as above

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68 Mini
70 Moke

Depends how many re-bores it's had before. Are we talking 850, 998, 1100, 1275?
The standard overbore sizes are +020, 040, and 060 thou, but you can go much larger in many circumstances.
KB

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1275 bored to 1293 one bore scored

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68 Mini
70 Moke

still got two over sizes left 1310 1330
i once had a slight score in the bore were a gudgion pit come loose ...
so slight that the sump filled with water
makka

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Anonymous moderation means the agro that is built up towards the mods isn't aimed at an individual (fewer "Makk" attacks). Less stress for mods means less moderator "retirements".

How much slop is there between the piston and the bore (is it atight fit or is the block due for reboring as well ? How deep is the score ? You need to work out how much the block will need to be bored to overcome it . For the capacity you mentioned I think it's 20 though over so that's good , but if the motor's worn it might need to go to 40 thou or even 60 thou if it's been well used and if the score is particularly deep then it will need to go further . Is this a motor you have now or are looking at and have been told one bore is scored ?

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1293 is only +020. So depending how deep the score is that leaves you with +040 (1310), +060 (1330), then 1360, 1380. Take it to a machine shop for them to measure up and advise how much might be needed to bring it back up. Sounds like it may well be able to be saved though.
KB

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ive heard you can up to 120 thou oversize in a mini block??

Thats a fair bit would that require offset boring

Brenton

Okay This is a motor that I am going to go and have a look at. Spoke to the guy today so I dont know much yet, just thought it would be wise to know what to look for/measure so that I dont buy a dud and waste my money........

so yeah any help would be appreciated....

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68 Mini
70 Moke

The point we're making is that it would be doubtful you could easily measure it, but, the largest oversize (I think) is +114. That's what the 1380 size equates to in imperial (1360=73.5, 1380=74mm not thou, whereas the smaller overbores are given as thousands of an inch). Given it is a cylinder we are talking about then the overbore has to be applied across the diameter. You've already had 20 thou taken off already (in the first rebore), so I make that 0.114 - 0.020 = 0.094 left, which is then across the diameter, so the scoring can be no more than half of 0.094 or 0.047". Can you accurately measure 47 thou in the scoring?

That's the logic I would apply, would welcome scrutiny to check I am correct though.
KB

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You could sleeve one bore if that's all it takes. Then no need to bore far to reclaim the block.

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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.

how much would it cost to sleeve one bore? and then how far can you bore a sleeve?

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68 Mini
70 Moke

a sleeve fitted will cost you around $100, then you can bore it and the 3 others to 1360 (73mm) at least.
Rebore of 4 cylinders another $100-150 total.

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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, so would be a fairly safe bet unless the score is through the bore?

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68 Mini
70 Moke

Even if through to water jacket it still will work.
Unlikely to be anywhere near that.

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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.