Carburettor super torque

[rosbullterier]

Just looking at all those lovely shapely carb bell mouths in previous pics -

Where are ours?

[Charles uk]

John is expecting a delivery in the next 2 or 3 weeks when the chrome platers have finished.

These are for the Amal twin jet carb.

[Collector Inspector]

How does one get "Torque" from a velocity tube then?

Velocity tubes or bell mouths usually only work at higher RPM from my experience.

Engine "Torque Thru Induction" has always been achieved by increasing intake manifold vacuum which on a Gull, manifold volume is kinda minimal anyway due to the varied carb setups. I think that BS actually did the required restriction all thru the range actually and just let WOT take its course?

Comments?

B

[Horsley-Anarak]

RBT I will bring a few spare ones to Lerryn. ( when I find out when it is on !!!)

If this year you buy me a pint I will give you a trumpet for your SD.

H-A

[niander]

Are any gunna be brass?

[Charles uk]

Plain brass carb trumpets were only used on the naval type SD,s, i.e. the ones with the copper flywheel covers, bronze topped float chambers, brass throttle slide bodies, bronze clutch levers & unplated brass exhaust tubes.

All the rest seemed to have had chromed trumpets.

The brass trumpets have proved to be very fragile, hence thew very small number that have survived.

Naval type SD's seemed to be less than 10% of the total production based on the numbers that have survived.

At this point in time we have been unable to source a supplier of 7/8" 18 gauge brass tube other than old tiller arms, or bringing some in from the US.
Unless someone out there has a bright idea.

[PeterW]

Any reason you can't use 7/8th 16 guage..?? Its readily available in the UK as the model engineers use it

Cheers

Pete

[Charles uk]

The primary reason we use 18 gauge, is that's what Seagull used.

& here are the secondary one's.

16 gauge just gives you more work, it's more difficult to form the trumpet wether by spinning or pressing.
To tap the thread the id of the tube has to be opened up by about a millimetre prior to the thread being tapped, so it fits on the carb.
& last but not least, 16 gauge is more expensive.

The motto of Seagull part remanufacturing is,

If your copying something & not redesigning to increase functionality or durability, make it as close to identical as possible.

[Collector Inspector]

OK!

Bruce