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i've got an 869 if you're keen..

postage may be a bit.... unless someone is headed up that way?

Anyhow-
If boring the 850 block and using the 850 crank, the easiest piston choice now is use 998 ones, and deck the block by 4.0mm to suit.

you don't have particularly flamboyant dreams do you?

and by 869 i mean an 850 engine 30 thou overbored..

Cush is that an assambled short motor or what?

With whats been said in mind. If ya fit 998 pistons & rods (std or 60tho), deck the block and balance everything what's the options on the head and cam. Would a std 998 or 1100 cam do nicely or maybe a wade 112 or 104 and just use the 'wadecam' specs for the rockers etc? When you said no high reves how high did you mean? I do'nt even take the 1275 over 4500rpm.
What would be a good head, is their any difference between the 848 and 998/1098 heads? It would be ported and polished.
Lastly any ball park figure on power atw? or is the specs still to vague to be asking that.

Author:	Kennomini [ Sat Oct 27, 2007 6:10 pm ]
Post subject:	Hot 848???
Just curious what can sensibly be done to a 848cc engine and magic wand box? I'm talking about a reliable daily drive that looks fairly standard and period in the engine bay but with impressive internals. Some ideas I've had are worked to suit 1275 head, decent cam, bored out and possibly stroked pistons etc etc. Also what can be done to the std box, is it possible to go full syncro and fit a CV joint diff? Any words of wisdom, advice and ideas would be appreciated.

Author:	drmini in aust [ Sat Oct 27, 2007 6:57 pm ]
Post subject:
30 years ago I used to bung new 1098 cranks rods and pistons into 850s... I would preferably start with a 998 block, rods and crank. Because- 1. All Oz 850s only had a front cam bearing, the 2 other cam journals ran direct in the cast iron block. This means use no high revs, big cams and heavy valve springs... 2. 850 rods have a split little end and a pinch bolt. Not near as strong as 998 ones. 3. You can fit a 998 crank into an 850 but the centre main web of the block needs to be machined each side, because the 998 and 1098 cranks are 1/8" narrower there. You then use 998 main bearings, but still can only fit the narrow 850 thrust washers. 4. An 850 crank may be short stroke but it's not real strong, as the webs are narrow. I broke one... and I wasn't trying hard. Anyhow- If boring the 850 block and using the 850 crank, the easiest piston choice now is use 998 ones, and deck the block by 4.0mm to suit. My suggestion- If you want a good revver I would just get a 998 and bore it to +.100" or +.120". Russell Engineering and www.minis.com.au have flat top pistons to suit. Balance it and build it properly with the right bits and it will be almost bulletproof.

Author:	cush [ Sat Oct 27, 2007 7:14 pm ]
Post subject:
i've got an 869 if you're keen.. postage may be a bit.... unless someone is headed up that way?

Author:	mr_a_series [ Sat Oct 27, 2007 10:47 pm ]
Post subject:
cush wrote: i've got an 869 if you're keen.. postage may be a bit.... unless someone is headed up that way? tis a dream but how much m8 lol

Author:	cush [ Sun Oct 28, 2007 12:07 am ]
Post subject:
you don't have particularly flamboyant dreams do you? and by 869 i mean an 850 engine 30 thou overbored..

ausmini https://ausmini.com/forums/

Hot 848??? https://ausmini.com/forums/viewtopic.php?f=5&t=37148	Page 1 of 2

Author:	Kennomini [ Sun Oct 28, 2007 4:52 pm ]
Post subject:
drmini in aust wrote: Anyhow- If boring the 850 block and using the 850 crank, the easiest piston choice now is use 998 ones, and deck the block by 4.0mm to suit. What cc would that give? and because I'm keen on forced induction if I didn't deck it or only decked it slightly would that act as a low comp set up?...proably a stupid question cush wrote: you don't have particularly flamboyant dreams do you? and by 869 i mean an 850 engine 30 thou overbored.. Cush is that an assambled short motor or what?

