P5b with SD1 Distributor - Help !!

[markanders]

Hi

I hope someone out there can help with my 1972 P5b !

The distributor on my P5b has been changed in its past to what I believe is one from an SD1 of the electronic variety...from my research I believe that it is a Lucas OPUS 35DE8 which had a failure of the condensor (and possibly the coil) yesterday right in the middle of a contraflow, which did not go down well with the natives of Chorley !!

I have searched and searched on the web for a Condensor (there are no part numbers on the one I have) that looks like the one I have taken off but with no luck.  Does anyone know the part number (I have hopefully attached a photo !) or even better know where I could get one from ?

Thank you in advance
Mark

Attachments:

[enigmas]

Condensors are fitted to mechanical points distributors. How can your distributor be electronic if it's fitted with a condensor? The SD1 distributor drive from the oil pump tang/slot will not marry to the P5B oil pump drive unless the front cover or oil pump gears have been changed?

If the condensor is for points just adapt one from a P5B to your distributor.

[markanders]

The distributor has the following part numbers on it : 41799B 35DE8 and it uses a Lucas 54402212 distributor cap and Lucas 54424762 rotor arm....when I do a search on the net I believe it is an electronic distributor the same as used on an SD1 (and a check inside the dissy confirms no points).



Hence, if this Lucas Opus distributor 35DE8 does not have a condensor what on earth is that in the attached photo that I believed was a condensor...is it something else that I have missed and the RAC man yesterday afternoon ?!!



Mark

[enigmas]

Look here www.vintagemodelairplane.com/pages/Downloads/Rover_Tasters/Ignition05.html

I'd say it's there purely to suppress interference on your car radio!

Excerpts from the above link.
A Condenser (or Capacitor) connected across the coil/amplifier combo to suppress RF signals otherwise destined to upset in-car entertainment and offend un-neighbourly TV soap addicts. It is also alleged to assist in rapidly collapsing coil primary voltage for sharper high voltage discharge.

This may be the cause of the faulty ignition.
The Ignition Amplifier has a finite lifetime of 60-100,000 miles which can be compromised if re-fitted or replaced without proper thermal paste to allow internal heat to escape as fast as possible

[markanders]

Hahaha...now that is bizarre but funny !

It would be good except for the fact that one lead connects directly to the coil....unless the coil is actually powering the car radio as well  

[johnwp5bcoupe]

Jul 9, 2021 15:49:02 GMT markanders said:

Hahaha...now that is bizarre but funny !

It would be good except for the fact that one lead connects directly to the coil....unless the coil is actually powering the car radio as well  

Suppression

[markanders]

OMG....so seriously the "item" I thought (and the RAC gentleman) was a condenser, and is wired to the coil....is actually a radio interference suppressor ??  That is totally nuts...well its fooled us lot here !!!   

[enigmas]

Image of a car radio suppressor

Link below: Worth reading if  want an insight into the electrical/ignition system of your car. 
PS. Thumbs down to the RAC man's diagnostic skills. He's probably very young and and from the age of ECU cars?

www.howacarworks.com/accessories/identifying-and-suppressing-radio-interference

[enigmas]

Just wondering Mark...is there a problem with the distributor?

[markanders]

Yes Enigmas, she "failed to proceed" through a three way contraflow on Thursday afternoon in Chorley Town Centre...catastrophically embarrassing but five guys helped me to push it up a hill and out of the way as they were impressed with her ! I get the feeling had I been in my daily user car there would have been many horns sounded and much shouting...but no one can do that at a P5b !!

I checked fuel in the float bowls and that was fine (I've rebuilt the carbs and pump so wanted to double check !), so I asked the RAC man when he arrived to check the Coil and we both were a little unsure (that will be changed). He spotted the "condenser" on the side of the distributor and he said I should change that...hence, my futile search for a "condenser" that given everyone's help is actually nothing to do with the problem (as it appears to be a suppressor - I've never even seen or heard of one before now !).

