individual Weber screens

[John Fitzpatrick]

Several posters on this forum have expressed frustration at finding suitable screens for their Webers. A hemispherical mesh brazed to a ring as pictured is something I think I can have fabricated. It would be held to the rim of the stack by a grooved rubber ring, or perhaps bendable tabs. Before going any further, is this something worth pursuing? I don't mean commercially-just enough demand to justify having a die made up.
Apologies for the poor quality of the drawing- I've just started trying out AutoCAD.

[Jim Pearson]

Hi John,

Please add my name to your list of potential customers.

Forum member "Doc Watson" was pursuing a similar idea over here in the UK - see his thread GT40 Engine Build Mirage Chassis - but I'm not aware that he's yet reached a conclusion. Might be worth your while touching base with him to ensure you're not duplicating effort.

Regards,

Jim

[Andy Besic]

Add me to your list as well.

[Larry]

Me too.

[andy loveday]

Hi John

I would also be interested in a set. Andy

[Dutton]

John,

Count me in for a set. Kindly advise if a contribution would help on the front end of the project.

Best,

T.

[TonyM]

Hi John,

I'd like a set.

Thanks,

Tony M.

[Bill Musarra]

My question. what sizes will they be made in. Is it going to be one size or will there be several. The TWMs like I have 50 mm. will need a variant I am afraid. Let us know some of the details of the project. If they will work for my setup, I am definitely in on this. Post some details if you have any.

Bill

[David Morton]

Yes please,
Dave M

[Doc Watson]

John,

I have details of possible mesh material on my build thread, I havent got much further yet as I've been sorting the short block and hunting down a dizzy. I got the inspration from seeing this photo...gotta love the dfv..... as always we are reinventing the wheel... will watch with interest.

Andy

[John Fitzpatrick]

So far what I found is that a simple screen is good for keeping out leaves and dropped coins but not so much for finer particles. The problem is that once a particle is blocked, it totally obstructs the mesh that blocked it. To filter medium-fine sand, say 1000 microns (0.040 in), we’d need about an 18 mesh screen with a 0.017 dia wire, and that configuration has an open area of 48% Without going through the calculations, it would only take about 1½ cc of sand to obstruct enough of the screen to begin restricting flow.

What this all comes down to is that it looks like if you really want to filter what goes through your Webers, we need to figure out a way to get a dome of foam under the wire hemisphere and keep it there. If coins and such are all you’re worried about, then I think a fairly inexpensive solution is possible, and I’m checking into some industrial filters that may work with just a little modification.

If anyone wants to go through the calculations themselves, some helpful information is listed below. Let me know if you’ve got an idea on the foam dome.
John


Woven wire mesh info http://www.ron-vik.com/plaintwilled.aspx

surface area of a hemisphere = π/2 • d²
1” = 25,400 microns
sand = 100-10,000 microns
hair 500 microns
1000 microns = 0.040”
18 mesh = about 50% -70% open area, approx. 1000 micron opening
60 mm trumpet, the area for a hemisphere sitting on top is 5,656 sq mm.
38 mm choke cross section area = 1,134 sq mm

[Darren]

Just thought I'd shed some light on a very simple solution to this. On our T70 race cars we use good old Tea strainers. Just cut off the handle, split a length of washer jet hose, slip around the rim and lock wire to the top of Ram-pipe or trumpet.Just the way they've been done for years. And we've not lost an engine through dirt ingress from them. And still topped 175mph at Monza C.E.R round week before last....

Darren.
CRC Racecar Engineering

[Doc Watson]

Darren,

I've lingered by the tea strainers in a local supermarket.... I assume you drilled through the trumpets to feed the wire through.... I'm trying to avoid that... also the tea strainers I've seen have (relativley) large openings between the individual wires... but neat solution.... and cool engine.

Although isnt the engine facing backwards? why else would the dizzy be at the back ;-)

Andy

[Peter Jankovskis]

I would like a set for my Daytona Cobra Coupe.

[Simon]

Here's my tea infusers--found some that have a really fine mesh.

[Jim Pearson]

Hi Simon,

Any chance of posting a close-up shot of an individual trumpet & screen?

How are they fixed to the trumpets?

Regards,

Jim

[Darren]

Originally Posted by Doc Watson

Darren,

Although isnt the engine facing backwards? why else would the dizzy be at the back ;-)

Andy

Ah, if only the '40 had been built by GM. Then you too could have your dizzy at the back.
But then if Ford had let Mr Broadley do what he'd intended everyone would be craving a T70 replica.......

I know what you mean about the wire size of various strainers. We do exhaustive testing involving many cups to decide on the correct grade of strainer. I think we settled on "House of Fraiser" 4" in the end.
Darren

[Simon]

I used 3M #2080 metal sealer to glue them to the rim, looks like weather strip adhesive but is grey in color. They have been on there almost a year and no sign of them coming loose.

Simon

[Doc Watson]

After following Darrens lead a man was reported to be seen in various shops in Plymouth this afternoon asking to look at tea strainers, showing bemused shop assistants a Weber stack saying 'it has to fit this....' ;-)

Anyway came home with 8 strainers each one cost £0.79p each!!!! They fit exactly on the Weber stack, the mesh apature is about 0.4mm and I'm just about to cut off the handles with a dremel and see if the original rubber filter holder will hold the tea strainer in place.....if not I've got some piano wire to wire them in position..... be back in an hour..... where is that dremel.....

Andy