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Piston Rings - A-Series 998 Engine - Help Required

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#1 WanaGo

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Posted 18 April 2024 - 07:59 AM

Hello,

 

I have an A-Series, from a 1978 Morris Mini 1000, which I am doing up, and looking for help to ID what rings are required.

I am still to take it fully apart, to determine if I just need STD, or oversized rings etc, but I am having trouble figuring out what type of rings are even required.

 

The engine is not original to this mini I don't believe, however from what I have been told it is of similar era, and is the same size as what was in there. Its a

 

The block number on the back is: 12A 947
The engine number tag is: 99H353E-HI70073
 

The pistons are dished, and are stamped on the crown with M2039, FRONT and the number 42 (see picture)

 

Is anyone able to help identify the pistons, to then help identify the type of rings that are required?

I have asked Minispares, but they don't have this on file and referred me to this page 

https://minispares.c...es.aspx?1~2~103

 

Likely needing to take the rings off and measure them.

 

If anyone is able to help, that would be appreciated.

 

Pics of the engine with head off also included, when we were taking it out of the mini a few days ago.

 

Thanks in advance

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#2 DeadSquare

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Posted 18 April 2024 - 11:18 AM

Run your finger up and down the top 20mm of the bores to see if you cab feel a slight ridge in the metal, and I don't mean feeling the carbon that accumulates above the top ring travel.

 

As a rough guide, if you can't feel a ridge, there won't have been enough wear to require new rings, if you can feel a ridge, the engine needs to be re bored.

 

A company called Cord used to make excellent rings, for "Hard to decide if it is bad enough for a re bore", but I haven't seen them recently.



#3 GraemeC

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Posted 18 April 2024 - 03:11 PM

Quick Google for M2039 leads me to think they are a standard 998 piston.



#4 WanaGo

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Posted 18 April 2024 - 08:52 PM

Run your finger up and down the top 20mm of the bores to see if you cab feel a slight ridge in the metal, and I don't mean feeling the carbon that accumulates above the top ring travel.

 

As a rough guide, if you can't feel a ridge, there won't have been enough wear to require new rings, if you can feel a ridge, the engine needs to be re bored.

 

A company called Cord used to make excellent rings, for "Hard to decide if it is bad enough for a re bore", but I haven't seen them recently.

 

Thanks for the reply.

Yeah I cant feel a ridge itself, but the bores definitely need a bit of a tickle up with a hone I think. There is a weird sort of ridge on one side but this may just be carbon.

Given the age of the engine, I was thinking of hone and then new rings, just to give it a new lease on life really. But if the rings are likely to still be totally fine, then I can just reuse them I guess. Just through I would refresh it a bit while I am in there anyway.

Once I tear it down, and if I find a broken ring or something, then yeah - still unsure what type I need to get to replace it. I did google M2039 but found very little and nothing giving information on what I was looking for.

 

Few more pics

 

Thanks

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#5 sonscar

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Posted 19 April 2024 - 10:29 AM

Not an expert,but that looks too late for a hone and rings.Has it been sanded down as the scratches appear to be round and round rather than diagonal.Steve..

#6 WanaGo

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Posted 19 April 2024 - 10:47 AM

Unsure of the history. I drove it into the garage off a trailer, had no brakes. Started up instantly and ran well. Had been sitting for 20 years off the road. Took engine out and head off and this is what I found. I don't know the history.
The vertical scores almost look like it got rather hot at some stage. Not surprisingly none of the marks catch your fingernail really.
I'll know more when I take it apart I guess.





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