What I (think) I know:
They were part of the 375/425/602 family, I believe producing 26BHP?
They don't have an oil cooler
Fitted originally to the Ami 6

What are peoples experiances? What's maintenance like?

sam,
cold weather must be having an adverse affect on your memory banks.
Reckon you meant oil filter...

I've got three M4 engines here, plus boxes of bits for them, all the property of Jim Rogers.
I'm supposed to be putting together at least one usable engine, maybe two with a bit of luck.
I'd reckon that the lack of a filter is their achilles heel, judging by the box with 3 scrap crankshafts in it, other than that they're much the same the later engines, except that many of the main components aren't interchangeable with the equivalent part in later engines.

ken.

But if Sam looks after Hetty and does regular oil changes, he'll be ok right?

Am I that obvious?

yeah, you are

how easy are rear ends of vans to put back together as people seem to like rear ending sam?

I'd hate to upset anyone but if an M4 went wrong, it would, if you had to, be poss to slot an M28 in right?

No sadly, the positioning of the exhausts gets in the way of the pedal assembly.
I have a friend who rebuilt an M4 using the bottom end of an M28 though

Jozefs ami6, the channeled one, has an m28 bottom end with m4 heads. Apparently quite an easy thing to achieve, and looks pretty good.

I need to avoid taking it from behind in a van really n



Really? Daras Rich's 350 has a similar satup

It isn't that hard to do, bit of messing with the exhaust but in essence it'll bolt in. The basic difference is that the M4 uses a different manifold to the M28. The flanges are horizontal rather than angled.

The M4 uses a single barrel carb, and the throttle is pushed by a rigid rod. The M28 has a double barrel carb and the throttle pulls on the linkage with a cable.

You therefore either need to swap in a late throttle pedal assembly, or make some sort of lever arrangement.

As to the exhaust you swap the swan neck from left to right. Yopu cut the long pipes off the transverse silencer, cut off the mounting brackets and turn the silencer back to front. You then weld the long pipes back on. Cut the swan neck in half and mirror image it' do the same with the tail pipe. Doing this will allow a modern zorst to clear the chassis mount master cylinder.