Unevolved

This is as much a plea for advice as it is an introduction, so bear with me.



First off, about me. I'm a junior engineering major at Texas A&M University, but over the summer, I'm a technician for Texas World Speedway building Spec Miatas for the driving school. I drive a 7thgen Civic (the redheaded bastard stepchild of the Honda tuning family) for a daily. Until this weekend, I had zero experience with rotaries and/or carburetors.



A while back, under its previous ownership, the Speedway purchased an '85 FB for unknown purposes, along with a 13BT and transmission on a pallet. The car sat unmolested in 95% original condition until this weekend. I was offered a chance to purchase the car and spare engine/tranny for $1000. After a little bit of bartering, I wound up with the car for $500 and am puchasing the 13B at a later date when I actually need it, there's plenty of work to be done in the mean time.



This weekend, I dove into the car, expecting the worst. We towed her from her resting place into my shop, where she went up on the lift. I noticed a large amount of oil on the left side of the motor, and noticed it was missing the trailing plug on the front rotor. I was still hopeful, as there was fresh oil sprayed out, so maybe there was hope for the seals to not be completely gone. As per the advice of the Star Mazda team next door, I fogged the rotors with Marvel, and turned it over by hand first. She didn't want to at first, but finally turned over. There was not a hard "give" as if something broke, it just started to turn. I put in some fresh plugs, drained out the gas, put in some fresh gas and pumped the old gas out of the lines, and changed the oil. Charged up the battery, hit the starter, and nothing. She wouldn't catch.



Fast forward to last night. We keep trying various things to get her to run, but it appears the carb is just dumping fuel into the engine. All plugs are firing, but no luck. I would pull the plugs and they would smell like gas, so I know she's getting fuel. It just appears she's getting way too much. The lights are on, but nobody's home.



Results of a compression test indicate the rear rotor's fine, but the front rotor is completely dead. Me and my roommate pulled off the carb last night, very carefully, and are taking it apart, looking around, and trying to teach ourselves about it. I'm pretty much hoping we'll put it back together right following Mazda's repair manual and have better results than last time.



My current plans for this car aren't that ambitious, yet. Short term is to just get it running semi-reliably and autocross it. A lot. I plan to swap in the 13B and transmission, and retrofit the 12A's carburetor and just run that while I save up the money to rebuild and turbo that motor the right way. I don't want to half-*** a turbo build, and I'd rather wait and do it right.



Cliffs: Bought good condition FB for $500, won't run. Swapping in 13B and carb'ing while saving for rebuild/boost. Thoughts?

bigboi12A

Let me be the frist to welcome you to the world of rotaries. Umm,,, I don't think it is possiable to put a nikki carb on a efi low compression turbo motor. First off the intake manifolds dont match. Seconed I don't think the nikki flows enoufgh cfm's. Do you self a favor and 86 that idea. Swapping 13bt into the fb chasis has been done before and some one other than my self will be able to help you almost step by step. Me personally Im so hard-core 12a it isn't even funny. The 12a has a lot of potential. Overlap, half bridge, fullbridge, Ive had all these configuerations and they all rock. Whats your ultimate goal? How mutch money do you want to spend? How mutch time do you want to put into a project of this magnitude? Based on what you've said and what you've got. Heres my two cents. The 12A is cheaper to rebuild and in my experiences very very tough. She takes a lickin and keeps on tickin. Sell the 13bt motor. You'll get all your money back and then some. Maybe keep the tranny, Turbo II gear boxes are bullet proof. It might be a little overkill for autocross. I'm sure someone else will chime in on that one. The FB tranny has good gear ratios but its input and main shaft are small and weak. Modify the 12a, maybe even 12a turbo EFI? Destroy the competition with the smallest bullet there is. Thats what I get off on.





P.S. Hondas Are GAY!!!!!

Unevolved

Thanks for the advice, I'm still deciding what I'm going to do. Right now, the 12A has a dead rotor, and I'm not sure what condition the housing itself is in, even. I'm not sure selling the 13B is a viable option, given the circumstances. One of the motors is going to need to be rebuilt, and it makes sense with what I currently know to rebuild the 13B later on down the line and boost it. I've heard running the Nikki carb on the 13B isn't that big of a deal, just needs an adapter plate and some freeze plugs.



Thanks for the Honda comment, I've worked on Hondas often and thoroughly and my love for them is well-deserved. Good to see the stereotype about rotary guys comes from somewhere.

boyee

You will need a 12A or gsl-se front cover. then you install the distributor like it was meant to be.



screw the Mazdatrix injector kit. plug the injector holes in the middle iron with 16.4mm freeze plugs and take up way less space.



also you will need a GSL-SE oil pan.



this swap has been done many times so im sure you will find help when you need it.



good luck.



fyi, 12A housings are getting extremely hard to find N.O.S. if yours are good theres a company that does cermet coating. not sure about the results but its worth a try if you buy their concept

bigboi12A

Hold on You have a 13B turbo motor? Then you want to run it naturally aspirated, with a 12a carb, a motor thats supposed to have boost with no boost? I did not know that was possible. Due to the 8.5 to 1 compression ratio that is if were talkig turbo II block. I would guess that it run like crap. I still wana here from one of the group moderators on this subject. If it does work Cheers! Na man I didn't mean to rubb you the wrong way with the honda comment. There good street cars run well and for a long time. God that was hard to say. Im just rotary for life. Ive driven only rotary cars for a little more than a decade, since I got my license. If that makes me stereotypical than guilty as charged. How many miles are on the car? Theres a good chance that form sitting for a long time the apex seals have carbon build up and are stuck down in the rotor. I heard you when you said that yall poured some kinda oil in the motor to help eliminate carbon. Again form sitting some times moisture can cause rust deposits around the apex seals. Even though the the hood was shut and the air cleaner assembly is all there like its supposed to be. Just a guess. Take the motor apart, if its your first you'll have fun. Its possible to find used rotor housings in good condition, you just need to know what to look for, and where to look.

Unevolved

That's the current plan. I'm nixing the idea of carb'ing the 13B, I'm going to hold off on that. Hopefully before too much longer I can pull the motor out of the car and tear it apart and see exactly what I'm dealing with. Maybe even try some amateur porting.

bigboi12A

Centreal Auto parts sells just the gaskets for a tad more than a $100

bigboi12A

get some street port templates from some where. Dive in head first!!!!!

Unevolved

Thanks for the heads up, I didn't know those existed. That could be a huge help. What's the worst that could go wrong? The motor doesn't run now anyways.

bigboi12A

If you dont know what your doing it can get ugly. Do some research. Um Mazdatrix sells a porting vid. Crall before you can walk. Atkins rotay sells some good vids. Your car is clean judging by the pics you took. Maybe just do the rebuild no porting. Throw a small holley with a racing beat intake. or the webber down draft with the racingbeat intake. For sure throw a headder loose the cats and I love racinbeat mufflers awesome sound and performance. Msd's are a giant rip off in my opinion. Summit has there own brand of ignition boxes. There digital and have built in rev-limmiters. adjustable fom 500-12000. There cheap also like a $130 each. They work good I have 2 in my street car and 2 in my race car. finally I would change the gears in the rear to top it all off. What Im getting at is enjoy the car dont over complicate things.