Single to double rib stepped rubber?

[Adam_Winstone]

Hi all,

Anyone know where I can source a stepped carb rubber that has the single lip on one side and sized to fit on a standard TS1 manifold/34mm Amal stub, with the double location rib for a 34mm VHSB carb on the other side? I note that you can buy a single rib (both sides) stepped rubber from AF (and others) or a stepped double rib item from MB, however, one suggests modifying the carb and the other recommends modifying the rubber, neither of which I really want to do if I don’t have to. Knowing how many people fit VHSBs to TS1s, surely someone has sourced these or had them made?

Anyone know where I can source such an item?

Thanks in advance.

Adam

[Captain Pugwash]

Ive used a double rib stepped rubber on mine and removed the ribs on just one side with a small tungsten and then used a mini flap wheel just to slightly clean up the cut, I never did find a stepped rubber that fitted both.

Good luck, Mark.

[Adam_Winstone]

Thanks Capt.

Given the choice I'd rather modify the manifold or carb stub, once, so that I can always source a spare rubber that would not need modifying to fit, rather than modifying replacement rubbers or spares every time.

I'm a little shocked if no one has had these produced in the period since 34 VHSB took over as TS1 carb of choice (AF) from the initial 34mm Amal spec. Plenty of people have looked to address the TS1 to 30 VHSH or 30 PHBH requirement (noting that these should not be considered the same) so it seems a little lazy/slack to not have addressed the TS1 to 34 VHSB requirement. I guess that it has been addressed... but more bodged than addressed fully/satisfactorily.

If anyone does know of such a rubber, which needs no modification (or to carb) then please let me know?

Thanks/regards,

Adam

[HxPaul]

Adam,I dont know if this is any use,but I was reading MB's Facebook page the other day and he had made some carb rubbers that stepped down/up which ever way you wanted to go.I dont know if they're double lipped or single lipped,or a combination of the two.

[Adam_Winstone]

Thanks Paul,

I've been very happy with MB's stepped rubber mounts for other carbs, his various manifolds too, but he doesn't seem to have quite what I'm after in this case. I may well give him a call just to make sure.

It seems odd that this should not be readily available as the VHSB range has been the recommended carb for over a decade!

Ta

Adam

[Warkton Tornado No.1]

Good Morning Adam

I’m not sure any of what I can add to this thread helps, but it is attempt.

The flexible ‘rubber’ connection of carburettor to manifold adopted by many of us is a great principle. That is, in practice, & not so easy to apply universally.

My garage/workshop comprises a host of manifolds & carburettors. I’ve witnessed the change from the solidly mounted Dell’Orto VHB & Amal Concentric Mk I to the Amal Concentric Mk II which spawned derivatives using the ‘elastic’ mounting based upon the Ø 34 mm bore.

Recent times have seen the Ø 38 & 39 mm Dell’Orto VHSB/C come into common use.

Never one to pass up a bargain, a couple of ex Motiv 38 mm VHSC’s came my way via a karter. They had been shortened on their spigots to suit the Rotax motors they were intended for. As a consequence, there wasn’t even the double step to contend with, but just the one remaining.

Try & find connectors to suit that! It was no longer the case of modifying the inlet manifold, so often the case, to suit the rubber, with addition grooves, or making a manifold from scratch.

Ultimately, I had to modify the best of the connectors I had to suit.

Shortening was not the problem to make a twin ‘ribber’ into a single rib. The problem was ensuring that once shortened, a decent ‘clamping on’ be ensured.

What I did was to mount the connector on to my pillar drill by pushing the unmodified end on to a suitable spigot, in the drill chuck. Making ‘rubber’ run true is a little tricky.....

Then, I was able to grind the outside with a Makita electric sanding file a groove below the original surface for a worm drive band (Jubilee clip) ensuring that there was an abutment so the band would stay put in situ.

That arrangement has worked very well. Carburettors mounted thus have never come loose, which is quite a claim in racing circles....

For your scenario, there may be little option other than find a connector that is undersize on its bore, then have it mounted, preferably in a lathe, & grind the bore & profile to that you desire. As long as you have high speed cutters (sanding drums work well) & a die grinder or Dremel type tool, the ‘rubber’ will machine up well.

Perhaps you may have little option than apply similar principles.

Best Regards

Mark

[Adam_Winstone]

Thanks for the response Mark, certainly food for thought.

Adam

[Dimitrios_231]

Hi Adam,
check if 131012B Malossi rubber can do the job that you want,
they say it is 40mm 1 rib/44mm 2 ribs rubber.

See their rubber list
http://www.malossistore.co.uk/Prodotto. ... 13%200848B

Direct link
http://www.malossistore.co.uk/famiglia2 ... ch=131012B

From the pics,it looks that PHBE and VHSB have similar groove spacing.

VHSB



PHBE

[Adam_Winstone]

Good links, thanks

[gaz_powell]

https://www.beedspeed.com/mobile_produc ... ts_id=8193

[Adam_Winstone]

Thanks again. That's exactly what I want, the right part for the right job, and at that price you don't want to be having to modify it.

Ta