Early Miata information please

Frenchyd,

On Datsun1200.com we have 2-3 members that have converted their Morris Minors to Datsun A-series engines. Note that Nissan built this engine until 2007 so parts supply is very good. The Datsun1200 website will give you dimensions but it's nearly identical to the a BMC 1275

A-Series motor came in 1971-1982 1200, B210 or 210. The Nissan 5 speed used with for the Rivergate 5 speed conversion (from a 210) pairs to the Datsun / Nissan engine.

Displacements are A12 1171cc, A12A 1238cc, A13 1288cc, A14 1388cc & A15 1488cc

The A12 weighs 190lbs complete and the A15 is 205lbs.

The A12 4 speed is 38lbs & the A15 5 speed weighs 54lbs

Stock power outputs range from 68hp for A12 to 92 for the fuel injected A15. With a very mild cam, H89 cylinder head and Weber 32/36 carb your looking at around 85-95 hp dependent on displacement. DCOE carbs will add another 10hp. 

My A12 in very streetable trim made 73whp & my current A15 race motor would be street able and makes 105whp. Both motors revved to 7800 rpm. (It's a 5 main bearing crank that's good for 9000 rpm in stock trim)

We also have a Miata and like most folks here I love them but for  Morris the engine tranny combo is going to add over 100lbs to the car. I'd go with the Datsun engine as it also looks similar to the BMC engine as well as the aforementioned weight savings.

To bad your not closer to Vegas, as I'd give you an A12 motor if your customer wanted it as I have 3 extra street motors. I  even have a mid-close 4 speed tranny that I'd let go for cheap. If you do go with a Datsun motor and are looking for a 5 speed I'm upgrading the tranny in my car so the I likely have a 210 5 speed available in a couple of months.

Of course you can't go wrong with a Miata engine, they're sturdy as all get out.

In reply to Tom1200 :

good info on that Datsun engine.   I’d forgotten that. I actually got Datsun factory training just before I got out of the Navy.  The Vietnam War was just about over and hundreds of thousands of ex servicemen were getting out without jobs to go to.

So the Navy offered us free ( they paid us) to companies who would prepare us for a civilian Job.  

Balboa Datsun who’s owner raced in SCCA  and after the training I worked on the race cars for the last month I was in. 

It helped that my Jaguar was in D production same as his Datsun 2000  so we’d raced against each other.  Big tracks like Riverside or Holtville my Jag could leg it past him but he’d whistle past me on the shorter twistier ones.

I’m worried though about availability of those engines and parts.  This guy has no mechanical sense. Having blown up 4 engines in three years.  At least the Miata is readily available in junkyards and backyards

I’ll  suggest it though,  sure be easier fit and job. 

Every engine part for A-series is readily available except for the crankshaft, cam and rods. Those three are available,they just take a bit longer to get. You can get the cheap-o "racin" rods on eBay (guys have had good results with them actually). Cranks & cams are out there it just might  take 30-45 minutes online hunting for one is all.

To kill an A-series motor you either need to run it completely out of oil or  repeatly overheat the motor, ignore the problem, keep drivng the car for the next 50 miles boiling  fluid out of the cooling system at least three times. Even then it will usually just pop the head gasket.

In reply to Tom1200 :

 I know that the Datsun engine is much stronger and better than it’s British forerunner having built a few for racing. 

I’m going to quote him the same price for the Datsun  engine as the Miata engine.  The work should be similar. The  suspension upgrades will make the Miata a much more costly choice and I’ll explain that the stock rear end simply will not live with a Miata  engine. 

Keith Tanner said:

DeadSkunk said:

Another thought, if you can get the Miata front swap in a Minor, the rear axle from a 4-bolt Fox body Mustang is actually narrower than the Miata front. You could redrill the Mustang axles to 4x100 (maybe) and use Miata spec wheels all around. I've been considering this one myself because I'd like to put the Miata front end on my Corolla, but stick to a live axle rear for simplicity.

Wish I'd come across this while doing the MG! That's good to know. FYI, I had Moser make up some custom axle shafts with the Miata 4x100 pattern on the end. They went into a Blazer rear end that was the same width as the Miata rear, now I wish it had been narrower.

