Morris Minor Owners Club

So I pulled the head off my moggy today (1965 1098cc), forgotten how easy these old cars are to work on...took around 25 mins tops....it took 2.5 hours to do the rocker box cover oil seal on a Clio 1.2 16v the other day!

Anyway I removed all the valves and fitted a new no.2 exhaust valve and was amazed that this engine has excellent valve guides and unworn rocker gear....the oil seal O rings were hard as hell though.

It was when I was lapping the valves in that I then remembered I haven't used my speed lapper for some 20 years (Ford 3.0 Essex engine) and all my suction cups were all split....new ones soon sourced though.

Now this car done 121k miles, & before stripping down had a copper head gasket and some very frozen nuts and studs.

From what the previous owner tells me and from bills & invoices the engine has had no internal work in since 1989.

On inspection the engine bores have traces of honing marks, no discernable wear lip on the bores, pistons have very little sideways movement & had very little coke on them and cleaned up in seconds. The previous owner owned the car since late 90k miles.

Now from working on old A series Mini's I always thought these A series had noticeable top wear by 40/50k and blocks were fairly worn out by 70k miles, but being an older design they will go on even when really sha**ed....this from working on 1275 GT Mini, a 1100 Clubman and a Metro Turbo all owned by my mother and all from very low miles.

From what I see on the pistons these are std size, with a mix of three grade 2 pistons and one grade 3 all marked MOWOG meaning an old pistons and all in std size, the rest of the markings are a mystery to me being M2007 N28 on the grade 3 and M2007 N31 on the grade 2's....and all facing front which is nice

I'm puzzled. I'm thinking that at some time a new engine must of been fitted but not a Gold or Silver seal as they are no traces of Gold or Silver paint anywhere.

I'm new to moggies so any comments welcome.

PS tried to post a picture but no luck

Head has 12G202 casting number which I think is a normal 1098cc head?

Engine code is 10MA-U-H162791 which is same as V5

The numbers 2 and 3 are the sizing numbers as the pistons were fitted by selective assembly (see wksp man section AAA.5).
I am pretty certain that the other numbers you refer to are batch numbers.
The head number (12G202) is standard for a 1098cc engine.
The engine number is also standard 1098cc and is not a silver or gold seal unit.
Phil

Thanks Phil, nice to know its all standard....it has been serviced every year from '89 regardless of mileage covered but puzzled by lack of wear..pleasently puzzled I should add.

It is unusual though for one piston to be a different 'grade' size to the others -in my experience they would all be the same . Perhaps that one piston has been replaced in the dim and distant past - but it's not anything to worry about. It sounds like the engine has been well looked after - oil and filter changed regularly as they should be. And if not used for 'short runs' then yes - they can go on for a very long time. Are you planning on looking at the big end shells while you are in there?

Pistons were graded according to the bore size so there could be grade 1, grade 2 and grade 3 pistons fitted to the same engine.
The corresponding bore grade should be stamped on the top of the block adjacent to the bore.
I would check all bore grading and piston grading and see if the bore and piston grading are the same.
Towards the end of BMC/BL - engines could be found with re-bored cylinders and even liners because of production quality control problems.
Phil

bmcecosse wrote:It is unusual though for one piston to be a different 'grade' size to the others -in my experience they would all be the same . Perhaps that one piston has been replaced in the dim and distant past - but it's not anything to worry about. It sounds like the engine has been well looked after - oil and filter changed regularly as they should be. And if not used for 'short runs' then yes - they can go on for a very long time. Are you planning on looking at the big end shells while you are in there?

Most likely will, she is dropping oil so new sump gasket required as a minimum so may as well take a peep at the shells.

.....at the moment I'm bolting her all back together in rain and gales with just an open car porch for cover and just popped back to the forum to check on valve clearances, I'm going to go 15 thou for both exhaust and inlet initially, then maybe go 12 thou on inlet once she has settled down a tad....a slack valve clearance is a happy clearance for me.

....rule of nine should do for clearances if I remember correctly?

[quote="philthehill"
The corresponding bore grade should be stamped on the top of the block adjacent to the bore.
Phil[/quote]


adjacent to the bore....my head in back on now....

Indeed Phil - but I have never seen a mix of grades in an 'unopened' engine.

bmc
Indeed if the engine is unopened you will not be able to see the piston / bore grades
On a standard engine I always found that 15 thou rocker to valve stem gaps was beneficial to running.
Phil

Just been looking at the photos of the block face I took....didn't notice them before, but yes the block is marked on the nearside outside of the studs, I missed them the first time of looking.

....the numbers are three grade 2's and yes one grade 3!

I suppose it's actually a backhanded compliment to the person building the engine that the individual bores were indeed measured and a suitable piston fitted, and not assumed off of one measured bore.

.......on the flip side, the guy on the boring machine/honer had a bad day

Good research - well done !