997cc Engine

[Ernie]

Hi, I have a 1962 Morris Cooper and new to the forum.As I am technically challenged please excuse my lack of knowledge.I am trying to confirm the engine is a 997cc, the engine number plate is missing, possibly lost during restoration.Is there a simple method of identifying the engine without measuring the bore and stroke. According to Parnell (the bible) the cylinder head should be numbered 12G202, would the cylinder head have been changed when converted to unleaded petrol? Does the engine block have a number etc. The mini came new to New Zealand in 1962 Many thanks for any advice.

[boxofbits]

Hi Ernie

If you look on the rear radiator side of the engine block I believe it should have '1000' cast into the block and 12A 204 below it. This would identify it as a 997cc engine. But it may be worth checking the head also.

You might need a mirror and a light to see it!

[Ernie]

Hi BoxofBits,
Many Tks for your reply and advice. Cheers

[mk1]

This is where you should be looking.

[Ernie]

Hi,
Many Tks for the diagram, that's great. Cheers

[251 ENG]

The 12A 497 block casting was used on later 997 ,s

But this is also the block used on early 998 and 1098 engines

[Ernie]

251 ENG,
Many tks for this info.

[woodypup59]

A 997 is a long stroke, torquey engine (bore = 2.47", stroke = 3.2").

An 850 has a similar bore but stroke of 2.7" so thats quite a clear difference.

Without taking the head off, I have measured the stroke on a built engine by poking a thin rod through the spark plaug hole and turning the crank, making marks on the rod as it goes up & down.

I don't know of a reliable way of measuring bore without taking the head off, and infact every engine size has slightly different bores - tho S's are diefinately larger.

Also get the head casting numbers and check here, Google or another mini website to check what that head fits.

The 202 head in standard form isn't that good. The valves are slightly larger, but are more shrouded, so power gains are marginal.

A 12 G 295 head is what you need, suitably skimmed to get the right CR.

[Ernie]

Hi Woodypup59,
Many thanks for your advice much appreciated. Cheers

[mk1]

If restoring / re commissioning a 997 Cooper engine slapping a 295 head on may be great from performance, but it ain't great for originality. It's better to get a 202 modified than put the wrong head on.

[251 ENG]

Early 997,s had a 12A 185 head casting

[Ernie]

Many thanks for your info. Its been great. Cheers