504 Hard to Start

This might be a long shot , try a positive wire direct feed from battery to coil, and replace wire from coil to to dissy ,
some of these connections have been found to be dodgy intermittently as our cars age

good luck
 
Spark Plug Test Bed

IMG_2507.JPGIMG_2508.JPG

I made up a plywood board with the plugs connected to the distributor via the HT leads.

No leaks i.e. sparks jumping. All 4 plugs sparked, but using the device shown, the spark from the lead from the coil was very vigorous and white in colour.

That contrasted with that from the plug leads which was orange. The spark at the plugs was also orange and, curiously, the spark at the plug often did not take the shortest route across the electrodes. It sporadically went around the central terminal & to the base. TBH I've seen much healthier sparks at the plugs.

I connected the spark tester to the output end of the carbon brush & got the same strong result as for the coil. The rotor checked out for continuity. If I had another pair of hands, I would hold the rotor against the brush & measure that spark.

So, tomorrow I'll try new plugs and new leads
 
The thing is that when installed in the engine, the springs are in close proximity to the metal spark plugs tubes and, so, have a tendency to arc across. Testing outside of the head probably will not be that useful. To confirm this is the problem, try swapping over the old distributor if you have it handy.

The later 504 motors had a solid connector rather than a spring and may well not arc as easily.
 
Plus 1 for the later solid spark plug connectors. Also the condenser - I have had new ones fail .
 
alpine said:
This might be a long shot , try a positive wire direct feed from battery to coil, and replace wire from coil to to dissy ,
some of these connections have been found to be dodgy intermittently as our cars age

good luck
Click to expand...
I fitted a relay from the dissy to a direct wire from battery pos to coil pos and it solved all starting problems on my 504 cab .I left the original wires connected That was 10 years ago and no problems
 
Julian Wins the Cigar

julian c b said:
I fitted a relay from the dissy to a direct wire from battery pos to coil pos and it solved all starting problems on my 504 cab .I left the original wires connected That was 10 years ago and no problems
Click to expand...

I confess I was sceptical.

But I had a new relay in my electrical drawer that I ended up not using and I was getting to the clutching at straws stage.

I hooked up to the battery via a 10A inline fuse.

When I tested for sparks at the plugs as above, the difference was quite noticeable. I saw nice fat sparks right where they should be.

It's not the 1st time I've done this. In the 90's my every day driver was a 1958 MG ZB Magnette. It used to sporadically just mysteriously cut out. When I checked there was no power to the LT input on the coil. A relay fixed it completely.

So why did it happen? I'm going to surmise that the 123 draws more power than the original unit & the old switch & wiring wasn't up to it.
 
Glad you've sorted it out. There is a lesson there for all of us!
 
The Final Chapter

Seeing that it started OK, I got a temp VicRoads permit online & hit the road.

I soon got the classic signs of an electrical misfire: spluttering under load e.g. slight incline, top gear, full throttle.

Research & consultation with suppliers suggested that the standard points coil (Bosch GT40 in my case) are not compatible with a 123 Distributor

I obtained & fitted a Beru ZS563 coil.

Hallelujah! It drove like a new car. But there's a twist.

I get home & turn the key to off. The idiot lights go out but the motor keeps running. The bloody relay has failed in the on position. Another reason to avoid generic electrical stuff like the plague. I had to redo most of the re-wiring on this car because the cheap spade terminals I got online fell off when it got a bit windy

I removed it & it starts just fine indicating the problem all along was the coil.

So, if you're going the 123 route, fit high quality leads & a suitable coil. And always buy branded electrical stuff.

Here endeth the lesson.
 
A good lesson for me as I am going to fit the 123 route
Great to hear you have it going.
 
Relays...
An anecdote about a relay. Involves a Non-Frog car, hope you don't mind.
1. My partner had a Lada Niva, a 91 model, one of the ones that went to Peter Brock's company on arrival in Australia, it got lots of parts fitted pre-delivery that were better quality than the Russian originals.
Our car was serviced by a Russian-born mechanic, a lovely bloke who insisted they were great cars, misunderstood by Australian owners and mechanics.
The starter motor started playing up, regularly it would click-click-click, not turning over. You could just keep flicking the key to start, eventually it would turn and start. Sometimes it would take many, many tries...
The mechanic removed the starter motor and rebuilt it completely. It is a cow of a job, Nivas have the engine mounted off centre a whisker, leaving more room on the left for the steering box on LHD cars but if you move the steering box over for RHD cars, access to steering box, alternator and starter motor are shocking. The rebuilt starter was fitted but the problem continued.
We asked the mechanic to just fit a whole new starter, but Lada Australia didn't supply whole starters, just parts to rebuild.
So the whole process was repeated at no cost to us.
Still it would click-click-click on occasion.
I suspected perhaps a dodgy ignition switch or a bad inline joiner along the wire from ignition switch to starter, so I followed the wire from the ignition switch... there was a clearly non-original wire running from the ign switch - I followed it over the steering column and to up behind the centre of the dashboard, I had to remove trim to find where it went - there was a Bosch relay, a quality metal case item clearly marked Made in Australia. It must have been fitted as part of the pre-delivery, I'm guessing the ignition switch wasn't up to the load of the starter solenoid so the Aussies specified a relay to improve reliability... The output of the relay went back to near the ignition switch, connecting to the original wire that would have gone direct to the ign switch before it was "Australianised." I fitted a new relay for about $10 and had no further starter motor trouble.
(But being a Niva, plenty else went wrong...)
 
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