Tachometer problem after installing MSD ignition

[RJE]

I recently installed an MSD ignition system and an MSD Tach adapter. The Tach failed after about 20 miles; I'm now on my third Tach adapter and it's just failed again! Has anyone had the same problem and has a solution been found or is MSD just a supplier of rubbish kit?

[B.P.Bird]

RJE,
Probably get some helpful suggestions if you could explain what application you are dealing with. For example the later cars use the Ford EEC IV engine management system which uses a speed sensor to drive the tachometer. There are so many variables between coil and distributor specification that it is not surprising that compatibility problems arise.
For what my tuppence h'penny is worth you will not improve the original Ford ignition system whether that is the original twin point dizzie, the interim partial electronic system, or the later EEC IV. It is worth thinking about the A.C. le Mans entries that ran successfully for 24 hours with nothing more than the Ford Autolite twin point dizzie and the Ford yellow top coil
Barrie

[RJE]

Barrie, thanks for taking the time to respond. I replaced the Ford EEC IV with an MSD 6AL after several recommendations. On the dyno that proved to be worthwhile. However, I now have this tacho problem, which MSD say should be solved by their tach adapter. It's been wired as per their instructions and it works for a short while then fails. Either MSD has a quality problem, their wiring diagramme is wrong or there's a problem with the tach (which has otherwise working since 1989 without fault) beyond the fact that it doesn't work in its standard iteration with the new ignition system. I was hopeful that someone in the Club would have had the problem and know a solution. You're the only person to have responded, for which I am grateful, but that begs the question (backed up by the almost complete lack of activity on the foum in recent weeks) - what use is this forum and by inference what commitment within the club is there to support members?

[AndyMay]

My experience relates only to the previous duraspark incarnations so may be a red herring, but have seen similar issues with MSD conversions when the ballast resistor is eliminated. Just an avenue to consider.

Yes, this is the quietest owners forum I've encountered and has discouraged me joining the club.

[B.P.Bird]

RJE and Andy May,
I have been a bit tardy in joining this discussion by reason of attending Michael Trotter's wonderful A.C. Owners Club Hampshire event, based in Winchester. Quite a long round trip for me, which I also thoroughly enjoyed.
For what it's worth I am confident that the recent good weather has seen many members driving their A.C.s rather than engaging with this Forum. Of course joining in events does rather depend on Club membership....
Turning to the problem in hand I am rather puzzled by your comment that you have replaced the EEC IV with an MSD 6AL. This cannot be what you mean surely ? This MSD unit will only provide ignition - all the other parameters must still be provided by the EEC IV, or have I completely misunderstood the situation ?
Going back to basics it is helpful in setting up any machine, your engine in this instance, to make only one change at a time - forgive me if I am teaching Grandmother to suck eggs. For example were it me fitting a new ignition system it is almost certain that I would take the opportunity to replace the other relevant components; sparking plugs, HT wires dizzie bearings and cap. If you did a thorough job then the improved dyno readings cannot be claimed by any single component. Maybe it was only the 6AL that you installed in which case it might be the reason for the improvement: On the other hand the 6AL might simply be masking another deteriorating symptom ?
So I have to point out something which you will find in the Ford Service manuals, but in very small print: 'Sensors deteriorate over time and should be replaced.' This is particularly unhelpful in that no timescale is mentioned, in fact you could say that it states the bleed'n obvious. However on CRS 9520 the sensors were all around 24 years old when I instituted a replacement policy - one at a time. This restored performance and smoothness bit by bit. In particular the O2 sensors and the Throttle Position Sensor made a big difference.
None of the foregoing is directly relevant to the above MSD problem, but might be worth a thought when you are planning the way forward to improve performance - building on shaky foundations never works...
So if the tachometer works for a time, whilst the MSD adapter survives, then the adapter output must be compatible in form. As you have determined that it is the adapter which is failing could you use a test meter to determine how much current the tachometer is taking ? It seems possible that the 1989 tachometer is too low a resistance for the adapter which is getting fried by a higher than spec. current ? I think the 1989 tacho. could be 'Autometer' not Smiths, but you should be able to read that on the dial (more small print) in which case a bit of research would tell you what input the tachometer uses. The other line of attack would be to find the output from the EEC IV Ignition Control Module which drives the tacho and measure that. I wish I could tell what the standard set up was, but the Ford manuals are entirely opaque on the matter.
Finally, with apologies for my verbosity and, admitting to be somewhat cynical, is there any connection between the advice you received to purchase the MSD 6AL and the dyno operator who reported an improvement ?
Barrie

[AndyMay]

Hello Barrie, just a quick point on the use of cars; I indeed did a lovely road trip around the Scottish Highlands recently in my 428 and linked to a write up regarding that in the 428 section (admittedly I had to link to another forum as I had no way of hosting photos here). Not one single comment or word of encouragement? It surprised me nobody had any interest but also confirmed what someone had suggested to me regarding the focus of the club being Cobra and Ace enthusiasts.

Anyway, hopefully your wisdom regarding RJE's issues has been useful.

[RJE]

Barrie, thanks for your follow up, I appreciate the advice. I replaced a Ford ignition system but from what you say it wasn't the EECIV, the car had a Stage 3 engine fitted by the factory after delivery in 1989 and uses a Holley. All the ignition system components were replaced. Northampton Motorsport who provided the dyno time and set up didn't do any of the restoration work. The tach is Autometer, from what I'm led to believe I wouldn't be having any of this problem if it were Smiths. An internet search suggest that the incompatibility problem is common but most suggest that the adapter sorts it out, albeit that some commentators question MSD's wiring diagramme - if only that were true for mine. Thanks again.

[Flyinghorse]

I would conclude if you have burnt through 3 MSD tach adaptor in short order then the install wiring is not correct ( despite it working for 20 or so miles), not MSD suppling 3 faulty components.
There's a few cautionary warnings( for msd 6)  in the Tach adapter notes I've attached , and you would need to know if your tach is current or voltage triggered to wire it correctly.
Have you tried MSD's technical department?

[Flyinghorse]

You won't have a EEC1V system if it's carburetted as there's no injectors to control or MAF/ tps etc.

[RJE]

Many thanks for the information. I have the advice sheet you reference and have checked.

[Flyinghorse]

I also noticed theres two tach adapters (8910 and 8920 ) each specifically required,depending on how you are triggering the MSD 6AL