The Triumph Dolomite Club - Discussion Forum

Hi Chaps, been competing in the GRRC Members' Sprint at Goodwood today. Was going great guns managing to beat my PB in the early sessions but not so good in the afternoon as I the car developed a debilitating misfire meaning it wouldn't really pull in higher revs third, going in to 4th, like it was running on three cylinders.

It's on new points and condenser now, but I've had this before when it was on an accuspark electronic ignition so I don't think it's that. This time it was noted that upon pulling in, the coil was very hot to the touch.

So, I'm going to replace as much as I can by putting a new dizzy cap on (got a nos ambassador cap) and want to put a Lumenition optical kit in which includes a matched coil.

I believe you buy the control unit and coil etc. but then need to buy a separate optical fitting kit?

I'd appreciate some guidance on which parts to buy please, particular for a 44d4 dizzy.

Cheers fellas!

I had a couple of failures of the Lumenition optical switch in my Sprint engine. First was an old scruffy one that was already fitted when I bought the engine but went faulty with a very bad misfire that got worse until it stranded us on a classic run. It restarted fine when it cooled down, then failed again after a few miles. I carried a spare new amplifier unit and coil which got swapped (individually and together) to prove the fault was the optical switch. Recovery job to get the car home.
I fitted another new switch but that failed totally in Machynlleth with no warning after a few hundred miles. Another recovery job.

Think you mght find getting parts to fit the 44D dizzy might be difficult.

The car is now on Pertonix and working just fine - so far!

Lumenitions can't handle too much current. Make sure the primairy restance is ok and these last for ages.

Jeroen

soe8m wrote: ↑Tue Apr 19, 2022 5:30 pm Lumenitions can't handle too much current. Make sure the primairy restance is ok and these last for ages.
Jeroen

Hi Jeroen, it doesn't look like the Lumination kit is available any more any way, so I'm attempting to get a Piranha or pertronix system suitable for a 44d4 dizzy.

Out of interest, my wiring harness has a long piece of wire as the ballast resistor, some kits insist you fit the ceramic block resistor....how is that fitted with the long wire resistor?
Is the long wire removed or is the resistor block fastened on the end of it? How does this relate to the coil? Do some coils have a ballast resistor built in or should I always fit an external ceramic one?

As far as my misfire goes it has been suggested that the accuspark coil, as it was very hot to touch has fried my condenser and points and that could be the issue? Only a theory though....

The normal Lumenition D45 fitting kit does fit. The only thing that has to be modified is some have the rotorarm too high as it now sits on the extra 1mm Lumenition chopper. Some are lucky to have a rotorarm/cap combi that just works and some have to sand a bit off the underside of the rotorarm to have it 1mm lower again. Nothing special.

The coil/resistor thing is that there are no coils with internal resistors. The windings of a ballasted and unballasted coil are just different and have their own resistance.
The primairy resistance must be around 3,0 - 3,5 Ohm on conventional ignition systems or the basic electronic points replacements like the Lumenition or the Accusparks and the Pertronixes etc. etc.

The resistance of a sparking coil while running is not a solid resistance as it’s a coil with pulsating voltage but you can use the static resistance to make your calculations.

The std resistance of the ballasted wire in the loom is around 1,6 Ohm. That needs a coil with at leat 1,4 Ohm to have 3,0 in total. Most Lucas ballasted coils are 1,5 – 1,7 and that’s fine. The best coil there is at the moment, a Bosch, has the ballasted version 1,2 Ohm. Most German cars have a seperate resistor of 1,8 Ohm to make 3. A ballasted Bosch on a Dolomite with the resistance wire has a total of 2,8 Ohm. Fine on points, no worries but read the instructions on your electronic ignition.

On the Lumenition box it say’s with large text that the total primairy resistance must not be lower than 3 Ohm. People who blaim a faulty Lumenition having 3 faillures behind eachother didn’t read or know what coil they have. Just a coil is not good enough, measure. Measure your testleads also of your multimeter. Most testleads have 0,3 Ohm of themselfves what is normal when you hold these together. Reading a coil of 1,7 Ohm is actually a 1,4 Ohm then….

As the resistance wire does vary slightly in resistance is a new seperate restisor with a measurable known restistance together with the correct coil somewhat more controllable. You know exact what you have and then you know or it will work with your electronic ignition.

