Misfiring solved ! (I hope)

[Clifford Pope]

Martin the DD is baffled too, and has given up - I'm sending the kit back for a refund.

He has tried the kit on a spare old distributor of the same serial number, and apparently it works. But with mine, the rotor arm does not point at a segment when the collar tells it to spark.
All he can suggest is that mine has been built up with parts from some other car, but fitted inside the correct Triumph body.
I don't see how that can be possible as the rotor points correctly with standard points fitted, and the car runs well.
It just seems impossible, with no known answer.

I'm going to try and concentrate on getting better parts for the standard points, or modifying them so that the springy blade stays properly located in the plastic saddle without jumping out and touching the distributor body.

Failing that, I have a good 25D distributor from a 2000. Would that fit and work? Perhaps swapping the springs to get the right advance profile?

[Alec]

Hello Cliff,

if you want to use the 25D you'll need to see if the 45D internal parts fit, the three things that determine the specification are the springs, (two different ones per distributor), the rotor which is what limits the total advance and has that figure stamped on the beak and the vacuum advance module which has the spec stamped on the side of the body. I have a feeling, but it's a while since I've seen a 45D, that the vacuum modules are different in fitting?

You really have had a dreadful time with this and trust that you get it sorted. Can not the spring which keeps coming off be fitted differently so that it stays in position? That design must have worked reliably in the past or are the replacement points just poor quality?

Alec

[Clifford Pope]

Traditional points had a loop on the end of the springy metal forming a cylinder, and this fitted over a pair of stepped insulated bushes on a threaded post. The coil wire and condensor wire had connectors which slipped over the post, and all were then secured by a nut.
Replacements, even ones sold by Chris Witor, are not positively located any more, but simply rely on the springiness of the metal to locate in a plastic shoe with a groove in it - a bit like the things railway lines sit in, only there is nothing to hold it in place. As the points open and close the spring slides a bit in the saddle.
I have found that the spring can work too close to the distributor body as it tends to ride up out of the saddle. Bending the spring so that it lies flatter in the groove risks weakening the force which keeps the contact heel pressed against the cam lobes.

[tony]

Been in hospital for the last month so have last track of this topic.
Clifford, did you reach any conclusions?
Tony.

[Clifford Pope]

No, no conclusion. The DD admitted he is baffled, but wanted me to send him the complete distributor to play with. I can't do that - I need the car for everyday. I suggested he had a play with one of his spares and then swaps it for mine when it works, but he says he hasn't got any.
I sent the Aldon kit back, but he won't refund it because I have enlarged the fixing hole, as it says to do in the instructions if there is no clearance between the collar and the module.

So I have got the (useless?) kit back again to have a go at myself sometime. Clearly what it needs is a new hole, positioned so that the module is rotated so that it triggers when the rotor arm is pointing at a segment, not half way inbetween.

Meanwhile the old points are working well, but need re-setting quite often. The occasional dither is still there momentarilly, but very rarely.

[tony]

Ironically, I've just finally finished the S, now that I'm not too sore to pick up a spanner. As already stated I have fitted Pertronix kits to all my Triumphs.
Been chasing a bad miss in the S. even pulled the front off thinking I'd got valve timing out....I haven't. Replaced badly worn carb jets as it was running very rich. That fixed the fuel problem.
Deciding that I had an ignition problem I started swapping bits off my blue 2500, same bits as the S. Rotor, coil etc swapped with no improvement. As a last ditch thing I swapped the distributor and guess what, no misses, It runs perfectly.
Obviously a sick Ignitor. I did notice an air gap on the S one that was not visible in the TC one. I may try slotting the screw hole and see if adjusting the gap will fix it.
Tony.

[Clifford Pope]

My problem is that the ignitor module bolts onto the base plate in the wrong place - about 30 degrees out, or half-way between two cam lopes.
I've given up for the moment - the ordinary points seem to be working well enough, and the misfiring is virtually gone. The gap starts to wander after a while, so needs resetting every few hundred miles.
When I get some free time I'm going to mark exactly where the module ought to be located, and then drill a new fixing hole.

[Alec]

Hello Cliff,

do you lightly grease the cam when you fit points, perhaps all the old tricks have been forgotten?

Alec

[Clifford Pope]

Yes, I do that. (But not too much)
It's not heel wear, it's simply the vagueness of the contact set up. The mounting of the rotating plate is a poor flimsy design, and it adopts a new position depending on the erratic pressure of the spring, because of the feeble plastic retaining clip.