I suppose its too late to try it now but it would have been good to have measured the solenoid resistance to earth (lower) and then manually operate the plunger to see if it changes to a higher resistance...
In my experience you can although it might depend on the type of electronic ignition. Its not so easy because it seems to 'fire' so the multimeter or bulb just flickers rather than staying energised/denergised like it would with points. This makes it more difficult to get it exact but is good enough to get to run and then use a strobe👍
Thats it. I believe thats the usual modification done by turning the tip down slightly so a commercially available precision ground hardened sleeve can be fitted. These will be as good as or even better than the original tip as the hardening can be more precisely controlled...
The trouble with the first option is fitting in that extra inch which I believe makes it very tight! If you had TKC899 main shaft modified to a large tip it could then be used with the single rail internals and still give a standard length gearbox....
I suppose the answer if youre going to use a bung type compression tester without help is hold it on with one hand and operate a remote starter switch with the other. These are available to buy or make one up yourself and easy to use on our cars....
If you really want to know if the washer is necessary Paul just stick something in the gearbox drive hole and measure how much goes in. Then compare how long that is with how much sticks out of your new angle drive - if what went in is shorter than what has to go in then you need a washer or you will load the angle drive as you do up its coupler. Otherwise you can just use a washer anyway as it wont do any harm🙂
As you probably know the mainshafts are longer for single than 3 rail boxes on both OD (+1") and non OD versions (+3"). What was usually done was to have a special 3 rail length main shaft adapted with a big tip to suit the single rail input...
Peter dont think exact measurement is too critical and certainly Dolomite 1850 single rail input shafts have definitely been used with 3 rail bell housings in past gearbox upgrades on here...
Re-reading your earlier post Im not sure that the early type gauge swinging around a lot on lower tank levels isnt normal. Moving iron systems because they react quicker will inherently be less stable so will move much more with sloshing fuel... Before you start spending money we need a comparison with an owner of a similar car?
You might be in luck as this comes from a very good article on Smiths gauges from triumphclub.co.nz indicating the number that should be on your sender. Then as it happens theres one of them asking for offers here on ebay: Triumph Herald & Vitesse (Some) Fuel Gauge Sender | eBay
As Pete says watch your gauges (fuel and/or temperature), if on powering up their needle rises slowly its a stabilised thermo system if on the other hand it shoots up immediately and vibrates a bit youve got the earlier type without stabilser...
Never used one Dave but Im sure theyre fine its just that with a screw type I can take readings on my own (provided Ive got the right adaptor of course)...
Yes I went the same way as Paul but bought a sheet of viton rubber on ebay as I thought it might resist fuel better. Since used it for fuel gauge sender and even front wheel arch to bulkhead flap seals👍
The porosity could be in the pressure area so fluid only comes out during use? Also you could try running with a lower level in the reservoir to see if that stops it if from the cap. In fact is the cap sealing properly as its got to prevent the slop of fluid under driving conditions...