Uprating Mk1 850

[stigproducts]

I have got an 850 Mk 1 and would like to fit a bigger engine- it is
quicker to walk right now!
I am thinking a 1275, and obviously some suspension and brake mods to
go with it. before I start I am thinking will a new engine and subframe
from a later car just fit straight in or are the early/late shells
different? I apporeciate even if it does things like cables will need to be
reouted differently. I keep meaning to go to a big mini show and ask around-
maybe you guys can get me started?

[phil hill]

Pretty much anything from a later car will fit an early one. A major difference from your point of view is the front subframe mountings changed in about '75-'76. The two bolts mountings each side on the early cars was replaced with large single bolts each side.

I think the steering racks were different on early cars, Peter would know from his classic rally car knowledge.

If it's really early ('59-'60, push-button floor-mounted starter, silver-faced speedo with clear plastic - red-tipped needle, cord door pulls etc) and it's in good condition then it might be worth more restored than messed about with.

[stigproducts]

Thanks, yes it is a very early car with all the things you mention, 36,000 miles in the family from new!

I wonder in light of what Phil has said then if the engine-subframe mountings are the same? Could I keep my subframe and drop in a later engine?

Any other advice gratefully received.

[Cooperman]

I would go for a 1275 GT block, not an 'A'-plus, a 1.75" SU carb on a late Mini-Cooper manifold, and lcb exhaust with a nice exhaust system and a 'pot-joint' type gearbox. Stick with the original sub-frame or you'll get in an awful muddle. Use, say, a Cooper 'S' (early) dizzy, or an Aldon one. You'll find most things will then be OK, like choke cable, battery leads, solenoid & solenoid connections (use the original inertia starter, not the pre-engaged one which has a different starter ring) and a pre-Verto flywheel.
For brakes use the 7.5" Cooper 'S' set-up if you can afford it. A later 8.4" disc assembly can be used, but then you need 12" wheels, and they are just not right for a Mk 1.
The braking mods are, probably, more important than the engine change. I once had a Mk 1 with a hot MG 1100 lump, but with standard single leading-shoe front drum brakes!! Absolutely frightening. I once had to spin it on the handbrake to stop in a hurry on a main road (but that was 1969).
It would be wise to get new dampers as well plus 4.5" wide wheels. You will need different wheels with the bigger brakes as the offset on the 850 ones is wrong.
There is quite a lot to such a modification, apart from the elimination of the originality of a Mk 1 850, which should increase in value over the years. To maintain/increase its value with a bigger engine you would need to create a replica 1275 Cooper 'S' Mk 1.
Contact me if you need any more assistance with this.

Peter

[Cooperman]

Just thought, if you do fit 7.5" 'S' brakes, don't forget to fit the 'S' master cylinder. I think it's the same bore, but it holds more fluid to cope with the calipers' greater capacity. You might feel you need a servo as well, although some people prefer to drive without.
Maintenance tip of the day - when fitting either brake or clutch cylinders to early cars, don't use a split pin to retain the clevis pin, use an 'R' pin. It's easier to fit and easier to remove. Of all the jobs on a Mini this must be about the worst, unless you know differently.
Now, what is the worst job on a Mini? Answers please!

Peter

[Fatboy]

Cooperman said:

Now, what is the worst job on a Mini? Answers please! Peter

Possibly worthy of a new thread methinks.....

My vote is fitting that gearbox oil seal anti-leak thingy - absolute weapons-grade bastard to fit, and I had bits left (cheers to Plotloss for reminding me of that the other day ) I wish it had come with instructions

[xxplod]

If I had an original Mark 1, I'd keep it that way. There are so few about it would be a shame to make any irreversable changes to it.

[Cooperman]

For the cost and amount of work involved in converting a Mk 1 850 into a 1275 of some sort is probably more than the cost of buying, say, a 1990/1991 Cooper 1275 (Carb model). Then you have to consider the devaluation of the 850 as these are going up in value. If building a replica 1960's Cooper 'S' 1275 from your 850, you would need a proper 'S' block, which would cost a fortune. The twin SU's would cost a bit, plus the correct manifolds for the twins, then there is all the trim and other special 'S' bits. You could be looking at several thousands of quids to do this properly.
Think long and hard before you start out on this.