Some are not that frightened of extra current. An 123ignition can switch at least a 1 Ohm primairy circuit. So only a 1,2 Ohm ballasted coil without it’s resistor even doesn’t destroy an 123 and gives a mega spark. Most ballasted coils can’t handle the current without their matching resistor but for example the red ballasetd Bosch coil can. An 123ignition with only a red Bosch coil gives the best spark without any trouble. Fitted over 250 of these combi’s over the years and none faulty.

But how is the resistance related to frying ignitions or coils?

Easy. 12v/3 Ohm = 4 amps current. Too low resistance for example 12v/2 Ohm = 6 amps current. The lower the resistance, the larger the current through the contact points or your fragile electronic unit that is designed for switching a maximum amps mentioned in the installation manual.

Using a ballasted type coil with resistor has also 4 amps through the coil. Using such a coil without or too low resistor the amps through the coil also rise and can be too high for the coil itself. The Bosch can handle easily as mentioned before as it’s a well build coil but a Lucas or one of the modern Chinese coils get hot for 5 minutes by the too large current and can be binned then.

Conclusion: read the manual and you know what resistance you need. Find your coil, measure and know what seperate resistor to use to have it as your ignition likes it.

Don’t fall for the special, super spark, high power, flashy coils because these don’t exist. When your ignition of choice can handle a low resistance coil, then you can fit a low resistance coil, mostly named sports coil or similar. The only difference is that the coils which are designed for higher amps don’t fail by the higher current. Or just fit a std Bosch without flashing images on it.

So when using a seperate resistor you don not use the resistor wire anymore. You put a 12v feed from the ignitionswitch side to the resistor and then to the ballasted coil. When using a coil with too much resistance, like an unballasted coil with a seperate resistor or resistor wire, nothing happens other than the spark at the plugs gets weaker.

There are a type of non understanding people that shout on forums and Facebook, bin the ballasted system and use normal coils. A ballasted system is THE normal system as 99% of every German, British, USA and Japanese carmanufacturers had these ballasted systems on their cars from the 70's till mid 90's when ignition types and multicoils did change the ignition systems where the singe coil/dizzycap did dissappear. The ballaste setup is far better than the non ballasted system and that's why every manufacturer did the effort of fitting such a slightly more expensive system on all their cars.

Hope all is clear but if not please comment.

Jeroen

soe8m wrote: ↑Tue Apr 19, 2022 8:33 pm The normal Lumenition D45 fitting kit does fit.....
Hope all is clear but if not please comment.
Jeroen

There's a lot to go through there Jeroen, and I'll need to go through a few times to digest it!

I'll need to learn how to use my multimeter properly now!

Many thanks for taking the time to post this, it is very much appreciated!

Cheers!

I've been running Lumenition Optronic on and off since their launch in the mid 70s and never had a failure (though I carried a spare amp box for years (still have it!)

I've always used (as instructed) a remote ballast and standard ballasted coil, bypassing a loom fitted ballast lead if need be. I never trusted these completely, even though i've never had one fail on me, which is not something I can say for remote ballast resistors, just paranoia I guess, it used to be common for petrol Transits (which mounted the resistor low on the radiator panel) to fail. Some other makes also suffer this way, it's usually down to an exposed location, like the Transit, than any particular fault with the part itself.

The symptoms are easy to diagnose, the vehicle will start and run only as long as the key is held in the start position, which effectively bypasses the resistor, release the key and it stops! It's a unique configuration that points only to ballast resistor failure.

I have a couple of known good remote ballast resistors, if you want one, i'll send it to you for postage cost. The one I just removed from my 1500FWD was actually running perfectly with a Lumenition Optronic when I bought the car. The Optronic, sold originally for a 25D4 dizzy, has found a new home (with only a different 45D4 "chopper") on a customer Sprint, running a red 45D Rotor and Ambassador cap. You just have to know what fits what!

Steve

PS, one other point to mention is that a lot of people seem to be adopting the "high torque" starter motor, most of these have the ballast bypass tag on the solenoid conspicuous by it's absence. Which kinda negates the main purpose of the ballast resistor (a calculated overload for better cold starting) In these cases, I run a standard 12v 3ohm coil without ballast. Works for me!

