Hitchcocks Forum

I’m sure a bit of milling would cure this, but still...

I’ve remove it now due to high revving. Another throttle slide would be needed and buying this carb was a bit of a trial. Can’t really justify spending anymore at the mo.

https://youtu.be/94JOxmNh0dI



John

What is the black between the carb and the engine made of? Does it have too much give in it? What would happen if it were something harder?

From Amal website,

Tighten the mounting nuts carefully and evenly. Nuts and spring washers should be tightened until the spring washer is just flattened. Over-tightening the nuts will over-compress the flange gaskets at the flange extremities and may warp the flange, and in extreme cases the carburetter body, causing the throttle valve to stick.

Mark 1 carburetters are not designed to bolt tightly to the intake flange and may distort if overtightened. It is only necessary to compress the O ring seal to ensure air tightness. When correctly tightened the carburetter flange and engine manifold should be no more than just touching. Nyloc nuts should always be used to mount Amal Mark 1 carburetters

Every one overtightens every thing wich will distort the mounting flange . Milling is not necessary just file it flat and make a gasket.

You can just lap the gasket face on a flat surface if it's been warped (wet and dry stuck on a bit of plate glass).

The slide looks pretty scored on that video though, I wonder if the inside of the carb body is similar.

Thanks all.

Chris, they’re a couple of fibrous tufnol gasket blocks; brown in real life.

Haggis, good point. I’ve had many Japanese bikes and a number of BMs and Guzzis. Everyone has a rubber manifold.
I’m not an overtightener, new word, they were literally just ever so snugged, but I can see the point with the spring washer of nyloc.

Crossed over there stinkwheel. Might be the light, the carb is very clean and scuff free.

Anyway, it revved like a banshee. Bigger bore I know, but a smaller cutaway for the slide would help that.

It’ll sit on the shelf for a while now. Can’t really justify buying a slide just because starting with my monobloc can be a pain.

Even on a new carb I do not fit the o ring as soft as it is, as it sits proud of the flange it begs to be overtightened to close the gap ,it gets worse when the seal is old and hard,I just fit 2 gaskets with Wellseal on,they always then sit flat and do not leak

Colin

Have to say after many years dealing with soft alloy around BMW drain plugs etc, it really wasn’t tight. But obviously in this application, I’ll just make note of how little tension is needed.

If I do eventually buy a slide, then I’ll look at sealants as well.

That is weird.
It looks, to me, that the flange could be not as flat as it should be, not bowed in the usual 'overtightened' way, that just causes an air leak, not distortion. but either a casting fault or someone trying to 'lap it flat' badly, the result being that the centre of the flange is bulging out more than the stud hole ends, resulting in the slight distortion of the body causing it to grab the slide as you nip it up slightly.
Clean the flange, remove the 'o'ring and see if it rocks on some plate glass or a known flat surface.