MSD ignition with a Lucas dizzy

[sidecar]

Hi Guys,

I'm going to fit an MSD 6A-2 programmable ignition system to my car as it has some features that I'd like to use. Has anyone managed to use the standard Lucas dizzy pickup to trigger one of the MSD 6 range of ignition units? (Just the pickup, not using the Lucas amp)

Also does anyone know the resistance of the standard 35DML8 pickup, mine reads 3k ohms.

Cheers!

[DEVONMAN]

Hi Guys,

I'm going to fit an MSD 6A-2 programmable ignition system to my car as it has some features that I'd like to use. Has anyone managed to use the standard Lucas dizzy pickup to trigger one of the MSD 6 range of ignition units? (Just the pickup, not using the Lucas amp)

Also does anyone know the resistance of the standard 35DML8 pickup, mine reads 3k ohms.

Cheers!

I tried this once on the bench as I thought it would be a good "get you home" trick if the ignition amp sizzled on the road. The MSD 6 did fire using the mauve/green connections but some times when the reluctor stopped next to the pickup, I got a continuous buzz of sparks from the coil. Never understood `why so took it no further. Maybe the pickup wires were round the wrong way. At the time I didn't realise they were polarity sensitive.

I would also be interested to hear if someone has got this set up working.
Regards Denis

[sidecar]

Hi Guys,

I'm going to fit an MSD 6A-2 programmable ignition system to my car as it has some features that I'd like to use. Has anyone managed to use the standard Lucas dizzy pickup to trigger one of the MSD 6 range of ignition units? (Just the pickup, not using the Lucas amp)

Also does anyone know the resistance of the standard 35DML8 pickup, mine reads 3k ohms.

Cheers!

I tried this once on the bench as I thought it would be a good "get you home" trick if the ignition amp sizzled on the road. The MSD 6 did fire using the mauve/green connections but some times when the reluctor stopped next to the pickup, I got a continuous buzz of sparks from the coil. Never understood `why so took it no further. Maybe the pickup wires were round the wrong way. At the time I didn't realise they were polarity sensitive.

I would also be interested to hear if someone has got this set up working.
Regards Denis

Hi Denis,

Thanks fro the reply, it sounds more promising than "no it won't work" so that's good!

Can you remember which way round you connected the wires? (pushing it a bit , I know!)

I wonder whether increasing the air gap would have sorted it out?

The final thing that was going to try was to buy an MSD pickup which they sell as a spare part then fit it into my Lucas dizzy. The only thing about doing this is that the MSD reluctance wheel a quite different to the spikey Lucas one so it might not produce the right signal.

Cheers,

Pete

[DEVONMAN]

Pete,
In my notes I have a postage stamp sketch of a 2 pin ign amp. Of the 2 pickup connections on the back, the +ve connection is furthest from the 2 spade connections. If you transpose that onto the dizzy body then I think it's the orange wire inside the dizzy that is +ve. But I'm not 100% on that.
From what I understand it should work either way round but not efficiently if connected the wrong way round, if that makes sense.

I'm sure one of the electrical boffins on here will be able to explain.

Regards Denis

[Robrover]

Before I installed the Scorcher dissy, I had a Lucas Opus (early SD1) dissy fitted with a Lumenition optronic chopper wheel which was wired to an MSD6 CDI via a small "Lumenition to MSD" module that MSD sent me (I don't think they're available still). This worked well.

[DaveEFI]

Hi Guys,

I'm going to fit an MSD 6A-2 programmable ignition system to my car as it has some features that I'd like to use. Has anyone managed to use the standard Lucas dizzy pickup to trigger one of the MSD 6 range of ignition units? (Just the pickup, not using the Lucas amp)

Also does anyone know the resistance of the standard 35DML8 pickup, mine reads 3k ohms.

Cheers!

3k (approx) is correct.

It would be better to trigger off a crank sensor and just keep the dizzy to switch the spark, though.

[sidecar]

Hi Guys,

Thanks for your replies and confirming the resistance of the pickup.

I don't have a crank trigger so I'm sort of stuck with the dizzy! I intend to lock the bob weights and use the latest MSD A6-2 programmable unit to create an advance curve.

The way I see it at the moment I have some options:-

1. Use the Rover pickup directly. (The one that I would like to use).
2. Use the Rover dizzy and reluctance wheel but fit an MSD pickup.
3. Use the Rover dizzy and either use the lucas or an after market amp to fire the MSD box.
4. Fit some sort of optical chopper wheel into the Rover dizzy and use this to fire the MSD. (This still might need some sort of amp)
5. Fit some sort of crank trigger. (Might actually be the best option!)

I've emailed MSD directly and joined the MSD forum (not posted yet). I'll keep you informed!

Cheers,

Pete

[DEVONMAN]

Hi Pete,
I have run your option 3 with locked out bob weights and it worked fine.
I went for the dizzy rather than a crank sensor as the dizzy gave me some vacuum advance on light throttle and hence better milage.
Regards Denis

[sidecar]

Hi Pete,
I have run your option 3 with locked out bob weights and it worked fine.
I went for the dizzy rather than a crank sensor as the dizzy gave me some vacuum advance on light throttle and hence better milage.
Regards Denis

Just checked out how much the crank sensor is....it's nearly as much as the MSD box its self!!!

