

Wow...Im lost in this convo...I understand small parts, but its a little more hardcore than I know...

~T.J.

 

About that silicone gasket sealer: bad stuff! I've had other engines that failed 'cause the damn stuff squeezed into an oil passage or water passage. The gasket should seal, you put a little heavy lube (we always used chassis grease), which lets the gasket wiggle around a little while it's getting comfy, and if any goes in a passage it washes away.

B

 

I tend to get long winded. Actually, this is the first day this year I've had enough time to post this much.

Well let's see... basically, I'm building a '73 12A for my baja and I'll use '83 rotors which have somewhat worn bearings. Same with the stationary gear bearings. I'll be upgrading the oil pump to a high volume unit (17.5mm) and shimming the front and rear pressure regulators to keep the bearings filled with oil.

The '83 12A the rotors came from wasn't locked up, just high mileage and it overheated. All the parts are within 1976 spec, other than the bearings, which means I can abuse this engine and rebuild it as needed. I've got no problem spending $130-$150 on gaskets and O rings if it means I can have a running engine.

I'm just testing the waters here to see what people thought of my wacky engine project. That's the gist of it.

 

That's good advice bliffle.

 

Two questions or concerns:

One, I believe it is the 79 and older oil regulators that you can shime. I thought those made after 80 were "sealed."

Two, in the swap of parts are suggesting are you still keeping matching flywheels and fronter counter balance together? These two parts should remain as a set. And, as I understand, the rotors, eccentric shaft, flywheel, and counter balance should be kept together, since they are balaced (to a greater or lessor degree) at Mazda?

best of luck

 

It's either '81 and older, or '78 and older that had the easily adjustable regulators. All I know is I've got two.

I'll be using an '83-'85 rear counterweight and aftermarket flywheel. The rest are all the same so I hope they'll be a balanced assembly.

 

PRE-81 can be shimmed to bypass @ 85psi. Best of luck jeff, let us know how it goes.

 

Cool, I will.

I may be getting an ACVW (air cooled Volkswagen) 1600 for it in a week or two to get it running. Then, after drivability issues are solved, and I've got some money to spend, I'll take the rotary plunge.