classic motorcycle forum
Motorcycle Discussions => British Bikes => Topic started by: ramwing7 on June 16, 2026, 03:06:55 PM
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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
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Something like this - a Silent Superb ?
(it was unclear if this was that actual version).
That manifold doesn't look very complicated ?
(https://cybermotorcycle.com/marques/coventry-eagle/inc/Coventry-Eagle-1932-2-2.jpg)
Short of endlessly trawling fleabay, or approaching Villiers Services for one, maybe the local fabricator could whip one up ?
A simple tubular stub - to suit the carb, and a 2 bolt plate welded on would about do it. ?
I had a manifold made up for an Enfield project. They used a long-necked Amal, which are near impossible to find as the correct one.
Wasn't especially expensive - and I had it done in stainless, so was a real work of art.
A plain steel one would not be beyond most workshops.
And if its all thats stopping you going for a ride. !
Be thankful its not the exhaust thats missing. Now that does look special. !!
Good luck, keep us posted..
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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...
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Or does it have one of those curly-whurly alloy thingies - to the other side ??
That makes it somewhat more complicated ...
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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
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You guys are spot on with the pics. I expect I'll have to fabricate one. Might go so far as to try fabricating a model and the sandcasting one. Although welding one up is starting to appeal to me as well. Expecting a few false starts, but that's why we work on these old things. Right?
But, if you have one around and have some time for measuring, I would appreciate any help I could get.
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If you want a really good picture of an original manifold, 'The Vintage Motorcyclists' Workshop" by Radco contains a full double page photo of his restoration of the same model. Pages 180 and 181 to be precise. Its a photo of the timing side so gives you a good view of the manifold.
Radco also wrote a fairly extensive article on restoring the engine for the Vintage Motor Cycle Club Journal. This would be back in the late 70's. early 80's as his book was published in 1986 and was mainly a compendium of all the restoration articles he had written for the Journal over the years.
He wasn't complimentary about the engine but I think anyone trying to beat Villiers at their own game back in the early 30's would have had a tough job. In the end Cov Eagle came back to the Villiers fold. They made a better and cheaper product.
All that aside I think looking at 3D printing is the way to go. I've made one batch of inlet manifolds. Made the patterns, got them cast and then machined the result. It is not as simple as it looks. Making a pattern the foundry was happy with was a learning curve in itself but the big pain was making a range of jigs and fixtures to hold the castings so I could machine them afterwards. Not as simple as it looks. I realised early on that making a batch was no harder nor dearer than making one so a batch it was. No one was interested in my efforts nor wished to help nor put money in until I appeared with the completed batch when desperate owners needing one just appeared out of the woodwork. All the extras went amazingly quickly.
It's 3D printing for me nowadays and that is more involved than you expect.
Have fun.
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'The Vintage Motorcyclists' Workshop" by Radco contains a full double page photo
Split across 2 pages it must be noted. The manifold is slap bang in the page join !
All the online scans are awful in the picture dept, they must have scanned a photocopy
I've done some lost wax casting.
Doing a curly plaster central core of the actual gas pathway and coating it with wax to a suitable depth and then coating the whole
shebang in more fireproof plaster is possibly the simplest method ? You'd have to find a foundry that does this type of casting.
Simpler than it sounds, and cheaper as a one off than making moulds and core moulds.
The cast metal very accurately replicates the finish on the wax - so you could inscribe your image on it !
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Thanks folks. You have to love the vintage motorcycle community. No matter how unusual the bike is or how strange the problem, somebody out there has ideas and tips they are willing to share.
I'm off pursuing some of these now.
Thanks.
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Villiers loved those curly-whirly manifolds.
Keep your eyes peeled, this one is about the exact mirror image ?
Good luck.
(https://images.auctionet.com/thumbs/hd_item_5128019_c94c1be9b6.jpg)
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Any idea which Villiers engine this is?
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8D or (more likely, based on numbers built) 9D.
Here are the Cov Eagle images 33D6 refers to, in Radco's book. 1933, 150cc. The inlet manifold looks even longer than the one posted above!
Leon
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You'll note also the Amal carburettor, not Villiers. These are fairly easy to find as it's more or less the generic Amal of the time for all the 150cc four-strokes made then. Royal Enfield, New Imperial, Excelsior, Triumph, BSA and so on. As the UK introduced a major tax break for up to 150cc machines in the early 30's, sooner or later every firm and their dog seemed to have a go at making a nifty 150. There's more survivors than you think but they all suffer the same equal restoration cost problem. It costs much the same to restore a 150cc bike as it does to restore a larger one so enthusiasts spend their money on the bigger machines letting the 150's gather dust. Pity about that. They make a refreshing change from yet another 500 sidevalve single.
The trick lies in finding out the jetting specifications and so on as it should be different from those used in four-stroke applications. I may have it somewhere but Amal carbs don't figure much in my world so I'm unsure.
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I also know nothing about AMALs, but here are the specs. Columns are: Type, Internal bore, Jet, Throttle valve, Needle position, Float chamber type, Special details
Leon
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We live in a golden age of information.
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How would an Amal off a BSA Bantam go ?
(Did we ask if the original carb came with this project ?)
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I have two complete carbs (Villiers) which came as a job-lot with my C-E.
Shame you lot are too far away..
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Where are you
Alaska
Tierra del Fuego
Siberia ??
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GB.
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Don't you live just around the corner from the OP ?
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Who knows?
Do you know Crocodile Dundee?
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Yes I saw him in the movies.
I doubt he knows much about CE's though ?