Fuel Primer / Tank Thread

[Bensdexta]

What thread is this, BSP perhaps? Is it tapered, or perhaps just the male thread is tapered?


When my primer is pointing in the correct direction to suit the fuel pipes, it is only screwed in 1.1/2 turns? Is that enough - I will have to use some thread locker to seal it in that position?

So how do you get your primer screwed in tight & pointing in the correct direction?
TIA

[henk]

Ben,

The first one that I wanted to fit to my tank was leaking every time I put it in. I used all kinds of seals. Ordered a new one and it fitted right away. The first one had to small thread on it. (Monday product)
Maybe yours is a Friday and to big.
Be careful to tight it to much. Mine broke, leaving half of it in the tank.

[Bensdexta]

Henk,
My 'new' primer is a 2nd hand one modified a la Stefan, so it has fitted in the past.

The primer fits better, with more turns in a spare fuel tank I have, but I would like to use my original tank, so maybe its thread needs cleaning out?

Do you know what the thread in the tank is?
Thanks for the reply.

[henk]

Sorry Ben,

No idea.

[Tubal Cain]

Ben,

For pipe threads the following applies:-

Parallel threads are normally sealed with a copper or Dowty washer.

Tapered threads seal on the thread itself using compound or tape, the fitting is then screwed into the socket until it is correctly orientated. But if you can only screw it in 1 and 1/2 turns I would suggest that it is insufficient for safe operation.

I can confirm that it is a 1/2 inch BSP tapered thread.

Are you sure that the threads in the tank are clean and that the threads are compatible?

Gerald

[Bensdexta]

For pipe threads the following applies:-
Parallel threads are normally sealed with a copper or Dowty washer.
Tapered threads seal on the thread itself using compound or tape, the fitting is then screwed into the socket until it is correctly orientated. But if you can only screw it in 1 and 1/2 turns I would suggest that it is insufficient for safe operation.
I can confirm that it is a 1/2 inch BSP tapered thread.
Are you sure that the threads in the tank are clean and that the threads are compatible?

Hi Gerald,
The tap to tank thread looks bigger than 1/2". From a basic measurement it looks like 3/4" dia with 14 threads/inch.

Are both male & female threads tapered or just the male (fuel tap) thread?

I have no reason to think the threads are not compatible as both tap & tank are 2nd hand and been used before, the tank on my tractor but the tap on another.

Many thanks for your help,
Ben

[Tubal Cain]

Ben,

Pipe threads are designated by the pipe bore. So a 1/2" BSP taper male thread has a mean O.D. of 0.825" and 14 tpi.

Both male and female threads are tapered. Looking at you photo both threads look to be clean, so it may be due to machining tolerances.

I would suggest that you try to borrow a suitable tap and die to ease the threads in the tank and on the tap.

Gerald

[Bensdexta]

Pipe threads are designated by the pipe bore. So a 1/2" BSP taper male thread has a mean O.D. of 0.825" and 14 tpi.
Both male and female threads are tapered. Looking at you photo both threads look to be clean, so it may be due to machining tolerances.
I would suggest that you try to borrow a suitable tap and die to ease the threads in the tank and on the tap.

Gerald,
Did this, problem solved.
Many thanks ,
Ben