SpeedOfLife

iTrader: (16)

I picked up a 13bt short block from a local guy who pulled it from his '87 TII at ~105k miles. It had not blown and apparently never overheated. The pics are after being hot tanked at Arnold Motor Supply. I forgot to mention that the rotor bearings are Al so I will now have to replace those. Aside from those bearings I'd like your thoughts on the longevity/strength/quality of a rebuild I might expect if I reuse all these major components. The irons are extremely flat according to the machinist, but he brought my attention to the grooves the corner seals created, which to my guessing might be 1-2 thousandths of an inch deep. I don't know how critical that can be. mmmm, Pringles. I really needed some food... Anyway, the housings are my biggest concern. They both have some chrome flaking, mostly on the side with the triangle seal piece, and if I rebuild with two piece seals I could put the triangles on the opposing side. It looks to be about 2mm from the side, and for the most part not real deep into the chrome (not all the way through). You should be able to see at least some detail in the pics.

I would like to rebuild with new one or two piece Mazda apex seals as well as all new rotor seals w/ FD corner seal springs. It seemed when I was removing the side seals that two or three were moderately stuck with carbon and one side seal broke (though I still got everything out). I will, of course, use new soft seals and I'm really not sure what else I need for rubber gaskets and such.

I also want to port the motor, but I'm not sure what exactly I want yet. I'd like something streetable, turbocharged with the stock turbo for a while at least, but if possible on the stock turbo eventually make up to 300hp (if not possible on the stock turbo, I at least want to build it so that it could support that if I had a different turbo setup for the future). Despite being daily driven though, this car WILL be tracked as often as I can manage. My turbocharger is in pretty good condition considering its age and the general neglect the rest of the car has gone through. There's almost no shaft play at all and I hit boost pretty quickly. Also, a smooth idle isn't a top priority nor is excellent gas mileage, but it'd be nice if I could hit 16/20 mpg if I tread softly. As it is now, driving fairly hard around town I tend to get 13-15mpg, usually about 17-19 highway. That may be somewhat beyond the immediate issues here... Going on.

Additionally, for which I'm still pretty pissed at myself, I accidentally dropped a rotor a couple inches. It slid out of a housing to concrete as I was moving it along the floor. I'll post pics of that, too. If I had to guess, I'd say it'll work fine. The apex corner was unaffected, the hit just barely took the edge off a portion of where the face meets the side, BUT I would like some professional advice just to be sure.

The rust concerns me a little, but I figure I can use a wire brush on my dremel and maybe a brush on my 4.5" angle grinder for the heavier surface rust. I know I'll have to get rid of the Aluminum oxidation, too, especially if I want to powdercoat, which I want to look into. I hear Kevin Landers does it, but I'm not going to dump money into these housings if they won't be used and I also don't know how much it would cost to have the motor coated. I also want to know if I'd be better off breaking off that one vacuum or coolant nipple and tapping in a new fitting. It's in fairly rough shape and I know from experience how thin and weak those things can be...

In all this, I'd really appreciate input from people with build experience. Like I said, my main concern are the housings and I want to know what I might expect from reusing these particular housings.

Thank you in advance, this build is really important to me. My current motor has ~85psi compression and I want to get this build right so it will last a while and I can have great fun with it in the process.

http://img228.imageshack.us/img228/318/p7160010pl4.jpg
http://img340.imageshack.us/img340/91/p7200040xk5.jpg
http://img156.imageshack.us/img156/6996/p7200041oz7.jpg
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http://img102.imageshack.us/img102/5945/p7200049xr1.jpg
http://img148.imageshack.us/img148/1589/p7200050al6.jpg
http://img339.imageshack.us/img339/4241/p7200051px1.jpg
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http://img206.imageshack.us/img206/3788/p7200058kg1.jpg
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http://img113.imageshack.us/img113/1031/p7200063ag6.jpg

edit: Btw I just got these back from the shop today and I think they were pulled from the tank a few hours before I took the pics. They were definitely dry and cool, I know that much. Also, only the housings, irons, and rotors were hot tanked, nothing else.

RotaryResurrection

iTrader: (8)

everything looks fine based on what moderate amount you can tell from pics alone. The rotorhousings have moderate wear and are reuseable but will not make a "like new" engine. They will make a strong engine, however.

Rotors are more sensitive than you think...they look like massive chunks of metal that are indestructible, but they are actually EASY to damage. Check all seal slots adjacent to wherever you dropped the one to see that they still move freely without binding.

FelixIsGod29X

iTrader: (50)

Look into bnr turbos, they sound like the perfect choice for you.

SpeedOfLife

iTrader: (16)

I know rotors are very sensitive, that's why I just about rocked my face on the ground in anger after dropping it. I'll check the seal slots like you said, but if they are binding a little couldn't I gently file out whatever crap is where it shouldn't be?

And I understand rebuilds simply can't be like new unless all the parts are like new (or are new). I'd be pretty happy if I could get at least 40k miles out of this motor at the power I want. Any experiences with the longevity of such a build?

SpeedOfLife

iTrader: (16)

Also, I'd like to stick with the stock turbo for now. If I can't reach 300hp with it then eventually I will upgrade, but turbos are very expensive and the current one will do for the time being.

FelixIsGod29X

iTrader: (50)

A bnr turbo is a hybird turbo, as in it mounts to the stock manifold and can retain the top mount intercooler untill you reach a certain point. Good luck on 300hp on the stocker, i dont recall what they max out at. -nick

RETed

I dunno why you insist on doing this...
By flipping the triangle assist piece on the other side, you 1) just created a void for which more compression is lost, and 2) start digging a new groove when the new apex seals start rotating.
Keep the triangle assist piece on the same side.
It will eventually mold into the groove, and you'd get a little better compression.


I don't think Mazda ever made one-piece apex seals short of the racing stuff.
One piece apex seals are not recommended for street use, since they seal less than multi-piece apex seals (i.e. less compression).

The broken side seal is a blessing in disguise.
You need it to "clean" all the side seal grooves.
See Rotary Resurrection thread / page on rebuild info.


Slide a side seal with a little bit of oil on it.
It should slide easily without getting caught.
If the side seal jams in the slot, the rotor is no good.


-Ted

RETed

I tried to get a good look at the rotor bearings, but you don't have good pics of those.
What little of the bearings I could see from your pics, they look okay.
There's a few pics where it looks like there's a wear groove in there, but it might just be the lighting.

As long as no copper is showing and there are no grooves that can catch your fingernail, you should not be changing those bearings.
Hot tanking and solvent dipping should NOT affect the bearings.
Only acid baths can **** them up.
The bearings are copper base with a lead / indium (guessing here, but this is typical composition) coating, and they are impervious to hot liquids and solvents.
Going with new bearings is a PITA.


-Ted

SpeedOfLife

iTrader: (16)

Yeah, there's a small wear groove showing about 1/4" of copper on both, and the stat gear bearings, too. There certainly are no grooves I can catch a nail in though, they're quite smooth. Maybe I'll ask that machinist if he used any acid on them.

Thanks for your responses so far, this is great info.

vrracing

iTrader: (1)

In

http://img156.imageshack.us/img156/9766/p7200042cj8.jpg

the flaking runs all along the back edge of the housing, correct? What I see is a dark grey area and then what looks like chipped metal. Am I seeing that right?

If my interpretation of the picture is correct, then it is the width of the flaking we care about, not so much the how far around the circumference of the housing. Correct?

Thanks