Converting back to original engine + gearbox

[MaltaMM]

Hi All,

I am new to this forum. I am an old car fanatic based in Malta, with my main interest being Morris and Austin models. I have a 1967 Morris Minor pick-up with the Maltese style box and a 1952 Morris Minor series MM.

Over the years my MM was fitted with a 1275cc Marina engine mated to a Morris 1000 gearbox. Although this set up has made the car very useable, I am toying with the idea of converting it back to its original engine and gearbox (When I find them that is!). I have obtained a British Motor Industry Heritage Trust certificate for my vehicle and found out that it was originally fitted with the USHM3 sidevalve engine.

The Marina conversion was done some years back by a previous owner. Can anyone tell me what the converion back to originality would involve. Do you think that (apart from the floor where the gearlever protrudes) the body / chassis was modified in any way for the conversion and what should I look out for? I would appreciate any comments which would help me to bring my car back to original specification and also any leads to finding an original USHM3 engine and gearbox.

Thanks in advance,
Kind Regards,
Stu.

[RobThomas]

They'll have cut a knotch out of the underside of the crossmember where it goes over the gearbox. Almost everything else is the same. You'll need engine, box, propshaft (Hmmmmm, maybe not?), starter, exhaust manifold (different bore and angle) and I expect the clutch linkage is quite different since the MM uses a flat piece of sheet steel as a link.
USHM3 engines are the sidevalves with the waterpump option on them so it is possible to locate a Centurion Tank donkey engine from a museum for the conversion. A complete Morris 8 (pre Series E, so pre 1945) would give you almost all of the parts for a cosmetically acceptable change although the engine is weaker and less powerful.

[RobThomas]

PS I have a Morris 8 engine/box in my 1935 MG pick-up (Doooooon't ask!) that was replaced by the MM as the tow-car for the aeroplane.

[mike.perry]

It very much depends on how far the previous owner went with the conversion. Has it still got the original rear axle? If so then it will have Series MM wheels which have 3 studs to hold the hub caps and a hole to adjust the brakes.
Depending on the time it was built in 1952 it will have either the early straight engine bay cross member or the later curved cross member which was designed to take the A Series engine. The floor pan behind the gear lever will have been cut away to fit the later gearbox and it will have the later gear box cover panel.
To convert it back, you would need beside the engine (USHM3), gearbox, propshaft and possibly rear axle, front engine mounting towers and rear gearbox cross member.
There are also engine and gearbox mounts. For the engine mounts you can use M1000 gearbox mounts.
Nearly forgot about the radiator and hoses, C39 dynamo ad probably a lot of consumables.
The clutch / brake pedal et up is different in the Series MM, they are both inside the chassis and the linkage is different
The same starter can be used provided it is a normal Morris Minor type and the exhaust is the same from the silencer back. Don't forget the carb and manifold and the distributor although an A Series dizzy will fit an MM engine

[rayofleamington]

in the Series MM, they are both inside the chassis and the linkage is different

Series II pedals are also inside the leg - so is it only the linkage that will be different?

[mike.perry]

Can't claim to have ever inspected a Series II clutch linkage so I will have to pass on that, although as it has an A series gearbox I would expect the linkage to be A Series.

[MaltaMM]

Thanks for your interesting replies, they will certainly help me when the time comes to fit the original engine and gearbox!

The previous owner seems to have restricted the conversion just to the engine and gearbox, as the car still has its original rear axle and Series MM wheels. The handbrake is also the original, in fact it its impossible to release the handbrake when the car is in reverse gear!

The radiator is the normal Minor 1000 type so as has been mentioned the front panel has been modified from behind.

My MM was built in October 1952 so I assume that it was originally fitted with the curved cross member which was designed to take the A-series engine. If this is the case, at least that will be one less item to source!

Stu