Author:	drmini in aust [ Sun Oct 28, 2007 5:46 pm ]
Post subject:
With std bore 998 pistons it'd be 895cc. With .060" over 998s it'd be 937cc. Note if using 998 pistons you ideally need the 998 rods too, otherwise you need grooves cut in the gudgeon pins for the 850 rod clamp bolts. Leaving the pistons far down the bore gives a very poor chamber shape with no squish area, so poor chamber turbulence. Not a good idea. Open the head chambers up instead, then it'll breathe better too.

Author:	Kennomini [ Sun Oct 28, 2007 7:01 pm ]
Post subject:
With whats been said in mind. If ya fit 998 pistons & rods (std or 60tho), deck the block and balance everything what's the options on the head and cam. Would a std 998 or 1100 cam do nicely or maybe a wade 112 or 104 and just use the 'wadecam' specs for the rockers etc? When you said no high reves how high did you mean? I do'nt even take the 1275 over 4500rpm. What would be a good head, is their any difference between the 848 and 998/1098 heads? It would be ported and polished. Lastly any ball park figure on power atw? or is the specs still to vague to be asking that.

Author:	cush [ Sun Oct 28, 2007 8:07 pm ]
Post subject:
Kennomini wrote: Cush is that an assambled short motor or what? attached to a gearbox....has everything in it.. has a head just resting on it atm.. you could have a choice of heads.. (see my forsale thread to stop this hijack )

Author:	drmini in aust [ Sun Oct 28, 2007 8:19 pm ]
Post subject:
Kennomini wrote: With whats been said in mind. If ya fit 998 pistons & rods (std or 60tho), deck the block and balance everything what's the options on the head and cam. Would a std 998 or 1100 cam do nicely or maybe a wade 112 or 104 and just use the 'wadecam' specs for the rockers etc? When you said no high reves how high did you mean? I do'nt even take the 1275 over 4500rpm. What would be a good head, is their any difference between the 848 and 998/1098 heads? It would be ported and polished. Lastly any ball park figure on power atw? or is the specs still to vague to be asking that. 998 cam is same as 850 so meh... 1098 cam not much better. Wade 104 is OK I run one in our 1293. Use the stock 850 rockers, not high lift ones. When I say high revs I mean 6000 or more. 848 and 998 heads are same inside. I'd get a 12G202 (1098 head) and port it a little- don't make the holes too big. As for power I don't know, I've not tuned an 850 really for 30 years.

Author:	Spaceboy [ Mon Oct 29, 2007 2:27 pm ]
Post subject:
http://www.ausmini.com/forums/viewtopic ... hlight=850 http://www.ausmini.com/forums/viewtopic ... hlight=850

Author:	Kennomini [ Mon Oct 29, 2007 5:14 pm ]
Post subject:
^^^^^Yeah they helped the whole idea behind this is to say it's an 850 even if it has 998 internals

Author:	drmini in aust [ Mon Oct 29, 2007 6:18 pm ]
Post subject:
If you try hard enough, you can get an 850 out to 1220cc... but there won't be much 850 stuff left inside! And for what it costs you might as well go buy a 1275 to start with. There's a member on here with a 1293cc `850', well 850 is what the engine number reckons it is.

Author:	Kennomini [ Mon Oct 29, 2007 8:32 pm ]
Post subject:
well that's one way to get a high powered 848 when I swaped my engine to 1275 I was tempted to stamp the 998 numbers on it but decided to do it properly Their is a power tuned 850 in a miniworld mag from memmory, I will have a look at what it's specs are and maybe ask some more questions

Author:	drmini in aust [ Mon Oct 29, 2007 8:56 pm ]
Post subject:
They used to get pretty silly HP from them in Mini7 Racing in UK, but they didn't last too long. PM `graham in aus' for info, he used to race `em there. One thing to remember though- most of the old 850s we got over here had a thin (1-3/8") crank tail, they were not too strong. The UK racers used the later ones which were 1-1/2".

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