Advice Please: My distributor won't distibute.

I'm trying to get my '57 Metropolitan going after 6 years of storage. Its got an Austin B series engine, and I can't get a spark at the plug leads. I can get a spark if attach a plug lead straight into the coil. If I remove the cap with leads attached and put an ohmeter to the coil end of the coil lead, and to the plug end of a plug lead, and then hold the rotor across the contacts then I get a circuit. (checked all 4 leads like this).

However, if I put the rotor and cap back on the distibutor, and then turn the engine over by hand through a couple of rotations then I don't see a reading at any point.

I can only assume that once everything's in its place then the rotor isn't making contact. (its definately rotating).

Anyone else come across these symptoms?

If it was a car I'd bought as a non-runner then I'd be wondering about all sorts of things, but I've run it for years, drove it into the garage myself (ie. it didn't break down), and it only got 60K miles on the clock (spring chicken).

So far I've replaced the HT leads, Dist cap & rotor. I've got some points and a condenser, but assume that they and the coil are fine as I can get a spark from the coil while cranking.

Any help would be greatly appreciated. Dransfield

Reply to
dransfield
Loading thread data ...

There will be no continuity when assembled and rotating as there is no electrical contact at all between the rotor tip and the contacts inside the distributor cap. The high voltage generated by the coil 'jumps' the gap to complete the circuit. The low voltage from your multimeter obviously won't jump the gap and give a continuity reading. did you replace all of the HT leads including the King lead? Is the little carbon contact in the middle of the distributor cap intact, and does it protrude and move freely on its spring?

JB

Reply to
JB

If you can get a spark from the coil, but not from a plug lead then either the spark is tracking on the cap or the rotor arm has become faulty passing the spark to the distributor shaft.

mrcheerful

Reply to
mrcheerful

Do you get a spark at the points if you flick them open and shut (with something non-conducting)? That will tell you if the low tension circuit is behaving or not. If it is, then the problem has to be with the rotor arm, distributor cap or leads.

BTW, uk.rec.cars.classic may be a more appropriate newsgroup.

Reply to
Willy Eckerslyke

( snipped-for-privacy@mail.com) gurgled happily, sounding much like they were saying :

Reply to
Adrian

try using ht leads made of wire as the coil on a car that age may not have the higher power needed by the modern leads.

the output these days are alot higher.

Reply to
aussie bongo

It happens that snipped-for-privacy@mail.com formulated :

The rotor doesn't actually make contact, it just presents a small gap across which the HT voltage can jump.

Reply to
Harry Bloomfield

what about your condenser??

Reply to
aussie bongo

mrcheerful . presented the following explanation :

I'll agree with that diagnosis!

Reply to
Harry Bloomfield

How big a spark. What sort of distance before the air no longer breaks down.

You should get any reading at all. There is a gap between the rotor arm and the pegs in the distributor cap.

It may be worth checking with the rotor arm centred in the distributor cap, that there is a fraction of a mm between the rotor arm edge and the pegs. Also at the point at which the contacts open, check position of the rotor arm wrt the cap. I assume you are rotating the engine in the right direction?

If the spark is rather limited in strength (re question above) you ought to replace the condenser.

Reply to
Fred

Carbon 'string' ones were definitely around in those days - but if original will probably have well and truly failed.

Reply to
Dave Plowman (News)

Hi Harry

Any relation to my friend Ron Bloomfield ? (V8 Pilot man) ?

mrcheerful

Reply to
mrcheerful

Thanks for all your help so far.

Thanks for pointing out that the rotor doesn't touch the contacts.....I did think it was a crap design to have those bits of brass whacking into each other hundreds of times per second.

Question about spark from coil: to be honest I did think that it was a bit feeble. It was just using a spare spark plug, so didn't 'stretch it' to see how far away from earth it will spark. I'll give that a try.

A friend reckons that the 'top hat' insulator(s) that insulate the points from its mounting post may be failing, causing a weak spark.

I've bought new condenser and points, so will fit those this afternoon and will report back. Thanks, Dransfield (Original Poster)

Reply to
dransfield

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.