Zenith carburettor fuel rail connection?

[Judder]

I've just replaced the flexible fuel line joining the two parts of the engine bay hard fuel line, and reconnected the carburettors with two copper crush washers, one on each side of the banjo bolts

On testing the fuel system under pressure, both outer sides of the banjo belts are leaking ever so slightly (see photos) so should there only be a copper crush washer on the inside of the banjo bolt?

I have tightened the banjo bolts to reasonable hand tightness but didn't want to overtighten then for risk of stripping threads on the carburettor or similar

Any advice much appreciated and I would urge other owners to check their rubber fuel hoses on a regular basis as the joining part on my engine that was hidden behind the back of the engine was leaking like a sieve!

Many thanks

Alex

 

[Judder]

The original sized copper crush washer is on the bottom right in this photo and the new replacement ones I got are middle right and top right

I also ordered aluminium ones which are the left two but haven't used those as I think copper ones are meant to fit better

The new copper ones are ever so slightly thinner than the original ones so not sure if wider ones will help...

 

[Judder]

and this is what the original pipe looked like before I replaced it - you can see it glistening with the fuel that is leaking through it

 

[Mike Ruddy]

The 2 banjo bolt washers are different sizes, 12mm inside diameter near the bolt head, 11mm inside diameter next to the carb.They can be aluminium, fibre or copper and you can get aluminium with an O ring attached. I prefer fibre, they require less torque but check for seepage with a finger after a couple of days as the washers take on fuel and nip up as required. Don't over tighten, the pot metal threads won't stand for it. If the banjo bolt bottoms out with the two washers, add a third.

 

[Judder]

Thanks Mike - awesome feedback, many thanks

Weirdly mine are leaking on the outside but _are_ 12mm inside diameter so I would have thought it was the inside that would leak in this case as they should be 11mm according to the specs above

What I'm going to try is one of the wider aluminium ones on the outside and see if that helps - if not I can order in 11mm ones and try those too

Can you remember what the outside diameter of the ones you use / used are or where you get them from?

Thanks again Alex

 

[Mike Ruddy]

It's the inside diameter that's important. Talk to either P R Services or Roger Bray, tell them what you're doing and they'll be able to advise and supply the correct parts.

If you're working on your car like this I recommend you look in on DDk and the 356 Registry.
http://www.ddk-online.com/phpBB2/index.php
https://forum.porsche356registry.org/search.php?search_id=unreadposts&sid=052650d66759e3495d77daba88793c5a

 

[john356]

Alex
The correct washers are 616 108 423 00 and are made of fiber. Copper gaskets will work harden.
Are you a member of the 356 Registry? If no join now.....
https://porsche356registry.org/
KTF
John

 

[Judder]

Thanks both and yes re-joining the 356 registry makes a lot of sense

I've just checked the banjo bolt connections today and so far there is no more leaking than the photos above show, and the fuel system is under pressure as I have a manual primer that I use to prime the carbs, so maybe it just takes them a while to bed in properly

Either way the part number is much appreciated and I have ordered matching fibre washers in 12mm x 16mm x 1mm (which is the right size from the parts diagram) so can replace with these and pad as needed if the copper ones continue to give me a problem [s1]

Thanks again, Alex

 

[Judder]

https://www.stoddard.com/61610842300.html

Washer, 8 required, (Early 356, 356A w/Solex carburetors), 6 required, (356A w/Zenith carburetors), 4 required, (356B, 356C, 912). 12mm x 16mm Fiber Washer for banjo bolts, Fits 356/912 with Zenith and Solex carburetors 61610842300

 

[Robin]

Alex, You should change all of the old braided hoses, for multi fuel ones which resist attack by the alcohol in modern fuels.
I changed all of the flexible fuel hoses on my 1964 356C and happily use 95 octane fuel. (still 8.5:1 compression ratio)

 

[spineynorman48@hotmail.com]

Try annealing the copper washers. Heat carefully to red heat, allow to cool. This should soften them. Some people quench in water but I have found cooling in air works well.