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Fri Aug 18, 2017 3:25 pm

OK, I have started the process of plumbing my newly reconditioned gas tank, new fuel filter (not located in the engine bay) and finally attaching the new fuel line to the new Weber IDF 40's.

Here is where I've got questions. The fittings from the fuel tap and in and out of the fuel pump are (I think) 5mm German braided lines. Everything fits like a glove until I get to the carburetors.

The inlets at the carbs looks to be 7mm. I played with a bit a of lube but the smaller lines do not want to attach to the larger inlet fittings.

Are there 5mm inlets for the Weber IDF? Do I need to keep the 7mm inlets?

This is my first go around with dual carbs and I'm a bit out of my sphere of knowledge.

Here is a photo of the dilemma.

You can see the difference between the fuel pump and the carb inlet.
How to proceed?

Thanks folks,

dgsaz

Fri Aug 18, 2017 5:05 pm

If you can get another threaded barbed fitting for the fuel pump hose 'size' put the two together with a plumbing coupling as an adapter. From 1/4" to 5/16"

Fri Aug 18, 2017 5:43 pm

I went with push-lock hose and -4 fittings. I run an electric FP up front w/ a CIS filter (also up front) and a compression to AN fitting on the metal line at frame horn. And then a "T" fitting on driver's side near carb. No hose clamps needed. cost was a little more, but very reasonable and hose and brass have dealt very well with todays fuels.

Fri Aug 18, 2017 5:52 pm

You can change whatever parts you want, but I think you should use 1/4 or 5/16 fuel hose, because this is the USA and that's what's available.

The weber barbs are most likely 8mm (same as 5/16)

Fri Aug 18, 2017 6:37 pm

After reading the comments thus far, I would like to find 1/4" fuel intakes for the carbs and plumb the entire system in 1/4".

Does anyone know of a source for 1/4" Weber fuel intake? Metric threads.

I thinks that's the way to go.

dgsaz

Fri Aug 18, 2017 6:57 pm

The threads are about the same as our oil pressure sensors, meaning probably metric but it's SO close to 1/8 pipe that you can hardly tell for sure which it is. I've seen 1/8 tapered pipe barbs or 1/8 straight pipe thread screwed into them but I don't think it's right, but it's close enough to work. Dab of red loctite to make sure it seals and won't come loose is a good idea in any case, just make sure to rinse and blow out any excess.

It's also possible to fit MOST brands of 1/4 fuel line over the 5/16 barb, and once again that's not really "correct" but put some silicone grease on there and some Gates, Goodyear, or other GOOD brand of low pressure fuel line, it'll go, it will go, and plenty tight.

Dealing with fuel I can't endorse doing anything fishy like that but IMO, that's less risky than using some unmarked fuel hose like some places are selling. With no brand and part number to read, you don't know if it's Continental or imitation, ethanol safe or not. There is "mystery hose" out there and it IS causing trouble.

Fri Aug 18, 2017 8:39 pm

Use one of the plastic fuel filters just out of the tube by transaxle. 5mm cuel line coming off metal line and i to fuel filter......7mm fuel line coming off of fuel cilter to go to carbs. Thkse filters are stepped to allow you to do this. Cheap....easy....and made to do that way.

Fri Aug 18, 2017 8:42 pm

You should be able to buy a reducer in a barbed fitting

Fri Aug 18, 2017 9:50 pm

Come out of fuel pump and use 1/4 to 5/15 barbed fitting (reducer) and do all plumbing from adapter to carbs in 5/16...

Should be available at most any hardware store or big box store...

Dale

Fri Aug 18, 2017 9:53 pm

dgsaz wrote: After reading the comments thus far, I would like to find 1/4" fuel intakes for the carbs and plumb the entire system in 1/4".

Does anyone know of a source for 1/4" Weber fuel intake? Metric threads.

I do!
Definitely NOT pipe (taper) threads!
I ordered these . . . http://www.ebay.com/itm/Metric-M10-M10X1-Male-X-6m...25cc0d6b9f

The photo in the 'Bay ad is not the actual fitting!
What they sent to me looks quite different . . . The new 1/4" barb (on the right) is plated brass . . . that's the O.E.M. Weber fitting on the left

Fri Aug 18, 2017 10:11 pm

Just use the cone shaped fuel filter it has 2 different size stems.
That will be your adaptor, I've alway used that with a dual carb set up, works just fine.

Fri Aug 18, 2017 10:29 pm

yes that's it, -10x1 thread-
Not too keen on the plastic fuel filters......but I might endorse a T fitting, a odd tee fitting with one 1/4 and two 5/16 barbs is probably easier to find than the 10x1 1/4 barb fitting, which....hey it's great that it does exist.... but you gotta admit that's a mutant bastard child of a fitting if there ever was one :shock:

Fri Aug 18, 2017 10:45 pm

modok wrote:
Not too keen on the plastic fuel filters......but I might endorse a T fitting, a odd tee fitting with one 1/4 and two 5/16 barbs

I'm with ya Glen on the plastic filters . . . especially when placed between the pump and carb(s)!
Wasn't gonna mention it because OP is lookin' for fittings to fit his carburetors, but . . . .for my Italian IDFs, one of these from the same seller . . . http://www.ebay.com/itm/Reducer-Hose-ID-5-16-to-1-...mp;vxp=mtr

Sat Aug 19, 2017 7:42 am

Possibly...

https://www.belmetric.com/barbed-hose-adapters-c-1...10768.html

Dale

Sat Aug 19, 2017 9:16 am

57BLITZ wrote: dgsaz wrote: After reading the comments thus far, I would like to find 1/4" fuel intakes for the carbs and plumb the entire system in 1/4".

Does anyone know of a source for 1/4" Weber fuel intake? Metric threads.

I do!
Definitely NOT pipe (taper) threads!
I ordered these . . . http://www.ebay.com/itm/Metric-M10-M10X1-Male-X-6m...25cc0d6b9f

The photo in the 'Bay ad is not the actual fitting!
What they sent to me looks quite different . . . The new 1/4" barb (on the right) is plated brass . . . that's the O.E.M. Weber fitting on the left

We have a winner. I bought two of these and I believe this should solve the dilemma.

Thanks all,

dgsaz

Wed Apr 12, 2023 5:29 am

I am almost finished restoring and building a big engine for a 1958 Beetle European. I need 1/4 inlet fittings too but I solved that by tapping in a piece of 1/4 inch copper tubing and soldered that. If you want a "barb" you could use a tubing flare tool and slightly "bulge" the tubing. Works for me! https://www.facebook.com/profile.php?id=100086344580438&is_tour_completed=true If you are interest in following me (I'm 80 now and spent 40 years restoring VWs and I do it all) this is my Facebook page "VW BeetleMania"[.