Fitting 1948 Es2 engine in wd16h

I am toying with the same idea with a 1948 M18 engine. The crankcase will fit as fixing bolts are in the same location. With the barrel, head and rocker box loosely assembled on the crankcases in my Wd16H frame I found there is just enough space below the top frame rail. But there is not enough clearance to fit all the rear rocker box bolts. Unless you come up with an ingenious solution to that, the fully assembled engine would have to be installed in frame. That might not be a problem but if you then need to access the valves or rockers the engine would have to come out of the frame!
Good luck
Nick 

Norton actually hastily put together a small batch (around 90) of these in late 1939. They were 1938/39 pattern Model 18 engines in a WD16H rolling chassis (the 1" lower frame).

Dave Graham has built a replica and I recall him saying that it is very tight at the back. He may also have mentioned that the rocker box castings of the 1946 engine differ slightly from pre-war.

I have a note from Peter Roydhouse in which he mentioned that all the OHV engines will fit, with the exception of the Model 19. Bearing in mind how tight the 19 is in the civilian frame, this is not surprising.

steven,
i have a 1936 frame with a 1954 model 19 engine,been using it for 15yrs,i have on occasions changed it for a post 1948 es2 engine,both engine go in the frame with no issue,s,
to remove the rocker box you need bolts rather than studs and nuts,if you remove the head bolts 
its possible its possible to remove the head and rocker box together,
                                                                            hope this helps,

On my '52 ES2 I have to remember to fit the rear two rocker box bolts into the holes before fitting the rocker box - there's not enough room under the top tube to fit them after the box is on.
John
 

Hi Anthony.
Good idea about removing the head and rocker box as a unit. I had not thought of that.
Thanks, Nick