So far, both E29s I have looked at with diesels have required a modified engine cover to provide clearance for the taller (than original A-4) engine. This surprised me since several makes (Universal, Beta) market their engines as A-4 drop-in replacements. One boat has a 4 cyl Universal (FWC) rated at 25hp, the other a Volvo MD6b (RWC) at 10hp.
I am considering the boat with the MD6B, and although the engine is reported to run ok, if I do need a replacement, I'd prefer to return the engine cover to its original design. Does anyone have a diesel in their E29 with original engine cover? Is it fresh water cooled? Was the A-4 mounting in the E29 unusually low profile? Or did the two boats I've seen just end up with whatever engine was available for cheap, and the resultant hacking of the engine housing?
Thanks!
Usually the most difficult part of an engine swap is fabricating new mounts, especially if the bed logs (i.e. glassed in wood or metal uprights) are very much different than the factory positioning.
Building a solid mounting for the new engine's mounts can be a time consuming part of the work. A friend of mine changed from an ancient German V-twin diesel to a new Yanmar.... and both of us still chuckle at the memory of him down there under the companionway with a power planer producing a wonderful inches-deep pile of mahogany shavings around his feet when I looked in on him!
(This was an early Cascade 36, FWIW)
The room for an overhead-valve engine, like most modern diesels is the next challenge in changing from a flathead gas engine like the A4. Owners of 70's Ericson's and a herd of Catalina's with the horizontal-single-cylinder Yanmar diesels have similar stories of dealing with the extra height of new diesel engine designs when they replaced their original engine.
Note that unless you reconfigure the shaft log (Oh My... that's way above my skill set) you are going to have to align that new engine with the existing shaft. That will dictate where the mounts have to go.
Check my photo in my blog here for the pattern in place for our new Betamarine last year. Lucky us, only the height and angle had to be slightly accommodated for the new Beta engine.
BTW, some parts of your narrative puzzle me. I am not aware of Universal building a 25 hp four cylinder diesel. Their most common older design was a 21 hp three cylinder and a lot of those were factory installed in early-80's Ericson's. Our boat had the later-80's iteration of that engine, a 23 hp three cylinder engine.
Regarding the boat with the Volvo, I admit to never owning one, but all the mechanics I know dislike them passionately. OTOH, having said that, the early single and twin Volvo's do have a reputation for long life, with the caveat the parts (when needed) are more expensive than for most other similar engines. And, further caveat.... any (!) small diesel from the 70's is likely to parts availability challenges going forward. Even the very-reliable Yanmar YSM series will invoke some serious challenges nowadays seeking parts.
Regards,
Loren