Joel07

Ok guys, first off, this is my first post here. I've got an 80 RX7 that I've had for a little over a year and was my daily driver up until a few months ago. The interior is really gone to crap, the driver's side window busted (why I really quit driving it), and the rust is slowly eating it's way up the quarter panels (up that is, it's already through ). I really loved the car, and it's my first rotary car, but it definetly won't be my last. I'm thinking about pulling the motor since it still runs good and using it in another project I've been wanting to do: a dune buggy.

Now I'm not totally sure that it needs a total rebuild. I know it leaks oil (I'm not sure where from), and the tailpipe stays rusty all the time, which kinda scares me. Don't bash me too hard now, I'm a newbie, but if the rotor housing seals are starting to go, will this let water inside the motor? It runs good, although I'm suspecting the stock carb is gone to crap, because it has totally crappy throttle response, and doesn't start pulling until it hits about 5000 rpms...

Anyway, here's the plan. I'm gonna build a front engine dune buggy, and the rotary is perfect for two reasons. #1 is because I already have it, and #2 is because it's so compact. I've searched on the board and found a few useful threads and everybody says the motors are really not hard to rebuild. A few said that the Hayne's manuals are excellent to go by. Well, the Hayne's manual I have also has a whole lot of special guages and tools that they say to get from the Mazda dealership. How many of these do I really need? And do you guys think I really need to rebuild the whole thing? It doesn't smoke except a slight bit on startup every now and then. It ran strong, but the losing water thing just kinda scared me. It wasn't a lotta water, but I just don't like the rusty tailpipe. Other than that I was thinking of going to a street port, but now after looking at all that it entails, I might just stick with the stock ports and a Holley 4 barrel setup. Probably go with a Racing Beat header, and have to make a custom exhaust for the rest...

Hope I don't sound like too much of a noob...

erick1120

When I rebuilt mine I didn't use any of the gauges that that they said were specific to a Mazda dealership. You should be able to check for warpage with a straight edge and a feeler gauge and the other tolerances for the inside of the housings I would just take to a machine shop and have them check. I used rotor housing and rotors from another engine when I rebuilt mine so I new they were good before I started. All the tools that I needed I had or were easily accessible. If the coating on the inside of the rotor housings is worn really badly then you are going to need new housing whether the tolerances are good or not. If they look good inside I would check for warpage on the sides of them. I the seals are leaking, then most likely that is where the problem is. As for resurfacing the sides of the rotor housing I am not sure about. The front intermediate and rear housing you can have resurfaced if they are warped.

deeman111

ok i build my 12a's with just a socket set and a torque wrench. Go to your local rotary workshop and if the blokes are nice (like they are here) they will look at the housings etc and tell you if you need new ones. Its easier just to get someone who already has the tools to check them.

thats my 0.02

-James

Rx7carl

Hi and welcome to the board. Well before you pull the engine, a compression test can tell you alot. Also if you can borrow a coolant pressure tester, you can pressurize the system and see if theres any leakage. Bad water jacket seals will let coolant into the combustion chamber. You need to narrow down the oil leak, some are an easy fix, some require a teardown. Do a search here for leak of death or dowel pin o-ring leaks. If after all this you still need to rebuild it, a caliper (a good one), feeler gauges and assorted hand tools are whats basically required.

Theres plenty of resources out there on the net to help you determine whether things like rotor housings are re-useable or not. www.mazdatrix.com has an FAQ page, check it out.

Joel07

Thanks guys. I work in a machine shop so the machining part is easy. I've just never been into a rotary before. I'm trying to get in touch with a guy here who has a 13B-turbo in an old Corolla that drag races, and he did his own motor, so hopefully he can help me out. Thanks again, and this board is awesome! I've been learning more about RX7's the past week than I have my whole life!

slashdawg00110

Keep us advised on your progress. I'm thinking about trying a rebuild myself. The only motor I ever rebuilt was a 2-cycle lawnmower engine in jr high. I don't know how I did it, but my partner and I ended up with a seized piston. Somehow a needle bearing ended up in the cylinder.

Joel07

One more question, is the procedure for checking compression just like checking on a piston engine? I haven't even been able to get the car cranked the last two times I went out there. It doesn't do good to let a car sit like that. I'm still suspecting the carb, but it could be a more serious problem...

wwilliam54

oh yeah dont forget a haynes manual

Steve Shulz

Compression check the same as a boinger. Your looking for 80 psi or higher on all three faces both rotors. They will run lower but from what Ive read and experienced anything lower than 80 is looking to be rebuilt. But you can always run to failure just have your cell phone and a coat and credit card for the tow, cause it will happen on the worst road imaginable.