Misfiring solved ! (I hope)
Posted: Sat Mar 28, 2015 10:04 am
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?
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?
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 ' 
