196 super sport inlet manifold

[Vreagh]

I'm having a few teething problems with my 1930 Francis Barnet Black Hawk. It's proving difficult to tighten the Villiers carb onto the manifold. I had self amalgamation tape on originally but this  dissolves in the fuel. I tried a 1mm plastic sleeve which was too thick also .5mm thick shrink sleeving, also too thick. The manifold doesn't appear worn ( still has casting marks) but is around .5mm under size and the carb clamp can't close enough. Was there a .25 sleeve originally? Any suggestions gratefully received.         

[Rex]

Use a sliver of appropriately-sized shim stock?

[33d6]

As from the factory the 196 Super Sport had a Villiers Medium Weight (MW) carburettor. This clips on to a 1.125” machined mounting stub on the inlet manifold. The carb itself has several fine slits (usually four) in the clamping area allowing the clamp to squeeze it down on to the machined stub.
You have two issues here.
Firstly the manifold stub is worn out of round and under size. It is a machined surface and should contain no casting marks. I suspect those you describe to be wear and tear.
Secondly, the fine slits mentioned above will be closed up due to previous owners tightening the clamp more and more trying to take up the stub wear. You cannot clip the carb on firmly until they are returned to as made. It is no great problem to gently ease them back out to size again. I use a specially tuned solid steel stub for the job but the right size ball pein hammer should do just as well. Just remember slow and gentle.

When the carb is back to size you can start on the manifold. Perfection is a new manifold, been there done that but it’s a real pain no matter how you go about it. Secondly you can replace just the stub, turning up a new one to have it welded in place of the old. Also fraught with drama as welding new to old aluminium is a tricky business. Villiers did concede a sliver of shim brass as suggested by R as a temporary fix and basically that’s all you can do until you get a better one. Shim brass is available in many thicknesses so no drama .
You’ve already found out that plastics and such aren’t keen on prolonged contact with petrol. Brass doesn’t care that much

[Vreagh]

Thanks to both of you,  I'll try shims next then. Interesting that originally it was a machined surface, this one is definitely not that now yet is a constant diameter along its length.

[R]

In this neck of the woods, we have a chap who can reclaim about anything
using hard chrome plating - and grinding back to size.

Perhaps there is similar in your area ?
This can add quite some thickness, if necessary.
Quite economical too.

[cardan]

Aluminium drink can + scissors, with a smear of non-setting gasket compound.

Leon

[33d6]

I am curious. It wouldn’t be the first time I’ve seen a bronze Villiers carb seemingly bonded onto an aluminium manifold.  Aluminium  and bronze is not a happy electrolytic combination. Over a long period the aluminium corrodes away and sort of bonds into the bronze carb body. This is not really a problem as long as the joint isn’t disturbed and the owner treats both items as a single unit, removing both manifold and carb together and keeping them together but unfortunately this is a rare occurrence. They began life as separate items and the owner reasonably expects them to continue this way.

This may have been what’s happened here. It’s an ancient motor cycle, the manifold and carb have had a very long time together for electrolytic activity to occur, then along comes an enthusiastic owner who separates the two for cleaning and renovation finding the manifold “shrunk “ when  the corrosion is cleaned off.

The same problem remains. How to fix it. I tend towards permanent solutions. I really don’t like the bits of shim or aluminium can route. In addition to my two previous suggestions I’d consider a thin sleeve. Trueing up the current stub and the permanently fixing on a thin sleeve with Araldite or similar. This would all depend on how sturdy the original stub is when cleaned up.

[Vreagh]

I too worried about electrolytic action between brass and alloy so have ordered stainless shim (I never thought about a drinks can). This combination seems to work on marine equipment fairly well. I did notice in the kit of spares is a bronze manifold but this would seem to carry the carb at a odd angle but is worth digging out and checking again. Thanks all for your input, I now have a few avenues to try.

[33d6]

Yes, Villiers did eventually move to bronze manifolds. Seems to have started in the late thirties as I have 9D engines with brass manifolds. They last much better than aluminium but boy, are they heavy.

If I ever make any more they will be bronze.

[Vreagh]

Update in case someone else might find it useful.  I curled a 3/4" x 10" strip of 316 (a4) stainless into a 7" circle and wound it inside the carb. It's springiness held it tight to the outside and tried the fit, it was too tight so kept removing 1/2" of length until it was a snug fit. Carb is now tight with no air leaks and engine running sweet. Many thanks to all for your suggestions.

[R]

Get a pic ?

We are assuming this stuff must be mighty thin - shimstock ?

[Vreagh]

Yes shim stock, .1mm thick. Here's before and after pics, I didn't  want to repaint the tank because I'd lose that originality so have done little cosmetically on any of the bike.

[Rex]

Looks to be the same engine as my old Coventry Eagle had fitted.
I guess you'd need a pokey engine to drag that huge horn around...

[Vreagh]

I had to use the large horn so it could be heard over the exhaust.😁