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I was told by the previous owner that my car has Dual Solex 1bb Carburetors, but I also know that carbs are often mistaken, so I didn't want to assume.  

Secondly, when I remove the air filter chamber lid, there's nothing inside (see attached photo).  Isn't there supposed to be a paper filter or the like?  Or is it supposed to be simply a few layers of the perforated sheet as pictured?  Perhaps what I think to be the feedback hose has something to do with it?

Any thoughts much appreciated!

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That's actually how the OEM air filters were back in the '50s.  You sprayed oil on the mesh and it filter the incoming air.  From SAMBA - They simply have two grids, an exterior one and an interior one, whose grid allows the passage of dust and other small objects.  The theory of how these work is that the woven wire mesh causes the air to change direction as it goes through the mesh and the dust is thrown against the "outside" surface of the bends and sticks to the oily surface of the mesh. Similar to how an oil bath filter throws the dust against the oil bath surface as the air changes direction through the filter.

The Original German Knecht air cleaners said "nach dem Reinigen einoelen" on them i.e. oil after cleaning.

According to Pelican Parts - Simply apply the cleaner onto the filter element, let it soak, and rinse. Once dry, the oil can be applied. Take care to not over-oil the filter. Refer to the instruction sheet for more information.

 

@Robert M thanks for those points.  Hmm, I'm thinking of picking up a generic air filter from the local parts store that generally fits (I'm assuming the exact spec probably doesn't matter all that much so I don't have to confirm they're Kadron and find the exact filter).  Then creating a hole on the side of the filter for the hose to enter into.  Yes, it's a kludgy solution, but I'm assuming it'd work?  

I should've originally mentioned that I smell fumes even when in the driver seat.  I was assuming that it's out the exhaust from running lean vs rich, but perhaps it's from these carbs because fumes dumped into that mesh chamber are easily escaping out?  

@WOLFGANG hmm very interesting.  I can't help but wonder if that solution performs equivalently or even better than a filter media-based solution (paper or cloth or whatever they can be).  

I guess I should mention what I just did above to @Robert M:  "I smell fumes even when in the driver seat.  I was assuming that it's out the exhaust from running lean vs rich, but perhaps it's from these carbs because fumes dumped into that mesh chamber are easily escaping out?"

I guess I don't know enough about the function of the carb, I thought it pulls in air, in which case gases wouldn't make it out and into my nose in the driver seat.  But perhaps it doesn't vacuum at all, or there are times when it doesn't.  If so, perhaps having a paper filter would contain those fumes?  Maybe I'm way off here, but seems reasonable.

@WOLFGANG posted:

That's actually how the OEM air filters were back in the '50s.  You sprayed oil on the mesh and it filter the incoming air.  From SAMBA - They simply have two grids, an exterior one and an interior one, whose grid allows the passage of dust and other small objects.  The theory of how these work is that the woven wire mesh causes the air to change direction as it goes through the mesh and the dust is thrown against the "outside" surface of the bends and sticks to the oily surface of the mesh. Similar to how an oil bath filter throws the dust against the oil bath surface as the air changes direction through the filter.

The Original German Knecht air cleaners said "nach dem Reinigen einoelen" on them i.e. oil after cleaning.

According to Pelican Parts - Simply apply the cleaner onto the filter element, let it soak, and rinse. Once dry, the oil can be applied. Take care to not over-oil the filter. Refer to the instruction sheet for more information.

 

Yep.

 

FWIW, Uni sells foam "pre-filters" that go over the outside for a little extra filtering. But that would mean fitting the lines to the top of the filter like Robert suggested. 

imageimage

I have some on my Dellortos, simply because I needed a splash of color and Chuck, the owner of Uni is a friend and my Motul dealer. 

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Last edited by dlearl476
@IaM-Ray posted:

It looks like that in your setup. Also your hose from the oil filler side does it goto the valve cover ?  Then it must be a breather as well.  Wolf’s diagram is pretty detailed description of venting

I got tired of my driver's side carb getting dirty from the oil so I eliminated the breather to carb hose. Having an electric fuel pump, I have a 1/2" line out of the block off plate and a 3/8" line from my filler both going to a breather/catch can that vents under the car. 

According to the Samba brain trust that's adequate PCV for a 2L motor, but I've noticed a few drips out my valve covers after long 80 mph blasts on the freeway. I'm ok with that. 

@dlearl476 The UNI is an interesting option.  So it's like a beer koozie but for your carb chamber haha.  But breathable and not for insulating heat of course.  

I could do one of those and cut a hole in the side so that I won't have to fit the hose in from the top.  And it would add a splash of color like you pointed out.  So this is in addition to a paper filter already on the inside of your carb chamber?

Just to be clear, I think you're specifically referring to www.unifilter.com -> Online Catalog -> Automotive Filters -> AUTOMOTIVE FOAM FILTER WRAPS FOR ROUND FILTERS ?  These are only foam that would wrap around your existing chamber (so no metal housing).

