DDK - Die Deutschen Klassiker

Have fitted the rebuilt fuel stopcock on the tank but have horrible feeling it may leak and now the tank is installed it will not be easy to reseal.
From what i could see the nut has a parrallel thread on the tank fitting and a taper thread on the stop cock. I screwed the nut on the tank until it was well up the thread. I then positioned the stopcock tight on the tank fitting and turned the nut back down until it was tight. I think the pitch of the parallel thread is less than the taper thread so as you screw it down it pulls the stopcock tight into the tank. Is this correct?
When i put some petrol in and it does leak what method should i use to seal it?

Hi Peter, I messed about with this on my old A so not sure if it will be the same.
However, I was able to take the fuel tank out with the stopcock still attached. Would it not be better to test it for leaks out of the car and then install it? I know this is extra messing about but would be worth it if it is leaking.

I have only just installed it. I am in the middle of a major Resto and getting to the stage of putting fuel in and firing it up so past that option.
I may be lucky that it won’t leak but if it does I was enquiring as to the correct procedure

A C is a little different to the earlier cars in that the stopcock is alongside the brake master cylinder under the car, so a bit more difficult to access.

The stopcock has a male LH thread, and the bottom of the tank has a male RH thread, thus turning the aluminium threaded collar while supporting the stopcock in the desired orientation is the way to go. I think that my stopcock has a fibre washer between it and the tank.

I've had it on and off several times, and the tank in and out, and it has never leaked.

Incidentally, I purchased a cheap borescope from Ebay for about £10 to look inside the tank to see if there was much corrosion. I did see a lot of petrol varnish deposit which confirmed that the car must have been sat for many years before I got it running again.
Filling the tank with a strong caustic soda mixture, and leaving it to soak for days, then following up by flushing with water, then an acid clean, then a phosphoric acid rustproofing treatment meant that my tank looks shiny and new inside for the total outlay of about £15.

The instructions I followed are here:

http://www.realclassic.co.uk/techfiles/ ... moval.html

I'm never going to bother with tank lining products again, unless there are pinholes to be sealed.

Pleased to say the fuel cook sealed up with no leaks when petrol was put in.
Its gone off for paint so nothing to do for a few weeks

Peter Roberts wrote:Pleased to say the fuel cook sealed up with no leaks when petrol was put in.

That's a relief !

I think that worrying about stuff that might not happen helps sometimes.