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Carburettor super torque

Posted: Wed Aug 19, 2009 11:08 pm
by rosbullterier
Just looking at all those lovely shapely carb bell mouths in previous pics -

Where are ours?

Re: Carburettor super torque

Posted: Thu Aug 20, 2009 12:39 am
by 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.

Re: Carburettor super torque

Posted: Thu Aug 20, 2009 1:18 pm
by 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

Re: Carburettor super torque

Posted: Thu Aug 20, 2009 7:44 pm
by 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

Re: Carburettor super torque

Posted: Thu Aug 20, 2009 9:49 pm
by niander
Are any gunna be brass?

Re: Carburettor super torque

Posted: Thu Aug 20, 2009 10:14 pm
by 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.

Re: Carburettor super torque

Posted: Sun Aug 30, 2009 7:29 pm
by 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

Re: Carburettor super torque

Posted: Sun Aug 30, 2009 8:51 pm
by 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.

Re: Carburettor super torque

Posted: Mon Aug 31, 2009 11:19 am
by Collector Inspector
OK!

Bruce