Anyone familar with the Enfield flat twins?

I just bought a HO2 MK IV diesel at ebay, it'll probably arrive in a week or two. It'll be my first of these, I like their general appearance and all the aluminium. Sandblasted, clearcoated and accentuated with a satin black frame and airfilters etc, I think it'll be a very nice display unit.

As I've found out, there's a lot of varieties of these. Another nice one I saw was designated H1O 100 MK II. Almost identical in general appearance, from the pictures it had some differences in the airduct castings around the heads and cylinders.

Is there any litterature to be found, and what about parts interchangeability between the different varieties?

So far I've come across the one I bought which I expect is to be found in MK I through IV, the H1O 100 which I also believe has 4 generations I-IV, some are called HO2 85 from what I've seen? and it's all a bit confusing.

So in short I would love a few simple pointers as to what to look for and what to avoid for spares, spare engines etc.

Any help appreciated, thank you.

Hi and a very warm welcome to the forum. Good luck with your project. Post a few pictures in New Projects/Restorations once you get going.
I'm afraid I can't help with manuals but no doubt someone here will have suggestions. Have you tried here ? enquiries@vintagemvmanuals.co.uk

I think the HO2 85 is a slightly smaller capacity (and power) than the HO2 100 so some parts will not be interchangeable between these two engines. I'm told that these engine are technically challenging to work on, critical tolerances etc, so you will definitely need a manual for the engine. Check for matched pumps and injectors in the first instance.

Thanks a lot guys. Yes all I found regarding litterature online was a scan of the instruction book/service manual for the "Model 85 MK IV" over at oldengine.org. It might help some, but I would of course prefer a booklet for my exact model. Perhaps something shows up at ebay. As with every new acquaintance it takes a while to get familiar with them, and in this hobby that's a part of the fun I guess.

I just finished an AS2 diesel and a US-built DeVilbiss 445 compressor I intend to put on a frame as a diesel compressor set, it's just the finishing touches left. And when this nice little aluminium flat twin showed up I couldn't resist it.

As for mechanical complexity I just hope I didn't get in too deep, matching injectors and pumps sounds like something my guy at the local diesel shop will have to handle.

Regarding the HO2 MK IV and the HO 100 MK II, would they be differently sized, or is it basically the same engines with a major design update - or another intended end use - that justified the different designations?

Thanks again guys, much appreciated.