Option 3 is OK but I don't want to use the Lucas amp, I've blown a couple and even when they do work I don't think that they don't give a clean signal. I believe this because I had a Clubman rev limiter fitted at one time, it would cut in and out due to it seeing 'extra' pulses. I also have a Summit RPM window switch for my NOS system, that also could not read the signal well. (I fitted a zenzer diode which cleaned up the signal). I could use one of those after market amps that the 'sticky' thread shows how to setup.

Somehow it just seems a bit daft to use an amp to signal another amp....I'm a fussy bugger, I know!

Then again running long pickup wires from the dizzy all the way back to the MSD (about 1.5-2 metres) may not be too clever either! At least the 'two' amp setup would have a strong signal back to the MSD as long as the first amp is right next to the dizzy.........Hmmmm?

Aha, another thought, option 3 would allow me to set the inital advance and get the engine up and running just by using the first 'pre-amp' to power the HT coil directly, I could then plug in the MSD!

Right, that's what I'm going to do!

Cheers everyone!

[DEVONMAN]

" Aha, another thought, option 3 would allow me to set the inital advance and get the engine up and running just by using the first 'pre-amp' to power the HT coil directly, I could then plug in the MSD!"

Right, that's what I'm going to do!

Cheers everyone![/quote]

Ah! but don't you need to move the locked out dizzy forward 30 odd degrees (before you connect the MSD) and get the MSD to vary the retard between 800-3500revs.

Regards Denis

[DaveEFI]

One gotcha when using a locked advance dizzy is you need to phase the relationship between rotor arm and plug lead contacts accurately, as it no longer varies with the spark advance.

[DEVONMAN]

One gotcha when using a locked advance dizzy is you need to phase the relationship between rotor arm and plug lead contacts accurately, as it no longer varies with the spark advance.

I don't thing the relationship is affected by the bob weight position as the rotor, reluctor, pickup and cap have a fixed relationship. However the vacuum advance does change the relationship because the baseplate moves as does changing the pickup gap.

Regards Denis

[sidecar]

Guys the rotor arm mis-alignment is bad to start with on the Rover dizzy, I think is one of the reasons why cheap rotor arms fail!

I've modified a rotor arm by grinding out the location peg and fitting a new one so that at least part of the rotor arm is directly in line with the correct HT post between the 12-32 degrees range that I use. The vac system would also through another spanner into the mix but as it does not work too well with the Eddy 500 carb so I don't use it!

As the MSD unit that I'm going to fit only has retard curves built into it I'll set the static 'locked' advance to 32 degrees. I'll set the MSD to 'add' 25 degrees retard (the max) from 0 to 600 RPM. This will give a cranking figure of 7 degrees.

The retard will then be reduced from 600 to 800 RPM to 20 degrees which will give 12 degrees total advance. (The lump ticks over at 850 RPM)

The 20 degrees 'added' retard will remain until 1000 RPM at which point it will gradually reduce to zero retard at 3000 RPM (Or what ever figure I go for).

The leading edge of the rotor arm will need to line up with the HT post at tickover so that by the time the MSD has added its retard hopefully the trailing edge of the arm will still be in line with the post!....well that's my theory!

The MSD has a cool feature which I want which is the NOS retard, basically whenever the NOS system fires I can automatically knock out some of the timing.

Then there's the launch control to play with....

[DEVONMAN]

Hi Pete,
You've got the old grey matter working now.

I think it's the trailing edge of the rotor that needs to line up at tickover and as the MSD reduces the retard with engine speed the actual spark will happen towards the leading edge of the rotor.

But whatever, setting up the MSD and road testing is great fun.

Regards Denis

[sidecar]

Hi Pete,
You've got the old grey matter working now.

I think it's the trailing edge of the rotor that needs to line up at tickover and as the MSD reduces the retard with engine speed the actual spark will happen towards the leading edge of the rotor.

But whatever, setting up the MSD and road testing is great fun.

Regards Denis

Hi Denis,

I'll have to have a think about this!

I guess if the pickup sends the 'fire' signal to the MSD just as the leading edge of the rotor arm lines up then this would be OK because the MSD would 'twiddle its thumbs' for a few milli seconds in order to create the regard figure required. During this time the rotor arm would continue round therefore hopefully the trailing edge would still be in line with the post by the time that the MSD decides to fire the plug.

I should be able to work out when the pickup is sending the signal by locking the dizzy and running the engine with the Lucas style amp. I could set the timing to say 10 degrees BTDC then stop the engine and crank it round to 10 degrees BTDC. The dizzy must then be at the point where the pickup triggers.

Like you said, its all good fun! I've already downloaded the software that is used to control the MSD and create the timing curves. I ain't got a clue whether they are any good but they look nice!

Cheers,

Pete