Hmm. A bridgeport needs an open free flowing exhuast to perform decently. Pretty much anything from Racing Beat should perform well enough I'd think.

The exhaust on my MG is very loud. It has a very short primary header and a 22" long glasspack from Rotary Performance (they're out of bussiness) and a dual Monza tip tail pipe. Here's a pic:

 

The tip is hanging down because the hanger was not connected on that side. Anyway, the exhaust is probably louder than what you're after.

 

Or maybe it was Rotary Engineering that's no longer in bussiness? Well whatever the name, the rotary glasspacks are no longer available. (they do work and last a long time)

 

OK. I am using old pre 73 rotor housings in my 12a. I had several problems with using them with other plates. I am not exactly sure what plates i have in the motor (i have a lot of parts from repu, rx7 etc.). I just cant remember which ones i grabbed. Any ways, ya i get the motor all assemblled and ready to drop the tension bolts in. All go in except the 2. They went through the back plate of course but then did not line up with the holes in the AL housings. So what i did was just jack the engine back appart and lay the rotor housing on top of the center plate that i was using and put the dowls in so that it was exactly perfect. Once you do this you can see how they dont line up. What i did to solve the problem was just to convert the pre 83 housings to be able to except the newer plates. I just threw the center plate with the housing and the dowels on the drill press and just used the plate as a template. I drilled through the plate (stock locations of where the tension bolts go) and into the housing. I think i used a 1/2 inch long drill bit. It barely enlarged the hole on the plate, just enouph to make it not walk around. A long end mill would work best, but the drill press did the job. I actualy drills through a side of the water jacket. Any ways thats how i solved the problem. If you just ignore those bolts and plug the holes i would be afraid of streingth issues. I would not want to do that cus you might start to blow water jacket seals. Another note on this. I did that mod and put the engine together, the bolts went through but were a little tight, but they fit. i had to use a couple taps with the no bounce rubber hammer adn then twist to get the 2 bolts to start but then it was all good. If you guys are going to use a later intermediate plate, there is another problem associated with that. If you put the engine together with the pre 73 housings and a later int. plate you get small spaces under where you header is. On that small flange thats in the AL right above where the oil pan bolts are. Going from that flange to the plate thee will be small oval spaces. about 1/16th inch wide and a 1/8inch long. This is just enough so that you get a massive amount of oil out of your oil pan area and will spray right onto your header etc. I cleaned the area really good and just dabbed some JB weld over it. Next time the engine comes appart i will have to chip that out of the way, but thats not biggy. I sealed it with that and then put some RTV over it for insurance. Hope this helps you guys.

CJG

 

Thanks rotortuner.

I found out my end plate is a genuine '74/'75. '76 didn't have the hole in the upper corner.

 

OK, But your still going to have to drill in order to change those to holes, the one under the exhaust port and the one under the leading plug. Right?

CJG

 

I was going to do what Racing Beat did when using older end plates with peripheral rotor housings. I'll simply tap some threads in the end plate's offending tension bolt hole and plug it with a bolt. The loss of just one tension bolt doesn't seem to cause any probs with a high output PP engine. Infact, '76 engines had an undrilled casting there. The nitrided FB plates don't even have a casting there (and are missing two tension bolts compared to '73 and '74-75). Those FB engines can be turbocharged without a failure caused by missing tension bolts.

Granted, the two tension bolts I'm going to be removing are in the lower half of the engine, where the most stress is, but the engine will never be stressed from a turbo, or experience the high RPMs of peripheral porting. That's why I am only interested in bridgeporting or streetporting. Infact, the way things are going, I may only streetport since there is so little room in the engine bay of a Midget. I guess I could do what RX-Midget did and mod the foot box so I could run some sort of Weber carb, which would lend itself to a bridgey really well, but the car needs to let me know what it wants, so to speak.

So anyway, I'll be using all '73 housings except for the end plate. Drilling the holes out isn't much of an option, or is it? I'll think about it.

 

In the process of spring cleaning my garage, I tried two 12A oil pans ('73, '83-85) and neither one fit the MG. Long story short, it looks like I'll have to go back to a 13B in the Midget. I was planning on puting the 13B in my baja because of its great low end torque, but everything about this engine fits so well in the Midget that I won't have any fitment issues like I'd have with a 12A. The oil pan drain plug clears the cutout in the frame rail, the intake manifold doesn't touch the unibody or upper foot box area, the exhaust header also fits fine, the oil pressure guage fitting is the correct thread pitch and length, the heater core fitting can be easily blocked (there's no heater core), the temp guage sender works, etc. Even the choke on the carb works and it has a great idle when cold.

I'll try to keep this thread updated with my project.

 

Here's an update. I've located a 13B that comes very close to the 13B that was in the MG last year. The oil pan will have to be swapped, the oil pressure fitting will have to be redone, and it'll need a flywheel and pilot bearing/seal, but everything else will fit; even the intake manifold. The only thing I'm not sure about is the heater core outlet pipe. I think I can simply block it like I did on my other 13B, but we'll see.

 

bad news...... the best exhaust for a bridge is open exhaust!


why dont you use a newer motor??SE?? they are alot better in many ways!

 

I thank you for your concern, but I was diluting myself into thinking I could get away with it in my MG without redoing the exhaust. And now the oil pan issue...

Ok, here is what I'm doing with this car: I'm for sure installing a stock ported '76 13B with a RB light steel flywheel as this engine is coming out of my automatic Cosmo (cosmo's getting a newer jspec engine). The light flywheel will prevent at least some of the burnouts I was experiencing with my REPU's engine and its stock heavy flywheel (which was installed last year, as mentioned above). No wonder the 1000hp Supra guys went with lighter flywheels in order to prevent burnouts and decrease their times. There's no point doing a bridgeport in this car untill I can do it all the way. That 13B ought to have enough power for me at first anyway.