ADO16 1275 Engines

[Supersonic]

In the excellent book the Story of the BMC 1100 Steve Lee writes the following in the chapter about 1275 Engines fitted in the ADO16:-

“In early Mk2 cars from June 1967 a 1275cc engine was offered as an option to the 1098cc engine. This engine, suffixed by engine number 12G, is an extremely rare unit. These engines have double valve springs on the cylinder head and have a smaller 1.625 inch connecting rod crankshaft diameter also used in the Mini Cooper S. Tappet chest covers were still present on this engine and it is possible that the crankshaft was made from EN40B steel as used in the Cooper S engine. The introduction of the 1275cc engine utilised a completely different crankshaft, connecting rods, camshaft and cylinder head compared to the 1098cc unit”

What Steve has written above is factual but why did he start with the Mk2 cars that had the 1275cc engine installed?

ADO16 cars were fitted with S type engines in early 1967 until the 12H 1275cc engine became available later in that year. In order for BMC to provide a 1275 cc ADO16 from early 67 they used the 1275 cc S type engine to provide the option of 1098 cc or 1275 cc engines. The first 1275 cc engines were suffixed by engine number 12G and indeed are extremely rare. These engines all had a 9 stud cylinder head, AEG510 cam, forged rocker assembly and the EN40B crank with smaller 1.5/8 inch journals, connecting rods, crankshaft diameter being the same size as the Cooper S engines. The cranks were all marked EN40B and dated. They also all used a single 1½ inch carburettor. This engine was only fitted to the very late Mk1 MG, Wolseley, Riley Kestrel and Vanden Plas which were called the 1275 model. These cars were built in late 1966 and early 1967 before becoming available in early March of that year. As Steve states in his book very early Mk2 cars did have the 12G engine.

To further complicate matters, in July 1967 the solid wall block appeared with engine number 12G with EN16T (12G1288) crank that had 1.5/8 inch journals. These engines were only used in the Riley and MG 1300. It is important to remember that the EN16T crankshaft out of this solid wall engine has a different centre main bearing width to the Cooper S engine.

It is hard to date when the 12H solid wall block lost the 12G1288 crank. This engine now gained the 12G1505 crank that became the normal run of the mill BMC 1300 engine used in all ADO16 1300 cars and 1275 GT Mini from 1969.

The 12H 70 BHP engine is a sister of the above and had the 12G1683 EN16T crank with 1.3/4 inch journals, stronger connecting rods, high compression pistons and large valve 11 stud cylinder head. These engines date from about September 1967 and were only used in the Riley 1300, MG 1300 and Austin / Morris 1300 GT. I have one of these engines dated October 1967 and the MG 1300 it came out of was first registered in September 1968. It is worth saying that much as the 70 BHP cars arrived in the showrooms in September 1968 these cars were first built in early 1968 and production of 70 BHP engines must have started in the last quarter of 1967.

Some believe overseas cars had these upgrades earlier than the home market which may be correct from what we have seen over here

Mk1 1275 models were built in very small numbers and are very rare. A family friend has a peat brown 1967 Vanden Plas 1275 from new with 24,000 miles on the clock. The original bill of sale is dated very early April 1967 so the car must have been built in the first quarter of 1967. The danger with this car is some head case will buy this beautiful rare low mileage car for the engine to clone another fake Mini Cooper S

Alan

[JC T ONE]

A family friend has a peat brown 1967 Vanden Plas 1275 from new with 24,000 miles on the clock.


The danger with this car is some head case will buy this beautiful rare low mileage car for the engine to clone another fake Mini Cooper S

Alan

Nahh - who would do a thing like that just dont sell it to some one with the initials GH.

[david ado16.info]

That's fantastic Alan.....the only thing I would say is that I have never been aware of the 1275 option for the Mark I Wolseley.

Is there any sales literature, or price lists that show any of the options for any of the ADO16's - do we know of any Wolseley examples?

[Supersonic]

That's fantastic Alan.....the only thing I would say is that I have never been aware of the 1275 option for the Mark I Wolseley.

Is there any sales literature, or price lists that show any of the options for any of the ADO16's - do we know of any Wolseley examples?

Hi David,

It is funny you say that about the Mark 1 Wolseley. All the Mk1 1275 cars I have seen were MG, Riley and Vanden Plas. Paddy Gordon has sales literature for the Wolseley 1275 that I plan to copy at some stage. I'm trying to get all the information pulled together about all the engines used in the ADO16 for your new venture that we can do a feature about. It would be nice to get our overseas friends to add their knowledge to this discussion before we feature it.

What do you think?

Alan

PS There is a White Mk1 Wolseley 1275 in the South of Ireland that visits Kilbroney every year according to Paddy Gordon

[david ado16.info]

Hi David,

It is funny you say that about the Mark 1 Wolseley. All the Mk1 1275 cars I have seen were MG, Riley and Vanden Plas. Paddy Gordon has sales literature for the Wolseley 1275 that I plan to copy at some stage. I'm trying to get all the information pulled together about all the engines used in the ADO16 for your new venture that we can do a feature about. It would be nice to get our overseas friends to add their knowledge to this discussion before we feature it.

What do you think?

