Lotus elite 503 ignition help

[Robbie]

1979 elite 503 . Rebuilding ignition non lumination. Ballasted coil .

to negative side of coil wires to revcounter and distributor. To positive side of coil wire from solenoid and from ignition. 

The question relates to the sleeved wire from ignition to the coil. This should be a resisted wire and for a ballast system I assume carry less than 12 v. All tests, connected to coil or loose indicate full 12v. I cannot believe it would reduce voltage when engine runs as it is only a wire.

Anyone with standard ignition on an elite, does the sleeved wire from ignition itself show a voltage drop or does it have to be tested in a special way, 

Thanks Rob.

[Robbie]

May have found an answer online that if I earth the negative Side of coil in a ballasted system with ignition key on voltage should drop to say 7 v. On the positive side Or if the  points closed.  Will try a test tomorrow. Anyone like to confirm before I break something.

[Dunc]

Hi Robbie,

Welcome to the forum!

The ignition feed through the high resistance wire should be giving less than 12v across your multimeter with the ignition on.

The coil should receive its full 12v from the jumper wire running from the starter solenoid to the coil when your cranking the engine. Releasing the key back to the ignition point should return the coils feed to sub 12v.

If you are worried that the feed voltage is too high and your balasted spec coil is getting really hot with a measured 12v from the ignition switch, you can always buy a ballast resistor from somewhere like powerspark for a few quid and put it in the +12v feed from the ignition.

best wishes

Dunc

[Robbie]

Yes its strange the pink sheaved wire is thick copper and over length and coiled up and attaches to the coil and is obviously a resistance wire but gives 12v. Why its not working could be that the measured voltage only drops when in circuit ie current flowing ,which would be when the points close ,that I still have to check. Your backup suggestion of using a ballast resistor makes sense with new wiring from the ignition and I will take that option if I cannot prove resistor wire works. Car not yet started as weak spark to the plugs. New points and condenser cap and ballasted coil from SJ . Unfortunately coil from them rattles and appears in need of replacement. Think I could be in for some electrical starting problems so renewing all at the outset then figures crossed before coming to forum. 

One issue to renew points its easier to remove distributor and in most cars this is not a problem,. I note on forums some tales of horror that this is not straightforward. I intend just lifting out distributor taping end so it cannot rotate fixing points and condenser in position and returning to engine. with car not moving in same position. Anything to be careful of. 

Also number one cylinder on most cars is nearest the radiator. Is this the same on the lotus 907 engine.

 

I have a workshop manual but this is not covered thanks rob.

[oilmagnet477]

Robbie - check out @mikeeech' s project thread - in his recent video of the engine starting, he refers to cylinder 3 as the one next to the one next to the bulkhead (!) so your assessment would be correct. I would advise, if someone hasn't already, to put cylinder 1 at TDC before removal of the dizzy - assuming you mark the HT leads before dis-assembly and note where the rotor arm is, you shouldn't go far wrong. Are you sure you have the right dizzy for the spec of car? There are several set ups (search around on here or refer to manual if you have one) as things changed over the development cycle of the car. Generally, IIRC the 24D dizzy and spec 5 go together but as I say best to check. Good luck

[directordanw]

I remember being completely foxed by this on my Eclat 2.2; that did have a Lumenition but had the same shielded pink/white wire.  I finally figured it out from the diagram - it's represented by the zigzag line marked KW that runs to the positive side of the coil with the ballast resistor.  I would think that the wiring on the 503 S1 would be sufficiently similar, just bypassing the ignition amplifier from the negative to distributor.

 

[Robbie]

Great diagram. ~ I can see how a lumination would easily connect to my s1 if the distributor/optical I obtained was the correct model for S1and assume some lotus owners have upgraded . I wonder whether on an S2 with lumination lotus continued with a rev limiting  rotor  as in the S1 or the luminition module limited revs. ~Not planning on moving to lumination as yet, prefer to get my system sparking.

Not sure you know what C2 is. its  going to earth, assume it may be an interference module,, I have not got one but cannot believe it would make the resistor wire reduce voltage to 7 volts. However   it may complete a circuit which would reduce voltage across the resistor wire in which case I would need one. Any ideas.

[directordanw]

I had always thought C2 was the ballast resistor.  But it's a long time since I studied electrical symbols at O level physics..!

[Dunc]

The lumenition was fitted to the later S1' as well as S2's. The rotor arm and cap are different sizes on the electronic ignition distributor - not sure if the 'strib itself has other differences. (John "the nut" and I discovered this when trying spare rotor arms from a points car on his S2 electronic ignition car = no spark) - I think the original lucas caps were blue for electronic ignition spec?

Lotus used the sprung physical rotor arm as a rev limiter, and only went to an electronic rev limiter with the excel in 1983 and the AB14 ignition amplifer.

Lumenitions and AB14's are old and crap, and are easily bettered by fairly cheap stuff available new. I wouldn't bother with retro fitting a lumenition module to a points spec car - just buy a modern unit. I sound like their agent in this thread, but Powerspark sell kits that I think others on here have used. Megajolt and MSD has also been done succesfully on a 2 litre 907.

