MG Sports Cars

Hope this goes ok Should be pics. Engine was installed in 1991 by myself . Been going strong ever since.

Welcome Steve, great look car! how much weight does the Rotary drop vs. a 4 cyl? What is your HP rating?

Hi Steve,
Could this be the car I took a couple of photos of in Watkins Glen last September......as I recall you had a spare rotor housing sitting on the air cleaner.
Welcome!

I think I remember seeing your car at NAMGBR's MG '92 in Peterborough, Ontario!

Correct?!

Thanks for sharing the photos Steve, glad you joined us!

Kelly the front weight was a problem I had rebuilt the front suspension the year before & put V8 bushings & new springs.The car sat with its noise in the air after the engine swap.At first I just ran 185X60X14 front & 195X60X14 rear which made ti presentable.This is how it was for its debut at John Twists summer party 1991.That year I got to go on the track at Gratton during there lunch break parade laps but the fasted parade laps I ever did Not like the Glenn.So yes Graham & yes Rick we where there.To get back to the front end.In the end I swapped in so not so new front springs & now run the 195 all round.I would think that the weight loss would be 200-300 pounds with the Mazda transmission factored in.The HP for the stock 12 A in the doner 1985 RX7 was 106 hp 106 torque I think.Its not as fast as people would expect but aroud 4000-6000 its fun.The photo if it shows up was last summer at a Time Attack day at Toronto Motorsport Park road circuit put on by CSCS

I will try again for the photo

Steve,

I got pointed over here from www.mgexperience.net they said that you did the same swap that I'm thinking about. 1985 12a (RX-7) in a 1978 MGB.

Questions:

Did you use the 5spd that came on the back of the 12a.... did the car have enough room in the tunnel for it?

Did you keep the stock rear end and ratio that came in the car, is it good enough or just good enough for now?

Any tricks with the engine and tranny mounts or just some brackets and welding?

What would you do the the good used 12a while it's hanging in mid air before sticking it in?

What did you do for a tach and speedo?

Thanks so much

Mike

Powell River B.C.
Canada

A couple of more photos of the roto-B in an earlier thread
[forum.britishv8.org]

Mike I did use the Mazda 5 speed which is slightly taller than the MG gearbox but I was able to cut a hole in the heater box floor as required for clearance & then redid the floor after.The engine mounts left front was a flat bar bolted to the air conditioner mounts & at the right height went 90 degrees & set on a mount which had a support plate welded on the frame rail upper ledge the right front uses the middle section of the original 12 A with a bracket welded at about 45 degrees and goes up & then 90 degree bend and hanges on the right frame rail mount. The rear trans mount is the MG rear cross member with a plate welded in the center to acept the Mazda orignal mount. With engine as far forward as possible the rear cross member bolted up to the car body in the holes used for an automatic trans.The biggest concern is the amount of front cross member that I removed and the brackets an braces added.The exhaust is always a problem it runs so hot when pushed.The exhaust I built is just a box unit and I would say that there must be a better way to do that.The car almost caught fire the first night out.The rubber on the foot well on the pass side was melting & later it burnt through the rubber pad that isolates the front cross member to the body so no interior & solid no the cross member Plus duct work down to the exhaust to cool it.The diff is the MG rear end and the gearing is very nice.4,000 rpm at about 70 mph in 5th

What can you tell me about the distributor and carb electrical?

What did you need to keep on the vacuum system? I see lots of vacuum lines and valves under the hood of these 2 mazdas that I'm going to be buying.



I'm a diesel equipment mechanic here on the west coast and I've never looked under the hood of an RX7 till tonight... small engine !!!

Mike, did you already see these two write-ups?
1) Brian Kraus's 1976 MG Midget with 1986 Mazda 13B rotary engine
2) Jonathan Lamson's 1960 MGA Twin Cam w/ Mazda 12A Rotary Engine

Mike for an intake just go with a proven set up like Race Beat with carb.The ignition can be done many ways.Always nice to see cars from the past on the forum I meet Brian with his midget at the Glen a coulpe of years ago The MG A rotary looks like an RX2 starter on top of engine

Steve,

I'm getting farther on my '85 rx7 12a into '78 MGB project. I've got the fuel and electrical sorted out now.

Are you running a speedo and how did you do it?

I'd be in debt to you forever if I could see some more pictures of your engine bay.

Mostly the firewall above the trans, a picture looking up at the bottom of the front engine mount area and last, how close the exhaust manifold ended up being to the frame.

If it's easier for you, and it would allow larger file size, to email them I'm sending you a private message to you with my address.

Thank you

Mike

Mike for the speedo I used the bottom half of the RX cable into the trans & the upper half is the MG cable remove the inner cables from both.Cut the outer cable for the MG in the engine bay around the brake master.Now take the RX inner cable and insert it into the MG speedo end lay the RX cable beside it now & cut it to the right length.Too long is better you can always cut twice.Now reinsert the RX inner cable back in the trans end.At this time make sure you have enough inner cable sticking out both end.Once that is right I took a 2-3 inch length of hose and 2 gear clamps to rejoin the two outer cables.Two notes grease or seal the connection.I got water in mine over time from washing engine bay & rust got in & seized & broke the inner cable.The inner end to the speedo may require putting in a vise & sqeeze slightly to make it a bit tighter in the MG speedo head.Now I dont know if your speedo is miles or km.Mine is miles & if I double what ever it reads & call it km it is fairly close.60mph on the speedo is 120km.Mike I will try soon to get more pics & from 1991 when i detailed the build but they are all just 35mm pics.I am buying a scanner soon so there will be lots of pics.The exhaust is only 1 inch clearance as I mentioned before that area would be better done different than mine.

Steve, it's good to hear that the inner mazda speedo cable can be made to fit the MGB, that makes things easier.

From that one picture there it looks like you had to cut a bunch out of the front cross member that's behind the steering rack?
I'll be dangling the 12a in there latter this week to see for myself I guess. I had wanted to keep the stock exhaust manifold but that might be wishful thinking.

Good to see the 12a runs well with all the vacuum stuff removed from the Nikki. Any inside tips on any of the vac valves I should keep?

Mike Kaban

Mike As I said before you should look for an aftermarket intake & carb I meshed with mine for a long time & now run a 79 carb on the 85 manifold.When I built it I wanted the RX 7 air cleaner in there so people knew what it was.LOL