The Triumph Dolomite Club - Discussion Forum

Make sure you have the correct coil and measure the amps go through. Lumenition optronic or magnetronic last forever. The ones that fail, fail because the installers don't read the instructions properly or have no clue of different coils.

A lumenition needs 3Ohm primairy resistance, so a 3Ohm std unballasted coil or a 1,5Ohm ballasted coil together with a 1,5Ohm resistor. Sometimes the coil, like the Bosch ballasted ones are 1,2 Ohm you need a matching 1,8Ohm resistor.

Easy maths. 12v/3Ohm= 4 amp. 12v/1,5Ohm is 8 amp.

8 amp is for many electronic kits too much to switch so they fail very soon.

It's easy to measure with a multimeter how much amps is drawn through and then you know you have the correct parts fitted to enjoy endless of your lumenition or that it only will last 5 miles.

You can also fit a 4 amp bladefuse in the lead that connects to the coil minus to 'save' your electronic ignition kit.


An 123 ignition can switch about 12 amps and will work at almost any coil and setup and is made in NL.

Jeroen

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Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com

Yep! That's the one! I believe you need the rotor arm and push in leads that go with it too. Perhaps someone who's actually done it can confirm this!

Steve

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'73 2 door Toledo with Vauxhall Carlton 2.0 8v engine (The Carledo)
'78 Sprint Auto with Vauxhall Omega 2.2 16v engine (The Dolomega)
'72 Triumph 1500FWD in Slate Grey, Now with RWD and Carledo powertrain!

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Thanks Steve and Jeroen for you replies. I realize that I will need a 12v coil rewired directly to bypass the ballast resistor. I'll let you know how it goes.

I would recommend a ballasted type coil with a seperate matching ballast resistor. This gives a better spark during starting. Almost 90% of all car manufacturerers over the world had ballasted systems on their models in the '70s, '80s and early '90s for the obvious reason. People who don't know ignition systems advise a 12v coil.

Jeroen

_________________
Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com

Imagine the situation where you have a hot engine; a fully charged battery... and you stall at traffic lights.
If you have a ballasted ignition system the peak current when you do the restart ( as you say ) may be 12V / 1.5 ohms =8A.
But it could well be 13.5V / 1.5 ohms = 9A.
A small difference; but if the restart is not successful it may make the difference between a dead unit and one that works.

I like 12V unballasted systems with their lower currents. The current is never more than 4.5A.

Tony.

That will not harm the module for such a short period. And the theoretical 13.5 during cranking will not happen.

All lumenition manuals have in their text "if a ballast resistor is not fitted" and then the alternative connection. Not "if a ballast resistor is fitted" as almost all cars had in that time.

The ballast system is a better system.
Jeroen

_________________
Classic Kabelboom Company. For all your wiring needs. http://www.classickabelboomcompany.com

I Use Petronix Ignitor Lu-244 since 2012 on my Sprint, so many miles and no problem at all, just install and forget it!

I just took the rotor arm off the 1500, the Sprint dizzy is pretty much identical to other Lucas dizzys, so a bog standard rotor arm will fit.

As for the Leads, being Yorkshire and cheap, I removed the ends from the 1500 leads and crimped them on to the Sprint set I bought off ebay (didn't realise they were different). Combined that with a generic 12 volt coil. I did also rebuild the dizzy to make sure it was in good nick, checking the advance bob weights were free and fitted a new vacuum advance. My dizzy also has very little play, which probably helps. Plenty of clearance on the Ambassador cap.

As for overheating, you're suppose to fit the module the same way you fit a heatsink to components in a computers. There is a special grease which has to go between the module and baseplate. I am not sure what happens if you don't use it but it must come with the module for a reason.

It seems to work and considering how cheap one of those britpart modules is, I think it is worth ago.

I have the Magnetronix with the red Bosch coil, all nice and cosy under a standard cap.

No problems so far, after 8+ years.

My problem with such systems is the cost. The components cost the manufacturers buttons, the electronics inside them can be made for pennies in China. So there is a huge markup for a system which is no better than the cheapest one on the market.

Bad news about the Lucas DDB194 distributor cap ( Supposedly the Ambassador one). The terminal posts are not in the same place as the original cap. They are about 25 degrees ([s]retarded[/s]) correction advanced so it probably won't work. The rotor arm blades are in the same position (exactly opposite the locating/drive tab). If I could relocate the tab that engages with the cap it might work but I think its part of the vacuum unit bracket so that could be a non-starter in every sense! If possible it would give about 4mm of extra height under the cap. I could just have the wrong rotor arm ( DRB104C ) but I don't think its very likely that rotor arm angles were ever changed.


Post Script

It actually does run OK with this set up. I reckon that if it idles cleanly there won't be any problem as the ignition advances so it should be good. At the moment its all running at 6 volts with the Magnetronix so if I want to try the Optonics version I'll need a 12 volt coil or an external ballast resistor rather than the one wired into the loom. There are probably more pressing things to deal with first though!