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Misfiring solved ! (I hope)

Posted: Sat Mar 28, 2015 10:04 am
by Clifford Pope
A year or more ago I started a long thread on a very annoying occasional misfire, and worked through lots of possible remedies, each apparently curing the problem, but only for a while. The difficulty of course is that with an occasional sympton doing anything has an apparently beneficial effect - cars respond to the placebo effect too !

I though the misfire had finally been cured, although I never knew what had really been the cause, it just went away.
Anyway, over the past few weeks it has returned, but more so, and with the same odd feeling as if something was momentarily sticking or shorting.

Yesterday, yet again carefully re-checking the ignition gap, and also trying another condenser, I found the cause. It is the new-style points. New replacements don't use the traditional loop on the end of the spring and a pair of stepped bushes on a post, but a silly flimsy bit of plastic with a groove which seems to rely on not very much to hold it in place and also grip the condenser connection.
It was new from Chris Witor, but what I found was the spring gradually shifts along the groove, moving the long arc closer to the body of the distributor. Thus it begins to short the points, but erratically depending on the movement of the plate by the vacuum advance device.
I moved it back into its proper position, bent the spring a bit so that the curve was further away from the side, and applied a dab of Araldite. The car now runs like a dream. I could tell it was better immediately on firing up - it leapt into life and immediately ran smoothly on minimal choke as it used to.

I've found that the Distributor Doctor sells all the bits to convert a distributor back to the old tried and tested set up. The modern replacement sliding plate arrangement is awful - the plate tilts depending on the pressure exerted on the adjusting and clamping screw so altering the gap, the condensor doesn't sit properly in its recess, the braided link wire is feeble, and then this shoddy attachment of the spring.
I haven't bought the bits yet, but on his website he says he sells everything - including correct bob weight springs a fraction shorter than original to allow for the inevitable accumulated wear in the pivots.
I'm even suspicious of the red rotor arm I've got. Apparently they are now faked in China too, so just because it's red doesn't mean it's a proper one.

Anyone have a similar experience and used the Distributor Doctor?

Re: Misfiring solved ! (I hope)

Posted: Sat Mar 28, 2015 2:18 pm
by Charles H
Martin a great guy and only sells quality! I suggest you buy an Aldon Ignitor system from him! Will be one of the best buys you ever make!

Re: Misfiring solved ! (I hope)

Posted: Sat Mar 28, 2015 3:14 pm
by Lloydpiestate
hi clifford,

i had the exact same problem last year with the spring touching the dizzy body, as i quick fix at the road side i slid a piece of thin card that was in the boot, between the two, and all was fine, and as i type this, it has reminded me that it is still there :shock: and perhaps i need to do a proper fix !!! mind you, its been there for almost a year now, so perhaps i should use the rule of ' if it aint broke dont fix it ' :lol:

Re: Misfiring solved ! (I hope)

Posted: Sat Mar 28, 2015 3:45 pm
by Clifford Pope
I've been looking at the Aldon kit, and just watched an interesting clip on YouTube showing it being fitted to a Morris Oxford.

It showed them fitting what was called a new base plate, but actually that is just the adaptor for mounting the new module. It wasn't clear what happens to the old 2-part plate which rotates with the vacuum advance. Does it still use that? Presumably that plus the centrifugal advance mechanism have to be good or replaced first, or timing will still wobble about?

They made the timing look very easy - it seemed to be spot-on without needing any adjustment. Presumably the magnetic collar will fit in any of six different postions - how do you set it up so that it triggers on the correct cap segment? Or is it marked so that you can align it roughly just to get the engine running? I remember setting up Luminition years ago and you could see what stage the chopper blade was at in relation to the sensor, so knew which HT lead to connect to each plug.

I can see one obvious advantage over Luminition - no fragile chopper blades to break or catch on the wires as the plate turns.

Re: Misfiring solved ! (I hope)

Posted: Sat Mar 28, 2015 3:48 pm
by Clifford Pope
Lloydpiestate wrote: mind you, its been there for almost a year now, so perhaps i should use the rule of ' if it aint broke dont fix it ' :lol:
But won't it be wearing as the base plate turns with vacuum changes?

Re: Misfiring solved ! (I hope)

Posted: Sat Mar 28, 2015 4:56 pm
by Charles H
The plate screws down onto the original base plate and therefore the advance system still works as before, BUT crucially without the sideways force applied by the points. Therefore the system will work unimpeded and there is no points scatter even with a worn shaft. The magnets for the 'hall effect' are in about the right position, so to fit, just screw the thing down, push on the collar and rotor arm, plug the wires onto the coil, put on the cap and just start the engine. It really is that simple. It takes longer to wrap the wires in black to the coil and trim them to length to give the right look! That of course is not even really necessary. Then adjust the timing with a strobe. Last time you should need to do that. Now enjoy the easier starting and smoother performance 10 minutes work has given you. BIG smile on face!! :D

Re: Misfiring solved ! (I hope)

Posted: Sat Mar 28, 2015 7:18 pm
by TedTaylor
I have an Aldon distributor on the Team Thailand Landcrab. It was fitted to the engine in 1993 and was used on the London to Sydney Rally of that year in a different car ....... and is still going fine even when the car has been standing for a while.

It really makes me consider fitting an Aldon set up to Woodie when then present electronic system breaks down ....... as I bet it will now I have mentioned it :lol:


Re: Misfiring solved ! (I hope)

Posted: Sun Mar 29, 2015 7:03 am
by Clifford Pope
Many thanks everyone. Definitely time for an Aldon unit I think.

I've got the point (!) now I think. There must be 6 magnets in the collar, so it doesn't matter which position it fits over the lobes. Any of them can be used to trigger the spark - where the spark goes is determined by the rotor arm.

Re: Misfiring solved ! (I hope)

Posted: Sun Mar 29, 2015 9:56 am
by Charles H
Go to the top of the class, hand out the pencils and have a lollypop :D :D :D :D :D :D :D

Re: Misfiring solved ! (I hope)

Posted: Mon Mar 30, 2015 8:51 am
by Steve G
I fitted an Aldon Ignitor to my 2000 not long after I got it. I had used a Luminition kit in a Mini but that seemed far more complicated considering it did the same job.

The only problem I had with the ignitor was that the magnet holder that fits on the cam was a bit loose. I fixed this with a bit of PTFE tape but next time I tried to remove it the magnet holder came apart and all the magnets fell out.

This was back in the mid 90's so they are probably made differently now. I wasn't too worried at the time, I replaced the magnets and glued the holder back together. It was only when the car was ticking over on about 3 cylinders that I realised I might not have fitted all the magnets back the correct way round !

With a new one fitted it was fine again.