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MG Midget and Sprite Technical - 1275 Piston identification

Hi all,

Just removed the head to search for the cause of high oil consumption.

All looks standard and original, however, just to confirm:- the tops of the dished pistons are stamped with - A M2210 W19

Assuming these are standard sized and low compression?

Regards, Tony

Tony G

They would appear to be standard size as they don't seem to be stamped with an oversize.

UK-spec cars were generally 'high compression' or 8.8:1
Dave O'Neill2

Unpleasant groove across the narrow space between the bores?
Lawrence Slater

Hi, thanks for that. Yes, no oversize marks I can see.

The "groove" between cyl. 3 & 4 is more of a mark, it does not catch a finger nail or leak between the cylinders.

regards, Tony
Tony G

Hi Tony,
Any evidence of where the oil on the piston tops was coming from?
Guy

Hi Guy,
When dismantled, there was evidence of a little oil in both inlets of the manifold and a 1p size pool in each piston dish. (even though I had just returned from a 50 mile blast) There was a smear in the timing-carbs tube too.

The valves & guides are new, so it must be rings, even though the compressions are 165 (dry) and 185 (wet).

Thinking about it, with the amount of oil running about in the cylinders, even when hot, dry readings are probably not so.

I guess blow-by is pushing some oil up the tube to the carbs.

Taking the sump off shortly, this will give me a chance to check the condition of the rings, although the bores are smooth.

The car is a 72 1275cc with 50k, however, its only done 2k miles in the last 20 years, some years only 10 miles between MOTs.

Keep you posted.

Regards, Tony
Tony G

Oil control rings sound like good suspects. Might be stuck in the piston grooves.
Lawrence Slater

This thread was discussed between 30/11/2011 and 01/12/2011

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