53 Jubilee loses spark. Need troubleshooting help

53 Jubilee, 6V

was running well after VR tweak, when after 2 weeks of no use found battery dead. Ignition *not* left on. Battery charged, no start. Clearly no spark.

spark plug wire into top of coil -> no spark

voltage on battery side of coil, points open or shut: 6V

Voltage on distributor side of coil: 6V points open, 4.5 V points closed.

Voltage on points: 6V open, 0V closed.

if I manually open and close the points, occasional weak orange spark across the points when I open them.

When engine cranking , no sparkies seen across the points.

Swapped in known good 6V coil -> no spark

Where shall I turn next?

thanks in advance.

BIll
 
you answered your own question already.

poiints open or closed.. 6v.

means points are not making contact when closed.

when points closed.. they are grounded

check your ignition switch to make sure it is not staying on letting your battery die thru the points at shutdown.

ps.. clean and regap the points
 
@Soundguy

yeah, maybe I wasn;t clear.

batt side: 6V no matter what

dist side: 6V open, 4.5V closed

@ points: 6V open, 0V closed. Points are clearly closing and grounding

sorry if I wasn;t clear.

Bill
 
then you should have spark.

use a jump wire from bat hot to coil.. and set here and pop points manuall using a piece of wood...
 
Fizzy........you write........"dist side: 6V open, 4.5V closed"........yer points when closed are GROUND and you should read ZERO volts. Your points are BURNED and are resistive, therefore you read about 4.5-volts with the points closed. Ittza LAW, Kerchoff's Law. Do I haffta tell you to replace yer BURNED points???

Remember to POLISH the INVISIBLE corrosion from between the new points. Me? I use a clean $1-bill clamped between the closed points and pull. Iff'n yer really cheap, tear a strip from HEAVY brown paper grocery sack and use that. ........Dell, yer self-appointed sparkie-meister
 
@Dell - thank you!

That's what I was thinking.... except...

when I put the voltmeter on the 'hot' point, its 6 (open) or zero (closed) so at the points.. they are grounding and not generating a voltage across the closed points. ... so I was trying to decide how 4.5V was getting dissipated in that little length of wire from coil to points.

Kirchoff's voltage law: the sum of all potential drops around a closed circuit must sum to zero

Kirchoff's current law: the sum of all currents leaving a given node must sum to zero.

Sounder: yeah, I couldn;t figger out why I ddn;t have spark either.. "you should have spark" ... I thought so too.

What would a bad condenser act like? either a short to ground (no) or...

thanks!

Bill
 
if the condensor was shorted.. it would act like closed points.

if condensor was open.. it would let points arc and burn pretty quick.

you get some that self heal a bit then die out in a few minutes with warmth..e tc. but it's more rare.

run a hot wire to the coil.

clean points and regap.

use that known good coil.

see what you get with just the coil.. forget the dizzy cap..
 
OK, will try again. feel like I did all that - new coil, wire from coil to spark plug, regapped the points and dressed 'em wiht a card... still nada.


I am puzzled that it's 4.5V on the dizzy side of the coil and 0V on the points... how could a 6" piece of copper drop 4.5V - it can't!

So, where is the likely resistance "point" - at the dizzy feedthu?

thx!
 
chances are if it's dropping that.. it's a very bad connection somewhere else.. that's why i mentioned using a hot wire as a jumper to the coil. if it still drops 1.5v on other side of coil before dizzy.. that leaves you but one place to look.. at the feedthru.. and wy less likely.. the condensor.
 
That very same thing was happening to my 8n side mount distributor tractor. All of the electrical checks were OK.

It turned out that that terminal stud located on the exterior of the distributor where the wire is hooked from the coil was shorting to ground. When the terminal nut gets torqued, the insulation gets sheared. The insulation is made from gasket like material. I made one from plastic from the top of an aerosol can.

The tractor now starts Oh so much better with a rich spark.
 

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