Hi everybody,
In about four months I want to start improving my Mini. I have a 71' Mk III with, as far as I can tell, an 84' A engine. The main things I want to do is rebuild the engine, upgrade to a double carb system, upgrade to a better gearbox (5 spd), and disc brake upgrade.

What I'm looking for is just any knowledge anyone would be willing to share about everything above, mainly where I can get the right gearbox. Cheers.

-Zac

 

A five speed won't come cheap. Minispares shows them for about $2700, but they're out of stock. If you want a higher speed cruiser you could change the final drive to a lower number. I have a close ratio staight cut box in mine which makes it pull well in every gear but doesn't help highway revs. To see if your engine is an A or A+ check the block- stiffening ribs=A+ no ribs=A. Good luck!

 

To see if your engine is an A or A+ check the block- stiffening ribs=A+ no ribs=A.

Oh much easier tell tales than that:

1. Does your dip stick slide into a tube or fit flush to the block? Flush is an A+

2. How is your dizzy held down? A single bolt holding down a forked plate is an A+. A bolt holding a collar around the shaft is A.

*****
before you upgrade to twin carbs you might want to compare the numbers of twins vs one big one (HIF44/HIS6 1 3/4) with a sport manifold and then never worry about balancing the twins as added benefit.

****
Given that the Mini never was built with a 5 speed, the only ones you are going to find are aftermarket and I'd expect to pay $$$ for one of those.

 

Awesome, thanks for your help guys. I've been searching for gearboxes and I've seen the ones from minispares, guess-works, and one other I don't recall at the moment. I expected to be paying around $3000 for a 5 speed so, naturally, I've been saving. Judging by your tips, I'm pretty certain I have an A+.

Capt: A question about your 2 vs. 1 carb theory. If I have the engine bored to 1380 or even 1400, would the single, larger carb still be able to keep up the same performance as with two 44's? I know tuning multiple carbs sucks, but if it's worth it, I'll manage.

 

Two HIF44 is way more then you'll need even at 1400 unless you have a really wild cam in their and only plan to use it on the track where you'll be at high rpms constantly. A Single HIF44, twin 1 1/4SU(bellow 1200cc),twin 1 1/4SU(above 1200cc) , twin HS6 SU or a Weber are a better bet. You shouldn't need two HIF44 until you get to 1430+

Also remember with dual carbs your fuel is distributed more evenly, other wise you get the outer two cylinders running leaner then the two inner, especially at lower revs.

You also might want to reconsider going straight to the maximum rebore, as it will leave no room for error and you'll need to sleave it. Plus after two rebores the block will be pretty much shot.

BTW what size are you starting with?

 

Right on. I'm not really planning on taking it to the track. I was probably going to go to 1400. How big is the max bore? My biggest concern for running two as opposed to one was exactly that reason, even fuel distribution.

 

KAD do a good 5 speed box..... http://www.kad-uk.com/mini-parts?product_id=64

 

^Good tip, thanks^

 

I think 1426cc is your absolute limit. At that point your looking at some serious block work including strengthening the bottom block, studs, center main straps and a billet forged crank to cope with the extra HP. Basically at that point it's a bomb waiting to go off, your just strapping it together to try to keep it from blowing apart.

Even at 1380 the blocks integrity is shakey leaving suceptable to breaking through the water jackets making it into a giant paper weight.

Hears a few books to look for to give you some insight:

Haynes Mini Performance Manual (Haynes H880)

Tuning the A-Series Engine- A definative manual on tuning for pereformance and economy - by David Vizard (Haynes H620)
Often refered to as the "Yellow Bible" and for good reason. This book will answer anything you could think of when it comes to perfomance. The guy is a God when it comes to engines.

 

I wasn't planning on going above 1400, but it really all depends on how good of shape the block is. I'll know once I get it all torn down. Thanks for the referrals!

 

to be honest. if you have a standard 1275 block that is in good shape and you plan to bore it out. i would bore it to 1293 or 1310 at the most. this way if you should need to, you still have a rebore later. Also the power "gains" from boring it out to the max on a street car is very little if any..... Some people also had cooling issues due boring it too much and the thinkness of the piston wall being thin. I did this with my mini which pushes 100hp on the dyno with a 1310cc A+ and a single 1.75 HIF carb.

I'm in Hamilton but i get to Windsor from time to time.