Alan

PS There is a White Mk1 Wolseley 1275 in the South of Ireland that visits Kilbroney every year according to Paddy Gordon

I think it's a fantastic idea Alan - really fantatsic

Mark might want to add such a feature to the MK1-Performance-Conversions website (we are talking Mark I after all ) but it really does deserve a place on the ado16.info website. Certainly through our FB group I am aware of an MG in the US but we've never asked about more - of course, when you're ready we can ask, also in our newsletter and magazine.

So, you need to send Paddy on a hunt with camera and note book - if there's a brochure and potentially a car, which we can verify through VIN and engine numbers then we may have discovered something very special.

[david ado16.info]

....actually I have pictures of a Vanden Plas Mark I with 1275 conversion, and come to think of it there's a black MG somewhere in the UK near Reading

[Costafortune]

What Steve has written above is factual but why did he start with the Mk2 cars that had the 1275cc engine installed?

The 1275 became available normally with the Mark 11 cars (1100/1300) in Aug/Sept 1967, solid block, single carb etc. The 1275 option arrived with the last year of the Mark 1 (Midget tail lights). I bought a rotten E registered 1100 VdP with the 1275 engine and the slanted 1275 boot script, a Mark 1 car. IIRC, it had the solid wall block derived from the Midget engine. No idea what crank it had but i'm 99% sure it had an 11 stud head. That was 1984 and I didn't use the engine, selling it for £150 a few years later.

BLMC were building engines from whatever they had and I don't think there is a hard and fast rule over what cars had what engines or gearboxes around 67-69. It wasn't unknown for a very early 1275GT to have an 11 stud head. When you think the Mark 1 Escort of that period had an 1100, a 1300, a 1300GT....all from the same block. No wonder BL went bust.

[Supersonic]

What Steve has written above is factual but why did he start with the Mk2 cars that had the 1275cc engine installed?

The 1275 became available normally with the Mark 11 cars (1100/1300) in Aug/Sept 1967, solid block, single carb etc. The 1275 option arrived with the last year of the Mark 1 (Midget tail lights). I bought a rotten E registered 1100 VdP with the 1275 engine and the slanted 1275 boot script, a Mark 1 car. IIRC, it had the solid wall block derived from the Midget engine. No idea what crank it had but i'm 99% sure it had an 11 stud head. That was 1984 and I didn't use the engine, selling it for £150 a few years later.

BLMC were building engines from whatever they had and I don't think there is a hard and fast rule over what cars had what engines or gearboxes around 67-69. It wasn't unknown for a very early 1275GT to have an 11 stud head. When you think the Mark 1 Escort of that period had an 1100, a 1300, a 1300GT....all from the same block. No wonder BL went bust.

You hit the nail on the head alright, from early 1967 to late 1968 the ADO16 had so many different engines over that period. You are correct in that the last of the Mk1 1275cc cars had solid wall blocks. These engines were known as 12G and used the 12G1287 or 12G1288 crankshaft that was EN16T tuftrided with 1.625" diameter big end journals. This engine found its way into to early Mk2 up market ADO16 cars. Only the early 1275cc Mk1 cars had the S type block with the AEG479 EN40B nitrided crankshaft. We have for some years now been researching this to attempt dating changes but this seems to be impossible from what we have found. Having worked at BMC / BL cars for over 40 years I have seen all the different engines in original cars but dating when they were built is another thing altogether

Alan

[Supersonic]

What Steve has written above is factual but why did he start with the Mk2 cars that had the 1275cc engine installed?

The 1275 became available normally with the Mark 11 cars (1100/1300) in Aug/Sept 1967, solid block, single carb etc. The 1275 option arrived with the last year of the Mark 1 (Midget tail lights). I bought a rotten E registered 1100 VdP with the 1275 engine and the slanted 1275 boot script, a Mark 1 car. IIRC, it had the solid wall block derived from the Midget engine. No idea what crank it had but i'm 99% sure it had an 11 stud head. That was 1984 and I didn't use the engine, selling it for £150 a few years later.

BLMC were building engines from whatever they had and I don't think there is a hard and fast rule over what cars had what engines or gearboxes around 67-69. It wasn't unknown for a very early 1275GT to have an 11 stud head. When you think the Mark 1 Escort of that period had an 1100, a 1300, a 1300GT....all from the same block. No wonder BL went bust.

You hit the nail on the head alright, from early 1967 to late 1968 the ADO16 had so many different engines over that period. You are correct in that the last of the Mk1 1275cc cars had solid wall blocks. These engines were known as 12G and used the 12G1287 or 12G1288 crankshaft that was EN16T tuftrided with 1.625" diameter big end journals. This engine found its way into to early Mk2 up market ADO16 cars. Only the early 1275cc Mk1 cars had the S type block with the AEG479 EN40B nitrided crankshaft. We have for some years now been researching this to attempt dating changes but this seems to be impossible from what we have found. Having worked at BMC / BL cars for over 40 years I have seen all the different engines in original cars but dating when they were built is another thing altogether

Alan

I should have said some people in the Mini Cooper Register claim they can date BMC changes which amazes me to be honest

Alan

[NZmember]

Alan
You mention the use of 'S type block with the AEG479 EN40B nitrided crankshaft' but what about the AEG577 crank in the MG1300? I posted a question years ago as someone in NZ was selling a solid wall short motor that he reckoned had an EN40B crank. From the pictures I found the crank had the number AEG577 cast onto it.


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