dig dig dig

is fitting 1.5 roller rockers a good idea with an 850?

Put a RC40 exhaust system on it - anything other than the pea shooter thing that is original.

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

Nope. Bad idea on a 998 or 1098 too. Usually...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Ok so i only read a few posts at the beginning, but i thought i would mention an 850 my boss has told me a bit about. It was a car he used to race in NZ as i believe heaps of people raced 850's at the time due to the mini seven class or whatever it was.

There is actually an article he kept about him, which says his 850 constantly put 1275's to shame on the track. He also tells me he reckons he could make an 850 go better then a 1275.

So a little bit about what he told me of the engine, it had a compression ratio of around 15 or 16:1, rev'd well in excess of 10,000rpm, and ran on a blend of methanol, avgas and some other special things. I think he mentioned benzol or something like that. He did tell me a hp figure which i think was 130 or 150 at the crank, but that could just be a tall story, so lets just say thats an unreliable estimate.

So 850's can go really really hard, but the catch was it usually melted a piston or some such after 10 laps....

This little car would have to be the quickest 850 in Australia. Its upset a lot of Cooper S's over the years.

The knowlage i gained when this engine was built (by JK at NMP) i have made a similar engine that ill put in one of my cars one day.
Early 850 block, machined to suit 998 crank & cam bearings fitted
New A+ 998 crank, lightened rods & AE pistons 10.5.1 comp
12G206 997 Cooper head
Wade 104 cam & adj double row gears
1.5 Roller rockers
Mk 1 S gearset & 3.4 diff in early case
Lightened flywheel & backplate

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What capacity does that take it to though Dave ?

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998! its a standard stroke 998 crank & std size 998 pistons. The block was overbored 60 or 80 tho from memory, it was about 8 years ago.

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Have a Nice Day.
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d'oh - can't call it an 850 anymore!

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did I tell you that I won a trophy?

It still says 850 on the back of the block!

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Have a Nice Day.
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.. and I still have sane tattooed into the back of my head, but it doesn't make it true

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Simon

The adventures of an owner builder in the Tallarook Ranges

Hey 850 man ,was that a pommy 8AM block. I heard of a bloke that reckons he bored a pommy 8AM out to 70mm.
I am looking at doing a little project eng using a 850 nitrated crank and was wondering about the block

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

The block is a very early 61, its got the 850 cast in a different position on the back, the oil pick up hole is threaded and the 3 holes are in the end above the end main cap where the top part of the rear main "seal" plate would be if it was to be a rear wheel drive type. Very rare these days, i shouldnt have done what i did to it as it was untouched untill i got to it. Anyone got another early block they dont want?

I had a discussion with David Vizard a few yers ago (when he come to Aus) about 850 engines and he said that you shouldnt bore an 850 block past 130thou as the wall thickness gets too thin, he suggested if you wanted to go more you could wet sleeve an 850 block but thats all too hard, you would be better off to use a thick flange 998/1100 block.

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Have a Nice Day.
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Thanks for that info 850 man. I just went to the shed and checked. I have 2 complete eng/boxes the same as the one in the pic . One has a 7/59 dist and the other has a 12/59 dist. the body shapes are slightly different.
The block I was thinking of using is very rusty in the bores and the top. I have cleaned the top off and can find no traces of a number. I removed the welsh plugs and measured the dist to the od of cylinders and it is considerably thicker than the other 850 blocks 8y blocks I have.
I wondered if this thicker block was a 8AM stamped block

PS I looked at the pic again and noted that the flywheel housing is same as these eng. The casting is different to the other 850 ones I have

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Research is the difference between speculation and investment. Anyone who copys some one else will always be second
www.minisprintgt.com

850man,,, i have to say that i understand & appreciate & respect what "You" are building & the specs you have listed for same,,,

But Henrys mini is "NO" 850

It` "WAY" beyond that,,, sounds like you may have been led a "little" astray with it`s specs

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

I've got a pommie block with the 850 same as above but the number is 8A I (or1) - is it a boat anchor or worth hanging on to?

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!