850 Pistons

[Thorp]

Hi All,

I've acquired an 850 race block (pocketed for big valve head) with main strap, cam bearings etc as part of a job lot of parts.

Can one get decent pistons for 850's any more, or is the solution to use the 948 Sprite piston and deck the block?

Any advice gratefully received.

Thanks

[Spider]

Try JP's

http://www.jp.com.au/JPPistons.html

[Thorp]

Ok thanks. Will take a look.

Any in Europe anyone is aware of? I would like it to be able to rev a bit.

Thanks

[CooperTune]

I have been building some UK Moke 850s recently and finding pistons for the job has been a problem. I lucked into a couple of sets of Repco pistons in .020. They were new in the box with paper work dating back to the 70s. No two pistons were the same size so miked and honed each cyl. and marked pistons for hole. I think Calver's buddy in OZ had some sets made, not sure they are good for high RPM. There is little to no demand for Hi Po 850 parts. I was talking with an old timer (takes one to know one) his take was the ultimate 850 is a 970 Cooper S. If someone could help me find a set of S journal size 6 inch rods I'd assemble my 970 and find out. Steve (CTR)

[Smiffy]

http://twinkam.co.uk/epages/191f6b26-60 ... ucts/SC239

[nick rogers]

I have several sets of 850 pistons from std to (I think) .060". From memory they are 15037. I will put them on the for sale section when I have checked them out, but if anyone is interested I can offer them straight away.

[Spider]

I've just been on the phone to one of my trade suppliers about other bits and I inquired about 850 pistons. He does still have a few Hepolite sets there, in various sizes - +0.020", +0.030", +0.040" and +0.060".

[Thorp]

Thanks guys.

Are the 15307 the standard split skirt piston, or an uprated one? I would ideally like to be able to rev it safely to approx 7k rpm, which would exclude the split skirt ones I guess. I believe the later 850's had a solid skirt piston which presumably can stand a little bit more?

[mk1]

I would ideally like to be able to rev it safely to approx 7k rpm.

You won't be able to rev a standard 850 crank to 7,000 safely regardless of what pistons you are using.

[rich@minispares.com]

I was talking with an old timer (takes one to know one) his take was the ultimate 850 is a 970 Cooper S. If someone could help me find a set of S journal size 6 inch rods I'd assemble my 970 and find out. Steve (CTR)

the 970/850s used a Gordon Allen crank in the 970 unit to destroke it further

we used to have one of the cranks as a door stop here at work - its just been donated to someone who is building a short stroke screamer 16v bmw headed thing.

I bet its going to howl!

[Thorp]

Thanks Mark. Agreed.

Am on the look out for an old special tuning crank (aeg515 I believe?)