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MG MGB Technical - Snorkel

I have a snorkel on the engine of my 78 MGB. Does anyone know what function it performs?

George
G.E. Bulwinkle

Where is it?

A photo may help.
Dave O'Neill 2

I believe you have the rare and only example of the Abingdon submarine car. Remember these were the days when there was no channel tunnel and the UK government was desperate for more accessible connections to Europe. A channel bottom, four lane motorway was proposed by a government sponsored "think tank", or "sink" tank, as the motoring press labelled it and car manufacturers were asked to submit proposed designs. The project proved a failure when the experimental car proved too attractive to migrating Minky Whales hoping to hitch a ride!
Allan Reeling

Very good Allan. Those Stinky Minkys are terrors. Come on George you've got to tell us what you mean.
Mike Howlett

Should have abandoned the idea altogether there and then. Now we are faced with having to pour millions of tons of concrete to block up the tunnels.
paulh4

Ok the device picks up heat from the exhaust manifold and feeds it into the carburetor intake. As the air intake heats up it graduately closes and allows cool air to enter the carb. I've seen similar devices on American cars of the same era. Is it put on for environmental protection? I can't figure out its purpose.

George
G.E. Bulwinkle

Ahh, that'll be one of these.

It's supposed to provide warmer air to the carb after initial starting.

My car had one fitted when SU had finished using it for development.

I believe they were fitted to the Stromberg-equipped cars.

Dave O'Neill 2

Also fitted to V8s and many other BL cars. It was an award-winning method of allowing cold start enrichment to be reduced quicker, reducing emissions and fuel consumption.

When 'cold' the intake draws air from over the exhaust manifold, which warms very rapidly after starting, feeding warm air into the carbs to aid atomisation. As the exhaust reaches normal running temperature a bi-metal flap moves to draw cooler air from elsewhere.
paulh4

Also reduces engine wear Paul, and was probably used on some models to prevent carbs icing up. Not a problem with a B, I would have thought.
Allan Reeling

Hi George,

Here is a link to Moss USA. I believe Dave O'Neill has it right, and commonly referred to here as a "heat-riser" on American cars. This was fitted to all USA MGB (export cars) after 1976 with Stromberg carb.

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29000

Regards,

Larry C.
Larry C '74 B/GT

A "heat riser" was a cast iron device fitted to the exhaust manifolds of 6 and 8 cylinder American cars in the '60s and early '70s. It had a weight and a spring that changed position as the engine warmed up, redirecting exhaust gasses through a passage inside the intake manifold. On just about all American V8 engines, of that era, there was a passage that led from one head to the other that carried these exhaust gasses when the heat riser valve was closed. When the spring warmed up, the weight would apply just enough pressure to it to open a valve that was connected to the weight on a shaft. The exhaust gasses would then flow straight through their own exhaust pipe instead of passing through the passage in the intake manifold where it warmed up the carburetor. I still have one mounted, on the right hand side of the '69 350 ci engine, in my '87 Chevy 4 wheel drive pickup truck. The hot air tube, mentioned above, routed hot air from the top of the exhaust manifold to the intake of the air cleaner. It was controlled by a bi-metalic spring and a vacuum line running to the intake manifold. RAY
rjm RAY

It's a good idea for Stromgbergs
Our Elan is on Stromgbergs and on anything colder than a cool day it will ice the carbs up about 5klm up the road from a cold startoff
It needs to be driven round town a bit to get warm before venturing out on the highway
willy
William Revit

My 77 F-100 302 V8 has that snorkel. My (sadly long since departed) Ford Festiva also had that snorkel. When the paper tube rotted away carb icing became a regular problem in even slightly damp weather. Jud
J. K. Chapin

This thread was discussed between 08/07/2016 and 10/07/2016

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