carb fixings

[Fortyfiver]

Can someone tell me if the carbs are rubber mounted as I seem to have movement when pushed, thanks
Alan

[mole42]

No. They are firmly fixed to the inlet manifold. Any movement might mean that the centre fixing is loose, which might mean that the 'O' ring is perished.

[Lingen]

Alan.
Or that the thread holding the pedestal fixing stud into the manifold has stripped so it can't be tightened. It isn't a major problem if it has.
Mike.

[dasadrew]

That's interesting - I can feel a slight sponginess on my carbs too. Everything is tightened down, no stripped threads etc. I was under the impression that it should be that way so that the carbs were isolated from engine vibration or temperature? Other carbs I know have a plastic "insulator" for that purpose.

Drew

[Budgie65]

My inlet manifold has a small down type pin on the outer edge of the circle which lines up with a hole in the base of the carburettor manifold, however there is still a very small amount of movement. I will try and load a photo if I can.

[dasadrew]

Exactly! This is why I was led to the belief that the carb sits on the squashed O ring and can move slightly but the pin stops it all from turning.

[MandM]

Exactly! This is why I was led to the belief that the carb sits on the squashed O ring and can move slightly but the pin stops it all from turning.

+2, very slight movement, as said it sits on a O ring, if it doesn't move maybe the O ring is flat and not sealing 100%, not all O rings are the same!. best to take it off and fit a new seal/O ring.

[NeilR]

+3, it should rotate slightly but not rock in any direction.

Neil.

[dasadrew]

sounds like if the carbs have no slight movement then the O ring might be at the end of its useful life?

[MandM]

sounds like if the carbs have no slight movement then the O ring might be at the end of its useful life?

or the wrong thickness!, you should also have a fibre washer at the top under the nut.

[dasadrew]

or the wrong thickness!, you should also have a fibre washer at the top under the nut.

Yes - the good old "Nearest Metric Equivalent" syndrome!

[Fortyfiver]

Thanks for the reply’s i can twist them slightly but not rock them so it sounds they are ok
Thanks Alan

[jbuckl]

Carb pedestal has to be in contact with manifold.
Oring is only for sealing. Roll pin is a locator.
any other arrangement will allow the nut to come loose& or an air leak.

[Davo1805NZ]

I'm at the stage of re-fitting the carbs on to my rebuilt engine and find that the pedestal O ring seems to be too small - it won't sit in the groove while I drop the carbs on to the stud. I did some searching on the Forum and read in another thread a suggestion for how to fix an O ring which had become too big - does anybody have a fix for one which is too small? Thanks in advance for any advice.

[Lingen]

Dave.
If it is much too small, I would buy a correct size one from a supplier who takes the trouble to stock them! Otherwise a bit of gasket sealer might hold it in place while you replace the pedestal.
Mike.