That was Lucky - Now on to the Next Crisis... TR6 Ball Bearing Needle Valves Anyone?

[72BLUE]

Having spent weeks getting my Stag ready for its MOT (I had to cancel one and re-book for today), chasing a seemingly endless trail of piddly jobs that needed doing - rear brake cylinders, helicoiling rear hub studs, sorting the handbrake, broken choke cable, duff rear lights, and so on, I finally got it to the testing station today.

It behaved impeccably whilst it was there for the longest MOT that I have witnessed, (around 90 mins) it sat happily ticking over for around 20 mins, MOT man was impressed with the brake performance and general state of the car. It passed, hooray.

Then within 5 minutes of leaving the garage, on my way home, it cut out at the 2nd or 3rd junction that I had to stop at. It would only start with a floored accelerator pedal and lots of unburnt fuel was thrown out of the tailpipes.

I got it home and with the ignition on, engine not started, fuel is pouring out of the front overflow pipe down by the rad. I assume it is one or both of the needle valves.

So, I have heard that the TR6 valves that have a ball bearing are the ones to get....... anyone here bought some of these lately and can point me in the right direction?


Cheers and thanks in advance.
Keith

[stag157.7]

[QUOTE=72BLUE;236683]Having spent weeks getting my Stag ready for its MOT (I had to cancel one and re-book for today), chasing a seemingly endless trail of piddly jobs that needed doing - rear brake cylinders, helicoiling rear hub studs, sorting the handbrake, broken choke cable, duff rear lights, and so on, I finally got it to the testing station today.

It behaved impeccably whilst it was there for the longest MOT that I have witnessed, (around 90 mins) it sat happily ticking over for around 20 mins, MOT man was impressed with the brake performance and general state of the car. It passed, hooray.

Then within 5 minutes of leaving the garage, on my way home, it cut out at the 2nd or 3rd junction that I had to stop at. It would only start with a floored accelerator pedal and lots of unburnt fuel was thrown out of the tailpipes.

I got it home and with the ignition on, engine not started, fuel is pouring out of the front overflow pipe down by the rad. I assume it is one or both of the needle valves.

So, I have heard that the TR6 valves that have a ball bearing are the ones to get....... anyone here bought some of these lately and can point me in the right direction?

weren't they dripping before ? seem to remember an Italian tune up cure.

fit the viton needle valves,grosse valves have been reported as incorrect thread sizes

alan

[72BLUE]

Hi Alan, yes your memory is better than mine! There was a drip before (and water in the vee - now seemingly cured) but a good blast looked to have cured it, seems it just postponed it for a while!

Re viton v grosse needles, many thanks for the info, much appreciated! Will take your advice and have a search for the viton tipped.............

Cheers
Keith

[Staggard]

I fitted Grosse valves and as Alan said they leaked fuel around the thread. The thread has a slightly different pitch and you have to be a bit brave when tightening them up. Check them by after fitting them immerse in water with a piece of fuel pipe fitted blow down the pipe and check for bubbles, once you stop the leak past the threads (for me ) they have been perfect without any problems ever since. Graham

[StagnJag]

A trick that Bob Heritage told me was, with the engine running, pull up the fuel inertia cut off until the engine stops and then push it down again. The rush of fuel can sometimes flush out whatever debris is stopping the valve from closing properly.

(Not had to try it myself though thankfully)

Rgds

Dave

[milothedog]

This may explain things for you, from am old post of mine.

So here is what I have found out today.

1, The original type valves are 11mm -1.5mm pitch thread

2, The Grose type as supplied to me from Moss are 7/16" 18 TPI thread

3, My old Carbs appear to be threaded 11mm - 1.5 mm pitch (belived original to the car, 1973)

So the threads are different. the 11mm thread equates to 16.93 TPI if you divide 25.4 (1") by 1.5. and the angle is 60 degrees whereas the BSF thread is 18 TPI and has an angle of 55 degrees.

They are very close but if you wind one into the other you are mis-matching it, (both thread angle and TPI) I think for those that have done this, because there is such a small amount of thread on the Valve you get away with it. if it were any longer I think you run a high risk of tearing the thread out of the carb body as it got tighter.

So what can you do.

1, Find a supplier that has the correct ones (11mm threaded).

2, Run a 11mm Die down the BSF thread on the replacement Grose type valve.

3, Tap out the carb body to 7/16" BSF

4, Stick with the Original type

What will I do, I'm going with No 4 for now.

I hope this is useful and answers the question as to why some do not seem to fit. I will add this is only my opinion as to what is wrong and would like to hear any other thoughts on this.


Ian


Just as a foot note it would be interesting to find out if some carbs, TR's maybe, are threaded BSF

[72BLUE]

Thanks Ian, that is really useful info. I have also realised now that there is only one 's' in Grose!

Cheers
Keith

[72BLUE]

Came across this old thread of mine whilst searching the forum for something else, so thought it might be useful to others to update/round it off................

I decided to get the Grose valves (from TR Revington) and fitting was a doddle. They hand tighten about half way in, then need a spanner for the rest of the way. I used aluminium washers and attached a tube and 'sucked' in order to establish that they were sealed as I tightened the valves.

No problems at all for c.2months now.

Cheers
Keith