This is interesting to me too. I'm seeing that fox axles (both 7.5 and 8.8) were 57 inches wide. MGB axle is 51.75. I'm not sure that you could easily fit a fox axle under an MGB without shortening. Am I missing something?

In reply to Robbie :

You have to allow for wheel offset in all of this. Ex: My Corolla axle is 54.5" with low offset wheels, while a Mustang is 57". I said earlier that the Mustang axle could be redrilled to 4x100 and use the higher offset wheels from a Miata. A stock Miata track width is 56.2" (slightly more for an NB) and that 57" Mustang could be around 54" track width by using the 38mm offset Miata wheels. I'm not sure how wide Keith's Blazer axle is from mounting face to mounting face. I suggested a 7.5 Mustang as a relatively light weight alternative for the Morris Minor (or Keith's MGB), but only if he were going to use a stock width Miata front suspension to sort of match track widths. Without flares the Mustang and the Miata solutions are both too wide for the Minor, the MGB, or my Corolla..

If I do use the Mustang axle, the car will be flared a little, and will use higher offset wheels. Ford Focus or Contour wheels should work without having to redrill the axles to 4x100. My car is for the Challenge , so mismatched wheels on the front and rear wouldn't be a big deal.

My MG has flared fenders and the stock wheels are pretty tucked. I chose the Blazer to match the Miata front track I was using.

My notes say the 4WD S10 Blazer rear I used is 59". The 2WD version is 55". Were I to do it again, I'd probably go with the 2WD and give myself room for wider wheels in the back.

I also discovered that it was 9 years ago yesterday that I took this picture. Wow.

The S10 axle is a 7.5", just like the Mustang, so it's probably about the same weight. The S10 is about the narrowest axle I've come across, so far. If I were building anything other than a Challenge car it would be the better choice, especially if you were willing to buy custom axles. The S10 2wd axle , with some Moser axles  drilled to whatever pattern needed, is probably the easiest path for anything not being drag raced hard. I'm going to swap meet Saturday. I'll have to watch and see if I can find a Chevy axle to inspect. If it could be easily drilled to 4x100  ( from 5x4.75) it might suit my purposes a little better than a Mustang 7.5 4 bolt. The Mustang ones are pretty cheap though.

In reply to DeadSkunk :

That was simple, he traded it for a 1948 restomoded Buick Woodie plus a check for $200,000 

frenchyd said:

In reply to DeadSkunk :

That was simple, he traded it for a 1948 restomoded Buick Woodie plus a check for $200,000 

He paid $200K for a restomod? !!!

A Morris Minor with a warmed up 1275 is one of my favorite cars. I love them.

I also feel like the Minor is a car where if you change any one part drastically, you HAVE to then change everything about it. Any power over 60hp will require more brakes which will certainly require major front suspension modifications as I doubt the single arm Armstrong shock and trunnion setup can deal with much more in the way of forces acting on it.

Then of course comes a stouter transmission and rear end and different master cylinders and chassis reinforcements and.... on and on. 

Next thing you know you are elbows deep into something like this

Which while awesome isn't what you had in mind when you envisioned a little more power and you lose some of the undeniable charm of the Minor.

But a twin carb 1275 with a peppy cam, a close ratio 4spd and a rude exhaust makes for one of the most fun city cars ever!

Jumper K Balls said:

But a twin carb 1275 with a peppy cam, a close ratio 4spd and a rude exhaust makes for one of the most fun city cars ever!

 

Since you basically described my Mini, I'm gonna agree.

In reply to Jumper K Balls :

If it we’re mine that’s pretty much what I’d do except for the transmission.  I think I’d go with the Ford 5 speed overdrive.  Out on the back roads the engine is buzzing along with a 4 speed and the OD slows the engine enough so you don’t feel frantic.  

I might also skip the cam and go to a supercharger using the aluminum head  with roller rockers and hope I added enough ZDDP to the oil so the lifters last. 

In reply to DeadSkunk :

yeh! I hear it’s spectacular. 572 big block 6 speed manual, really trick suspension and absolutely flawless woodwork.   Parts alone sound like they cost at least 1/2 of that.