I'm currently preparing an 850 for my Traveller (from a '62) and have just finished stripping it down. Most of it seems to be in excellent original condition. All of the fasteners match and don't have mangled heads, many of the tab washers had only been used once etc. Its clearly done a bit of work because the crank is 20 thou under on the mains and 10 thou under on the big ends, but the journals are perfect and the bearings are good enough to go again.

The slightly odd thing is that all four cylinders are sleeved. Its on original bore sizes, with what looks like original MOWOG split skirt pistons. I know the factory often sleeved blocks, but was under the impression that they rarely sleeved all four.

Does anyone know if there is a way to tell if they are factory fitted sleeves, and is it likely that they would sleeve all four?

What do I do about re-boring it? Can sleeves be bored 10 or 20 thou, assuming that I can source some oversize 850 pistons. Alternatively should I have it measured to see if the sleeves can be pressed out and 998 pistons fitted?

Tim

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1951 Morris Commercial J Type Van
1955 BSA C11G
1961 Morris Mini Traveller
1969 Triumph TR6R
1977 Leyland Moke Californian

If its factory sleeved ,it will have an 'S' on the end of the engine number on the block .....

You should be able to bore factory sleeves to +.020".
If the factory sleeved a block, they usually did all 4.

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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.

Thanks Doc, that's good to know. I'll get it mic'ed and see how bad it is, then attempt to get some oversize 850 pistons.

If that doesn't work I'll have to look at the other options. From some rough measurement of the sleeve wall thickness, I calculate that if it was bored to use 998 +.080" pistons, it would clean up the sleeves, but I don't know what they're hiding.

Tim

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1951 Morris Commercial J Type Van
1955 BSA C11G
1961 Morris Mini Traveller
1969 Triumph TR6R
1977 Leyland Moke Californian

You can probably get O/S 850 pistons here, no I've not used any of theirs for 40 years..
http://www.jp.com.au/JPPistons.html

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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.

At work we got some JP pistons for an 850 we did up a year or 3 ago so i would assume they are still doing them