850 Tuning

[StuartA]

Hi, I have a 63 850 mini, where the engine is totally standard, with the original HS2 carb, can anyone advise on how i can have the engine tuned to get more power, i understand that stage 1 tuning kits are questionable and the stage 2 kit includes a new head etc, but for me this would i think be overkill, so is there anything i can do to 'pep it up' a little. Thanks

[Thorp]

Best bet is to read some literature on the subject (there is a lot out there on a series tuning) and decide how far you want to go and what your budget is.

Usually, cylinder head (998 cooper head skimmed for example) and carb/filtration and a better exhaust manifold are the starting points.

You need to consider how many miles the engine has done as well; no point "pepping up" a worn out lump.

[pad4]

Shortock supercharger

[mini63]

Hi, I have a 63 850 mini, where the engine is totally standard, with the original HS2 carb, can anyone advise on how i can have the engine tuned to get more power, i understand that stage 1 tuning kits are questionable and the stage 2 kit includes a new head etc, but for me this would i think be overkill, so is there anything i can do to 'pep it up' a little. Thanks

There are a number of things you can do with an 850 which usually ranges from extra carburation, header exhaust and muffler to modifying the engine, head and camshaft.

You can also just try simple things like a tune up, higher octane fuel, remove the air cleaner and fit a ram pipe

[1071 S]

Higher octane fuel won't buy you anything ......unless the timing is presently retarded to allow for the use of cheaper fuel....

Maybe get a copy of one of Clive Trickey's books <https://www.amazon.co.uk/Books-Clive-Tr ... 20Trickey‎> to see what's possible??

Back in the day we used twin HS1s and handmade manifolds. Probably not wise choices ..but with no Internet there was no one to point out our stupidity

Today I would think a single HS4 and a Cooper Freeflow exhaust might be the obvious steps until you can afford a new cylinder head etc etc. Or simpler still... look for a useable 998 at the local wreckers (do they still exist?)

Cheers, Ian

[Spider]

I'd just like to suggest you look carefully at the cash input for the result output before you go too far down this road.

It's easy to spend huge sums only to get similar results to say a mild 1100 engine. I'd also say that the longevity of the 850 when tuned, isn't great, but depends on how it's treated too.

Not trying to talk you out of it, just go in with the eyes wide open!

[ianh1968]

Some of the really simple and cheap mods will give good results.

Try taking the elbow spout off that goes between the air filter and the carb inlet.
You will most likely find that this is full of sharp edges that can easily be removed
with a small file. Streamline the inlet, if you will...

If you can find a piece of ducting hose a yard long, push this over the filter inlet
and put the other end into the grille area so it picks up colder air.

I did these two "mods" on an 850 many years ago and there was a noticable difference.
(and if you can't tell any difference, it won't have cost very much to find this out).

Ian

[CooperTune]

My first mini in 1968 was a 1960 850 Morris. Picked up the complete car for $350. US. I was in high school and working two part time jobs. Got a Trickey CCC book with the car. I had the 850 block line bored for the center and rear cam bearings. Bored cyls .060 O/S with Power Max pistons. Rods were lightened polished, balanced and shot blasted. Flywheel and Cooper S back plate were lightened and balanced. The coil springs in clutch were replaced with HD inner and outer springs. A new two pc. Cooper S front pulley, damper and S duplex timing set. Rotating assembly balanced. Block surfaced for zero piston to deck. A lightly ported 295 cyl head with O/S 1100 valves surfaced .125. Fitted with dimple studs isky springs and retainers. Also used Isky push rods and lightened lifters. Welded pressed steel rockers and a 510 Cooper S camshaft. Cooper S dizzy and a twin 1 1/4 SU intake from 998 Cooper. All on top of a 998 4 synchro remote box with MG 1100 4.10 CWP. Exhaust was by Cooper S pressed steel 3 into 1 and 24 inch Cherry Bomb. I auto crossed / sprinting every weekend I could find one. Drove the car daily during two years of college. It was turned 8000 rpm everyday of it's life. Was a consistent top five behind two Cooper S and two Super 7s on 6 inch revs and Goodyear slicks. I used felt oil filters and Formula R Castrol for the sweet smell. Traded the car and power unit plus $300 US for a 67 Cooper S complete less power unit. I followed the car though two more owners before being drafted into the service and losing touch. Steve (CTR)

[mk1]

The first thing that you should consider changing is the head. Without that you are wasting your time & money.

A decent 850 spec is;

Decent clyinder head.
cut down & ported standard cast iron manifold.
Frogeye sprite back box on standard Mini exhaust pipe.
single HS4 or twin H1 Carb
Ideally 1.5:1 off set rockers

The above will give a reliable increase in power but will remain reliable.

There are loads of threads about tuning 850. Try doing a search.

M

[abri]

I'm reading this thread carefully because I'm interested in doing some modifications to my 850 as well. Regarding the H1 carbs, I have a set on a manifold of unknown origin. My original idea was to fit the H1 carbs on a Cooper inlet and use them on a 202 head. However I noticed the stud holes in the carbs on the manifold side are completely different. Now this manifold of unknown origin has tiny ports (significantly smaller than the Cooper one). This also means the manifold won't match the ports on the head for diameter. Is it worth trying to match them by opening up the manifold as much as I can? Will this mismatch not play havoc with the air flow/speed?

[AWOODY]

Put a 1100 crank in yes it can be done with a bit of machining , you retain your 850 engine number which shocks the hell out of people when they ask what you have under the bonnet , "why an 850 of course" plus a few other mods ,cam , carbs , head ,etc about 48 hp at the wheels and a hell of a lot of fun when they look at you and say " it's only a 850 ! "as you blast away from them , the grin factor is ENORMOUS.