worn distributor

[minor57]

have been looking at electronic ignition kits, but have been warned that my distributor may be worn, how would i check to see if it is worn? before purchasing an ignition kit, the original dizzy for my car (948 1957) is a lucas dm2 how would i identify this on the top it has lucas printed on it and it is a side exit cap?
cheers

[Bazzalucas]

I can speak only from my own experience, but the Pertronix Ignitor unit I fitted seemed to take my distributor wear in stride. Several other types make similar claims, I believe.

[bmcecosse]

If you really want to go this way - consider a complete new dizzy from simonbbc or accuspark - with electronics built in - and a new vacuum unit fitted. Most vac units are well past their sell-by date now !

[JOWETTJAVELIN]

I have never, ever had a problem with the points and condenser system in 10k miles plus and 3 years. They're easy to replace anyway should they play up. You can tell if you have a worn dizzy cap by the four terminals being worn down considerably - this should be clear to see. Personally I would never fit electronic ignition - if I wanted it I would have a modern car!

[faversham999]

I have simonbbc fully electronic 45D only about £30 works well only done 3000 with it though.

[JOWETTJAVELIN]

Also, if the entire distributor is worn, the ignition timing will have to be checked when you change it.

[RobThomas]

The long distributor shaft that dives down into the core of the engine is supported by a phosphor bronze bush (well, 90% sure it is phosy B) and it is splash lubricated via the gap between the alloy body and the steel driving end with that offset tooth, a hole drilled in the body half way up the alloy machined bit plus a dose of crankcase pressure pushing it all up the shaft towards freedom.

To test for wear, lift off the rotor arm and wiggle the shaft with your finger. Very loose will mean that the force of the points spring will be pushing the shaft one way but it might reach a certain frequency where it will take on a random wobble and this will affect the size of the points gap and the time that the points open (and hence the timing of the spark). Another test is to get a good, modern strobe light and see if the timing mark moves aroung more than, say, 2 degrees at idle. If the bush become extremely knackered then it is conceivable that the rotor arm might touch the lobes on the dissy cap and cause some damage beyond the normal wear from spark erosion. Probably quite sudde.noisy/catastrophic.

Electronic ignition has no points spring and so the shaft is not deflected to one side in the same way.

New bushes are available but the easier option is to put the old 25D4 guts into a newer body (knock out pin from bottom of shaft by the toothed steel end and refit) or to just buy a new dissy for about the same price. Since the springs go soft over the years and the timing was designed for different fuel blends then a new dissy looks like a good option.

The 22D4 dissy from the Jaguar has a shaft and bush about 1.5 inches longer and will survive better. 65DM4 from Metro/Maestro has proper ball baerings at top and bottom. Much better for long term maintaining of the timing. Drive end of dissy needs changing for the 25D4 type. Most Lucas/Bosch etc dissies will be able to be adapted.

25D4 from Midget on a sidevalve.

I expect someone will be along soon with some useful additions to this info. I'm just off to Thailand for a 24 hour layover. [frame][/frame]