I will now go back to my original prognosis of coil causing the problem and put the suppressor back on so that when she "fails to proceed" next time at least I can sit and listen again for 2 hours to the radio without any interference !! 🤣

[johnwp5bcoupe]

If you remember AM only days you may have appreciated the need for suppressors

[Phil Nottingham]

The radio suppressor is actually a foil capacitor which is the modern name for a condenser. The points condenser has a higher capacitance (its Ohm value)  than the radio suppresser.  FM radios may still need suppression

[markanders]

Unfortunately, (or fortunately!) I dont remember AM only, so this whole experience is a real learning curve for me !!

So if the "capicitor" or modern name "condenser" is for the radio as opposed to the points (as it is electronic ignition it should not require an ignition condenser), then there is very little chance that it would affect the poor running of the engine...

Therefore the uprated coil I have ordered should be all I require to get her back to her best...to be honest it's completely my own fault as I never changed the coil (it still has SW and CB on it so it must be before my time !!) when rebuilding her as she has the anti-theft (?) armoured cable going to her !

[Phil Nottingham]

Capacitor is the modern term but they have been used in electronics for many years and not just car ignition.  I am however quite surprised one is fitted to yours even though it is an antiquated set-up as electronic components are far less tolerant of voltage spikes and capacitors create them when discharging themselves so care needs taking in type and application

[markanders]

Very good points Phil....I will put the little fella gently back on the car and fit the new coil when it arrives.

With a bit of luck all will be well, otherwise I suspect I may need to look at installing a new electronic distributor.

[enigmas]

Mark I don't know how handy you are as a mechanic but you can do a few tests without dismantling too much. The first thing you need to do is define whether the problem is electrical or fuel related.

Electrical.
Check No.1
Simple check. Assistant required. Remove the distributor cap and have the assistant crank over the engine whilst in park. 5 seconds of cranking is more than adequate.
* Does the rotor button rotate? If yes, the distributor drive is functioning. If No, then something is broken.

Check No. 2
Remove the coil lead from the distributor cap.
Clean some metal on the cyl head or inlet manifold to bright steel or alloy.
Hold the exposed end of the high tension lead, with a pair of insulated pliers so that the terminal is approximately 3/16" or 3mm away from the steel or alloy.
Have the assistant crank over the engine for 5 - 10 secs.
* A bright spark should jump between the exposed wire and the steel or alloy of the engine.
* No spark appears, the issue is a faulty distributor, coil, or power supply.
* If a strong spark is evident, then it's most likely to be a fueling issue.

Note.
Don't throw the coil away it may be fine.
Don't just fit any coil to the module. They are all rated at different ohms and voltage outputs...even if they look similar in appearance. Don't guess check the specification.

Here's a very useful link.
www.vintagemodelairplane.com/pages/Downloads/Rover_Tasters/Ignition04.html

Note the radio suppressor in the first electrical schematic (at the base of the image) marked as RF Sup'r Condensor. RF=Radio Frequency.

Distributor
You don't need to throw the complete distributor body away because it's currently not working. The failure prone component
is usually the module attached to the side of the distributor body. This can be removed and a remote module wired to the trigger mechanism of the distributor. Chrysler and Valiant engines and Mitsubishi Sigmas of the period had remote modules that can be wired directly to the SD1 distributor. These modules can be found second hand at motor dismantlers for $20-$30 dollars or still purchased new. Second hand units generally come with a guarantee to function or are swapped for another unit. As a matter of fact I have one in my stash currently wired to an SD1 distributor. They seem to last forever as they are mounted remotely away from heat sources.

The following page on the link below shows how to wire the module to a reluctor type distributor such as yours (SD1).

Link: www.fourforty.com/techstuff/ignition.html

This is the schematic.
2 wires to the distributor, a power feed (12v) wire and a wire to the negative side of the coil.



Any half able auto electrician (but perhaps not your RAC gentleman )could wire this up.

$51 AUD. on Ebay


Link to the above unit on EBAY


Chrysler Ignition Module