Alright guys I'm currently getting parts together to swap a 13b into an MG Midget and need to verify a bit of old knowledge.

Looking to use an s4 n/a block/ rotating assembly with an s5 TII trans.
Already have the block/ trans.

Here are the parts I believe I need. Please correct me if I'm wrong

-s5 TII starter
-s5 TII slave cylinder
-s5 TII flywheel
-s5 TII clutch
-s4 n/a counterweight

I beleive that will keep the rotating assembly nice and happy but please inform me of wrong info. Much appreciated.

-jj

 

S4 TII and S5 TII have the same flywheel, clutch, starter, and slave cylinder. The only time you need to worry about the series is for the counterweight.

 

so basically...

-TII starter
-TII slave cylinder
-TII clutch
-TII flywheel
-s4 n/a counter weight

is the above correct?

 

-TII starter
-TII slave cylinder
-TII clutch
-S4 TII stock flywheel or aftermarket flywheel + S4 auto rear counterweight
-s4 front counter weight

 

Just noticed: if you use the stock flywheel, the "counterweight" is built into it. The safest option would be the S4 counterweight with an aftermarket Turbo lightened flywheel. The driving experience is worth the extra cost.

 

+1.

 

I can tell you a few things wrong with your idea. Hmm, better yet let me suggest a few ways to improve your chances of success in getting this thing up and running quickly.

Get an NA trans. Why? Because the T2 is bigger, heavier, shifts slower (or likes less RPM when shifting), the starter mounts further out and will cause you to curse and hate life for a while because it will foul the frame rail and/or driver's foot box (and the gas pedal). The car is super light and doesn't need a trans capable of handling lots of torque. You're staying NA, right?

You also only need a 225mm pressure plate that is STOCK duty. Again because the car is tiny. Don't bother with any kind of Racing Beat street strip or any other so called heavy duty pressure plate because in an MG Midget, stock is considered heavy duty.

The NA starter can then be used and it will just fit with a few mm to spare. I say this from personal experience. I can not condone the use of a T2 trans and its starter that mounts further out. Oh and the shifter will have to be moved (relocated) forward. Otherwise it could end up behind you. Reaching back to shift is kinda dumb but I think the Shelby Cobra is like that. I guess you could bend up a long shifter lever, but I think you'd want a short shifter, right? Mine has a super short throw shifter in the right place.

As far as your engine choice, um there is a guy who did an S4 NA in his Midget a bit over ten years ago called RX-Midget (search). It is the yellow race car. He used a weber side draft and had to chop into the passenger's foot box area due to the aux port actuators and all the room they require. Hey, if that's what you want to do to your car, be my guest.

As for my car, I went with an older 1st gen based 13B with Y plates and got to use a 76 Cosmo reverse runner manifold that can be installed and removed while the engine is in the car! And I didn't even have to chop out my foot box! I'm wondering if a T2 engine and its block-hugger intake manifold might be the better choice for you right about now?

As for the flywheel, I went with an RB light steel in 225mm but I could have gone with an aluminum and was about to but decided, after much debate, to stick with the light steel. The disc and pressure plate are stock duty 225mm. The clutch master and slave were swapped out for a set from an S4 NA. The diagonal mounting holes can be used here with a little creative filing or drilling out of holes or whatever. I don't recall all I had to do, but it was kind of involved. This mod was recommended by RX-Midget. I recommend it too as the master will match the slave. Still watch for a super short travel pedal when you're done, and maybe take steps to change the pedal ratio (leverage) length from above the pivot poin to below or vice versa. You'll see what I'm talking about.

Both his and my exhaust systems are long primary. The little dual pipe header was probably the most difficult header I've ever fabricated. I won't tell not to do a long primary, because for NA nothing beats it, but it is a bit more involved than a short collected, but either way the two pipes must exit the engine and turn down 90 degrees and fit through the little hole, then 90 rearward and so on. Once you're under the car, might as well go long primary. It's super easy at that point.

The oil cooler is mounted out in front of the radiator right behind the grill.

The radiator is an old school 1st gen short style with a 10" electric fan on each side. One is a pusher and the other is puller, both wired up but untested.

