850 pistons

[bwaminispeed]

Are there any decent pistons available for 850s.....

Trying to do a near stock 850 motor.....Would like to stay as close to 848 as possible....

[Spider]

County manufacture them.

They are OK, but not a performance piston.

[whistler]

Try Somerfords.

[bwaminispeed]

OK, thanks.....Not building a performance motor as such, just a good small high mpg motor.......

Ideally, some 3 ring high compression, flat top, or, almost flat top...Would prefer 998 style pins, not big on pinch bolts....

What do you think of my cross drilled 850 crank in my previous post....I was kinda shocked when I saw it, didn't know they even existed...

Sommerfords only show rings, which, I may need anyway, if I'm stuck using the original pistons......

[Spider]

The County Pistons are actually a 5 ring design , but most suppliers supply them with 4 rings. If you go to a good quality ring, you could easily go to 3. Something that's plain iron, square faced with a 3 or 4 piece Oil Ring, I'd suggest looking at offerings from Grant or Hastings here.

...Would prefer 998 style pins, not big on pinch bolts....

What do you think of my cross drilled 850 crank in my previous post....I was kinda shocked when I saw it, didn't know they even existed...

Yes, the pinched little ends are something to steer clear of in any engine.

I have read your other thread and did some reading to see if I could ID it for you.

Special Tuning offered a Tuftrided Crank, C-AEG 515, while I've not seen one of these, I'm fairly sure they were a stock through drilled crank, though, don't take that as gospel, that was tuftrided and balanced. Some of the engine tuners back in the day did obtain raw forgings for final machining of their own, I wonder if that's where it came from ?

[Dearg1275]

If you are not building for out and out power from your 850 you will not have problems with your pinched small ends. Millions of 850s carried families and the luggage up and down the roads of the UK and BMC/BL never felt the need to change this arrangement. If they were having serial trouble it would have been changed. The 997 Cooper had pinched small ends and 55bhp as standard and in ordinary use was reliable.

The 998 engines received the floating gudgeon pin as they shared the same bore as the 1098 engines so it was easier to standardise production. The 1098s had the longest stroke which put more strain on the little end which is likely why they moved away from the pinch system.

To my mind the 850 was a tough little engine so you should be fine. If you want some great 850 pistons try and find some Schmidt ones. Powermax did a good piston too. Neither easy to find these days.

Good luck hunting.

D

[bwaminispeed]

From everything I saw when taking this engine apart, it was pretty obvious that it was "as built" from the factory, was very low mileage, and, had never been apart before.....

It has all the latest (for the time) spec bits and pieces, 22G68 B style magic wand shifter, Deva bush large tail crank, Diaphragm clutch, nearly flat top (very small shallow dish) high compression pistons, and, that somewhat bizaar cross drilled crank.....

Very mysterious indeed......