With regards to servicing the points, - yes, its a pain with the airbox on and access is tight. With the car at TDC and the timing belt still on, the Aux timing pulley is held in place, so you can mark the 'strib and remove it in the usual way. Its when the belt is off that it can become a bit of a 'mare as you have to time up the Aux pulley. It's not that complicated - no real pitfalls..

Be careful on a replacement distributor if you decide to go down that route - some of the "complete replacement" electronic ignition units aren't designed to be mounted on their side and will leak oil through the cap when used on a 907/912 engine as they don't have the necessary oil seal.

[Robbie]

Thanks that makes sense I have used powerspark on MGs  as a complete unit with electronics and rate them but you make a good point on it being fitted on its side in a lotus so to be careful distributor is designed for this. Today I managed to get the ignition fed resistance wire to read 7 volts to the ballasted coil, so connections correct, will fit new points and condensor and hopefully sparks up. If that works will stay with points unless needed to change to electronic. My rev limiting rotor seems in good shape very solid so hopefully ok for a few years. I see they are difficult to come by .Thank you for the heads up on distributor removal I could not understand the issues on forums now I do with belt off, thankfully mine is on..  If it runs I will celebrate by posting some pics of the car.

[Robbie]

director dan certainly the wavy line is the ballast resistor , funny is shows c2  leading to a. earth which made me think there is a separate module. . Thankfully today my resistance wire appears working as it reduced voltage to the coil, the indication to earth in the diagram may be to show the voltage only drops when a circuit is made to earth. 

[directordanw]

I’ve always got dizzy parts from Distributor Doctor - http://www.distributordoctor.com/

They have a great selection of their own replacement caps and rotors but they also offer a full rebuild service which might be the way forward if you do struggle to find a replacement horizontally mounted distributor. 

[black eclat]

C2 is most likely just a noise suppression capacitor.

KW is the ballast resistor.

[directordanw]

KW stands for Pink/White so possibly  refers to the high resistance wire that leads to the positive on the coil. The wiring diagram must bundle both these components together or was possibly drawn with the thinking that a ballast resistor wouldn’t be necessary. My S1 just had the coil, no resistor. 

[Dunc]

It is a high resistance pink wire on S1's. If there is an actual ballast resistor present, someone has taken a feed from the +12V ignition and ballasted it.

[Robbie]

Summary and thanks to all for contributions which I have put into this note. 

The Lotus electrical ignition system is very basic, but components need to be in good order. Add decent plug leads and spark plugs and there should be no issues. 

The diagram is accurate,.both for S2 and S1 (with the lumination excluded) . C2 is a noise suppressor, I have found the one that was on the old coil originally old radios probably still need it.

The S1 has a ballast coil (would test with an resistance meter at 1.5 rather than 3 for non ballast,) Using a non ballasted coil will still work but the coil will overheat and quickly damage the points and condenser , a common mistake leading to ongoing running problems.

There is a rev limiting rotor on the distributor. A Red rotor can be use but revs then will not be limited and potential dangers of engine and belt damage if revs exceeded. Rev limited rotor is marked 3500 and is hard to find but is well made, extremely sturdy and second hand is likely to be adequate, check condition.

The Pink sheaved wire is a thick single strand of copper which seems similar to 1.5 mm electrical wire  and acts a a resistor showing 7V ,Substitutes can be made up but voltage will require testing to find the appropriate thickness . This is very basic system which can be replaced by a purpose built resistor on ebay. They  are easy to fit but make sure they are connected in place of the pink sheaved wire (remove the resistance wire if still in place.)

!2v is supplied on starting from the direct feed on the starter solenoid to positive side of the coil which ceases  once engine stops cranking.

A continued feed comes from ignition when switched on  via the fuse box and is at approx  7v after passing through the pink resistance wire .

Keep the the oil filled coil  in an upright position, It should not become hot after use

Accuspark electronic modules seems acceptable ( ensure it is for the ballast coil applicable to the lotus model).

Additionally  rebuilding original distributor if required , (distributor Doctor provides a service) , 

A cheaper new distributor or combined electronic converted distributor could be purchased but ensure it can withstand working on its side without leaking and match the lotus specification (which seems unlikely).

Earthing plays a part, the wire to the side of the distributor can cause breakdowns and to the negative side of the coil. 

If you have not done so .and are unaware of the age of the points distributor cap and condenser, it is wise to renew them as they are cheap and it is safe to remove the distributor marking its position after putting rotor to No1 plug position, (number one is near the front of the engine.) providing all the belts are on. 

 

 

 

Edited April 17, 2018 by Robbie

[mikeeech]

Thanks for this detailed explanation. It will come in very useful to me.

[Drawfiler]

Just a word on timing, I had a breakdown when the clamp bolt allowed the spring to push the dizzy out of engagement.

i slackened off the clamp bolt and fired up the starter motor with a hut wire from the battery bypassing the switch, rotated the dizzy until it engaged and then twisted it until the engine fired and ran. This got me home until I could retire properly.

since this incident I just do the same when I have the dizzy off.