The fuel system is... actually I haven't gotten that far yet. It's next on the list.

Was any of this helpful?

Check out the link to my https://www.rx7club.com/old-school-o...roject-515846/

 

That was a lot of great (and weirdly specific) info and I'm sure the op will appreciate it.

Not to get too far afield but I'd be remiss if I didn't comment on your fan set up.
Basically, it's the worst of all possible options.
Pick one fan (the puller would be the best option) and delete the other.

 

Well, I've had a rotary MG Midget for a while now and had access to lots of parts combinations, and I've found what works, and I'll be honest, what hasn't. What I recommended is what worked best for me.

I did the same dual fan setup (one pusher, one puller) on a tall style radiator in a rotary baja project recently and tested one by one, then both, and they move more air when they're both on. How is that the worst of all possible options? Is it because the pusher partially blocks the part of the core where the motor covers it? Why is that so wrong? It's not a very large area, at least on a 16" fan. Now the tens in the MG, I can kinda see that, but with the success of the 16s, it spurred me on to do duals in the MG too.

I'm not knocking your info. I'm seriously asking because I'm intrigued by your air of self assured opinion about this. Ever done duals before? Ever found out that they really do suck and that the pusher should just not be done? Any specific stories or experiences to share? I'm sure they'll be useful to this guy since he will have to go the electric fan route. I certainly wouldn't do a clutch fan in one of these. Hey, what if one fan dies and you're stuck in traffic? A little redundancy is a good thing, right?

Other than the obvious blockage in one smallish area, why is it the worst possible of all options? The extra load on the electrical system maybe? I've just spent the last two weeks wiring up the baja for this exact reason. Oh that reminds me, I need to load down the baja's electrical with all lights on, then turn on the fans and see how much they dim down. This should be good...

Oh now I'm turning this guy's thread into a conversation about my stuff. Ok, I'm done with the hijack.

 

My experience in fan behavior stems from watercooled PCs.
Because it doesn't move, the only airflow comes from fans, so it's a clean testbed for fan config/results.

Consistently best was the puller config, followed by pusher.
Push + pull was a distant third.

We were paying attention to proper shrouding and spacing the fan off the core (to eliminate the hub "dead spot") and I was monitoring water temp both at the inlet and outlet of the rad.

Push/pull sometimes equaled the "push" arrangement but NEVER was as good as "pull" alone.
The general theory was that two fans were never perfectly in sync and one fan was always starving the other.

Shrouding and fan placement are more important than the (supposed) extra flow from a second fan.
Companies like Black Magic tout the CFM numbers but fail to give you the supporting documentation.
Like...was the flow measured in free air?
Slap that thing on an obstruction (like a radiator core) and see what happens...both flow and noise (which indicates turbulence) worsen.

Before I resorted to a push/pull setup, I'd rethink the pull only config and try to improve it, because ultimately it should be the best performer.

 

ive been playing with a 1980 MGB this year, and at some point in the 70's they moved the radiator forward and put 2 puller fans on it. weirdly this setup seems to work really well, i wonder if the midget had a similar revision?

 

So I had some medical problems with my wife's health recently and haven't thought much of the car.

Now that she's all good I can revive this wealth of good information.

I have three things to address
1. fan setup will be dual 10" pullers
2. front end is sliced and will be using custom radiator mounting and fiberglass front end.
3. I will DEFINITELY be finding an s4 na trans now that I see the starter/shifter is going to be such a huge headache.

on to another question. I've been using most of rx midget's designs for the build so far and didn't realise the side draft might be a hassle. Although I could just slice out the side of the passenger foot well and fab the trans tunnel to continue down to enclose the passenger footwell that way the motor could still be pulled without having to mess with the carb setup. How far into the foot will the carb have to go? 6"? 12"?

 

Glad your situation has improved.

Glad you'll go with dual 10" pullers. I don't have the room to do two pullers so I had to do one pusher and one puller but they're still untested electically. I'll get to it maybe later today and see how they compare to the other setup with dual 16" fans.