I have a couple of used (and untested) Lumenition control units amongst Ted's residual stuff if anyone wants to experiment cheaply...he had a habit of collecting such things from scrapyard visits!

xvivalve wrote: ↑Wed Apr 20, 2022 1:07 pm I have a couple of used (and untested) Lumenition control units amongst Ted's residual stuff if anyone wants to experiment cheaply...he had a habit of collecting such things from scrapyard visits!

Well.......relatively cheaply! A quick canvas of ebay will show that individual (new) parts of Optronic systems can be had! Control units, which are largely (if not completely) interchangeable, are around £75, the dizzy mounted optical sender, which IS vehicle specific, a 45D4 one is good for a Sprint, are around £95 and the plastic "chopper" that fits under the rotor (again a 45D4 one is acceptable for the Sprint's 44D4) is around £22.

While you sometimes CAN get away with the stock rotor and cap on a Sprint, it's an AWFULLY tight fit, best to budget for the Ambassador cap and 45D4 rotor as well. Don't forget you'll need the push fit leads to match the cap!

Still,If you can get a cheap control unit, it works out cheaper than buying an entire kit that is close to £200 these days! And you'd still need to buy the cap, rotor and leads!

Steve

...one of them has the optical sender too...

Carledo wrote: ↑Wed Apr 20, 2022 1:31 pm While you sometimes CAN get away with the stock rotor and cap on a Sprint, it's an AWFULLY tight fit, best to budget for the Ambassador cap and 45D4 rotor as well. Don't forget you'll need the push fit leads to match the cap!
Steve

The 25D rotor arm fits under the 44D4 cap, even with the blocky 45D sender units from SimonBBC. So far, I've only tested that the 25D arm works with points, which it does.

Graham

soe8m wrote: ↑Tue Apr 19, 2022 5:30 pm Lumenitions can't handle too much current. Make sure the primairy restance is ok and these last for ages.

Jeroen

I was running a full 12 volt system with a new direct 12 ignition live feed and Remax coil which is 3.45 ohms.

Call me whining but look closely to the coils and for example the rotorarm. Remax and Lucas, both the current reproductions.

No other manufacturer would invest in designing and manufacturing these old types of ignition coils for some classic cars anymore when these are widely available for 1 gbp in the far east or Asia and they only need to stick a decal on them with their own brand.

It’s all the same… Sometimes even the shapes do differ and are not even consistent. Two the same Lucas coils with the same specs and partnumbers totally different coils. What is available cheap is bought and labeled and when the next month another one is cheaper those are labeled. Three different types of Lucas sport coils. Just three times a gold coloured thing.

Please learn these you cannot call coils and have nothing to do with any quality.

In the older workshop manuals the coil resistance was mentioned sometimes at different temps. Jaguar had these mentioned I believe.
I never had such a remax in my hands as I don’t wan’t this kind of parts near my shop but maybe as you have one measure the resistance just after 5 seconds of current going through or as long as needed to have the coil temp feel by hand is at normal operating temp. Maybe the resistance is way below 3 Ohm then at normal operating temp. If you want to test, do it with long cables and seperate battery and have the coil outside as cheap (or old) coils can explode.. Not heating it up and measuring this way fitted in the car.

You must see these kind of parts as the aliexpress smartphone charge cables. It looks like one, sold as one but after one time using it there’s a breach in the cable or it doesn’t function at all when new.

That is the quality of those parts. It’s my every day struggle finding electric faults by new switches falling apart fitted by customers who are convinced they bought orginal because it was in a Lucas box.. Or sold by specialist XXX as that one defenately woudn’t sell inferior parts…

Ebay is your friend to find NOS parts. Even a 50 year old used Lucas coil is better than these.

Jeroen

Hi Shaun, you may find H&H ignition solutions,Brierley Hill West Midlands worth checking out. very pleasant to deal with and not easy to find!
I have limited experience of their unit but very compact. 01384261500 Bob

10yearsafter wrote: ↑Fri Apr 22, 2022 11:38 am Hi Shaun, you may find H&H ignition solutions,Brierley Hill West Midlands worth checking out. very pleasant to deal with and not easy to find!
I have limited experience of their unit but very compact. 01384261500 Bob

Nice one thanks Bob!