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MG MGB Technical - Groove/scratch in cylinder bore

Hi,

I have an engine that has have very little use after a rebore and rebuild - some time ago. The engine was running very well prior to being removed.

However, after taking it apart to check bearings and general wear I noticed a pretty deep but short groove at the very bottom of one of the cylinders. The rest are fine and the cylinder with the scratch/groove is fine apart from that.

The scratch/groove only goes up just under an inch and the piston and its rings seem fine (will replace rings anyway). I can only think that there was some nasty little object flying about in the oil at one time.

Am I right in thinking this scratch/groove is below the piston rings on the lower extent of travel (it looks like that) and that it will continue to have no effect on the piston rings.
Iwan Jones

So long as the rings only come down well above the scratch it will give you no problems, it you feel like it give it a smooth with some emery. Well above = 5mm.
d brenchley

X2. RAY
rjm RAY

Wonder if these are crosshatch honing marks? They would have run the length of the sleeve and all that would be left would be the marks below the piston.

Bruce Cunha

A photo of the scratch and dimensions (dist from top of block, depth to bottom of oil ring etc) will help understand issue. Is it inline with gudgeon pin or spark plug? What is your piston to cylinder clearance? Have you considered teflon coated piston skirts if excessive?
Mike
Mike Ellsmore

x3. if it does not interfere with rings, no problem.
G
Graham Moore

This thread was discussed between 14/12/2016 and 18/12/2016

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