Glad you're doing an S4 NA trans. You can shorten the shift rod to whatever will fit the car best. Also check out the pics of how my car was set up for the trans mount. Or just do like everyone else where they somehow bolt the trans to the stock MG crossmember. I personally like how mine was set up because I could use a competition trans mount for any 74-85 tranny. Your setup will obviously have to be different.

I don't know how much you'll have to cut for the carb because I didn't end up cutting mine.

 

I didn't get around to testing the fans yet but I did do a quickie engine pull to swap to a freshly resurfaced aluminum flywheel from Racing Beat. It also got a thick stock duty 225mm disc and a stock pressure plate, both the Daikin brand. Got it back in and the clutch pedal feels good.

But before the engine went back in, I added an O2 bung to the header because it's really hard to get in and out of the car with the engine in the way, and it's a lot easier to drill a pipe and then weld a bung when it's not in the car.

Click for pics. https://www.rx7club.com/old-school-o.../#post11867322

 

I love this entire concept.
We (I) spend so much time thinking about what engine would improve the FC, but this is the flip side...what car could best utilize the rotary characteristics.
The Midget is a perfect choice.

 

i think the rotary would fit the MGB better, and i have seen a few rotary spitfires as well.

oh and if you want the bombshell, i measured up my Tr3, and a 20B is shorter than the stock 4 cylinder by a couple of inches, imagine how scary that would be!

 

Jeebus, a TR-3 is on the edge with stock power, more would be a real butt clencher.

My favorite thing about Brit cars is that doing thirty feels like doing 100mph...all the thrills with none of the speeding tickets.
Put actual power in it and it'd be terrifying.

 

i told Jeff that doubling the power in his Midget will be like getting Alfred Hitchcock to run the mile in under 7 minutes!

so i completely agree. all the thrills are there already, and they usually sound really good too, so why change that?

 

I think the long primary on mine is gonna sound amazing! Long primaries always have more exhaust note character than any short collected, and sound a lot better than any stock manifold which mixes them right after they leave the engine. Keeping the pulses separated for a really long time shapes the exhaust note in such a way that it might actually make a rotary sound like the classis brittish sports car sound. Let's hope.

 

it should do quite well, in that department.

 

You know back in 1989 when the PO was driving this thing almost daily, it did actually sound like a slightly louder somewhat stockish MG Midget. Or so I thought. My uncle, who knew something about rotaries and had driven a few of them back then, liked the way it sounded. We heard it coming up the hill from around the corner and just stood and stared as it drove by. I think he got goose bumps and said, "Yeah, that's definitely a rotary." Hmm.

I was so profoundly affected by the concept of a powerful rotary going into a micro car like this, that when the opportunity came up to get it in 1996, I jumped on it immediately. Kinda went in over my head, which is why it's taken so long to get any real work done on it, but things are getting done as I'm learning how to do them. I'm also vastly improving things over the original setup it had. Right now I'm adding a heat shield above the header because the foot box acts like an oven to the intake manifold. Next I've got some DEI floor and tunnel shield stuff to add under the passenger floorboards (if needed).

 

Let's do more than hope, let's make it so.

The classic Brit sports car sound, much like wine, ages and gains timbre due to the constant accretion of oil on the exhaust. Each exhaust will develop it's own particular sound depending on the type of leaked oil and exactly where on the exhaust it is dripped.
It's a roarty Stradivarius.

Being of Japanese origin your replacement drivetrain lacks this penchant for free flowing lubricants and the exhaust will probably rust away before developing its voice.

I have a fix.

Premix your rotary's fuel but retain the OMP.
Route the OMP delivery tubes (extend as necessary) to various parts of the exhaust and set them to spray (or drip) in the required pattern to achieve the sound you want.
Your exhaust tuner might have suggestions based on experience, which is vitally useful because like bonsai, this is a process that can take years to mature.

You may not live long enough to experience the car in "full song" but think of this as a "pay it forward" commitment...the seed you plant for future generations to enjoy.

Oh, wait.

This is the "bargain" MG we're talking about.
Because Lucas designed the electrical system to treat the chassis as a sacrificial anode, the car won't last that long either.

 

*oops