classic motorcycle forum

Yes I think it might be complicated, not helped by the fact that the 147 and 196 used different inlet manifolds. https://www.barnstormers.co.nz/wp-content/uploads/2020/04/Coventry-Manual.pdf

If there's room, the bike would probably run with a "stub" manifold and the carb hanging out the side. This could be made pretty easily. But in the meantime you need a good illustration and some measurements of the correct part so you can show people what you are looking for. I have a couple of unidentified cast 2-strake inlet manifolds in my junk box, but I have no idea what they are off. Now that I've looked, not 1932 CE, I think!

Cheers

Leon

A simple tubular stub - to suit the carb, and a 2 bolt plate welded on would about do it. ?

You might need to carefully consider the angle of the inclined cylinder,
best so that the carb is quite horizontal.
And the weld likely needs to be gas-tight.  Well within the skill set of most welders...

I recently came into possession of a 1932 Coventry Eagle Silent Supreme that has the Coventry proprietary engine.  Sadly it's missing the intake manifold. 
Does anyone have a clue where I might find one?
Thanks

I have a new thought that fits in well with this old thread...

During the week a friend showed me photos of an "unidentified" frame, which the owner sort-of-thought was Excelsior but maybe not. It certainly looks Excelsior, style-wise, but the unusual feature is a "double tube" arrangement to support the tank. I went to my magazines but couldn't find a mention of this feature, which is presumably around 1923-24 since the final drive is by belt. For 1924 there were a couple of barely-mentioned models that are contenders: a 247 Villiers and a 250 (not the long-standing rather boring 293) JAP. My guess is that it is one of these. (Apparently Blackburne engines that came with the bike were clearly too large...)

I found one photo of a surviving Excelsior with a 247 Villiers https://www.carandclassic.com/car/C1468206 and I fancy I can almost see the front end of the "double tube" arrangement under the tank. Tank, fork etc look identical.

Can we verify that the "double tube" is an Excelsior feature? The frame is Excelsior 247 Villiers 1924? A couple of years later the Excelsior Minor (see above) used much the same layout, but with the 147 Villiers and a funny front fork  [edit: but without the double tubes].

Cheers

Leon

Even making your own nuts can become expensive nowadays. Sourcing Whitworth hex bar can be a drama and you have to decide between 26tpi carbon steel taps or high speed steel jobbies. Having long since built a good workshop range of 26 & 20 tpi taps I'm okay but I'd hate to be starting off now. It's great once you're set up but taps can get pricy if you don't watch out. I think I haunted every second hand tool merchant and machine shop clearance sales for years to get some of the more obscure sizes. Some of the various 1" plus 20tpi sizes for old fixed head side valve engines were a real find.
Any way, go to it Murdo. you'll be surprised how often having a tap of the right size gets you out of trouble. Just make sure you have dry long term storage for your hex bar.