Following up for posterity- Unfortunately, now that I'm back with the car and able to take measurements, the UNI filters don't come in a size small enough for these carb air chambers.  At least the filters I was able to find.  The smallest UNI sells are 5" OD (and very tall although that's a good thing because you could cut in half and you'd have your 2 filters), meanwhile my chamber is 4" OD.

I got kind of stuck, but then realized I wasn't really thinking about which filters I'm supposed to get for this carb anyway??  I've seen: 

 Would any of these work?  Or some other product that's supposed to go with these?  I can't imagine that I have some rare exotic carb setup, there have to be some common go-tos, I just don't know better.  Some more closeups to help:

IMG_4197IMG_4195IMG_4196

 

Noting plan B here:

I visited a motorcycle store, where I came across this UNI foam air filter (NU-4132ST) that would fit inside the carb air chamber.  And also this UNI sheet of foam (BF1), which is pretty cool because you can cut to size and it ends up being cheaper when you have 2 chambers to address.  However, someone mentioned that these foam filters degrade over time.  I'm thinking maybe it's not ideal to have them on the inside vs the outside koozie method?  Maybe they end up clogging over time.

I was able to search by dimension on K&N's site and identify this K&N air filter (HA-1088) that I *think might* fit.  Although kind of expensive when you have to buy two, and I'd still have to punch a hole on the sides for the feedback hose.  But this makes me return to realizing that there are supposed to be air filters actually designed for these specific carbs...

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Last edited by Sean Seena
@Sean Seena posted:

@dlearl476 The UNI is an interesting option.  So it's like a beer koozie but for your carb chamber haha.  But breathable and not for insulating heat of course.  

I could do one of those and cut a hole in the side so that I won't have to fit the hose in from the top.  And it would add a splash of color like you pointed out.  So this is in addition to a paper filter already on the inside of your carb chamber?

Just to be clear, I think you're specifically referring to www.unifilter.com -> Online Catalog -> Automotive Filters -> AUTOMOTIVE FOAM FILTER WRAPS FOR ROUND FILTERS ?  These are only foam that would wrap around your existing chamber (so no metal housing).

Sorry, Sean, I missed this. Yes, it's in addition to the gauze (not paper) filter. Not really "inside." This type of air filter is a top & bottom plate holding a K&N-type filter (like EMPI 8802 you posted above, only oval.)

FWIW, I think a lightly oiled foam wrap on your properly oiled metal mesh filter would be just as adequate as any filter. It's just that cleaning/oiling becomes another maintenance item. 

Last edited by dlearl476

Option one above looks to be your best option. Measure across the bottom plate on your carburetor and see what the inside measurement is. Contact the parts supplier and see what the measurement on the air filter is to determine if they will fit.

Initially my Knecht air filters came with a bit of foam that fit on the inside of the wire mesh. After my second drive the foam was shedding small bits of foam and it clogged the idle jet. I threw away the foam and bought some 3 1/2" round air filters and put them inside the air cleaner where the foam had been. Haven't had a problem since.

As others have said, I'd drill a hole in the top of the filter housing and reroute the hose to the top of the housing.

Here's the thread where I installed the K&Ns: https://www.speedsterowners.co...9#590585063454865599

Last edited by Robert M

Just for completeness sake / future members that might run into this problem, I first tried the EMPI air cleaner assemblies (easily found through various vendors including here on this Kaddie Shack page I'll be referring to https://shop.kaddieshack.com/K...ng-Hardware_c184.htm).  But my engine deck lid wouldn't close.  Jeff Lain (@ Kaddie Shack) said he'd never encountered that problem before.

That meant that the Kaddie Shack "Old School" assemblies probably wouldn't fit either (they're slightly shorter).  Therefore, I had to go with the Low Profile "Old School" assemblies.  See that link above for these.

Importantly, I noticed that my gas fume smell problem still persisted.  I suspected that this was because I hadn't oiled the paper filter media.  I followed Kaddie Shack's guide tutorial (Kaddie Shack Tech TV: How To Service Dual Carb Air Cleaners https://www.youtube.com/watch?v=XDXqfZALFXA).  

In other words, spraying the filters with Johnson & Johnson baby oil and applying vaseline grease to the filter rims (tried to write this in a way to minimize the impending jokes!).  That dramatically lowered the fumes.  I still smell fumes or other things, but it's probably now the expected/accepted level of smell for these types of cars.

Deck lid not closing with dual carb air filters..... I have seen this when a VW pan was shortened (CMC - FF )  but off a few degrees on the horizontal plane which causes it to be raised up a bit in the back end.  Persistent gas odor is usually either a small weeping fitting leak, or a fuel pressure regulator set too high and gas gets by the float needle seat especially when it is first parked until the excess pressure bleeds off.  Any chance your oil has a gas smell ?

Last edited by Alan Merklin

I read an interesting post on a hose/fitting site yesterday. (XRP?) Someone put a sniffer in his engine compartment to trace a gas smell. Turns out his Earl's Performance SS gas lines were "sweating petrol." Rubber lined vs TFPE lined SS hoses.

Reminded me that my gas smell pretty much went away after I replaced my old fuel pump, filter, and all my hoses with new BMW fuel line. But I redid the filler/tank seal and stopped filling my tank to the brim at the same time.

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