I thought I`d try and bring together as much of the information as possible to make it a bit more accessible to anybody considering MSD in the future.
Originally my car (1968 911) was fitted with Kettering ignition. Named after its inventor, Charles Kettering, it was first fitted in Cadillacs in 1910. A simple points and coil system, it was revolutionary in its day but by the
sixties with the advent of higher revving engines, it was starting to show its limitations. With this inductive ignition, the coil must store and step up the voltage to maximum strength in between each firing. At higher revs there becomes less and less time to charge the coil to full capacity and the voltage for the spark falls short just when you need it the most. Add to this the problem of old wiring that has, over many years and probably millions of cycles, tempered to become less conductive, you can see why Kettering is probably not the best system for lighting the fuel/air in the cylinder of a 911 engine.
Similarly points can be problematical. With care the gap and dwell can be set accurately but in time these values can go awry and eventually the points can pit/erode and need replacing. If that`s not bad enough, if there is any play in the distributor shaft, it will wobble at higher revs causing the points to “bounce”, completely ruining the timing of the spark.
So the plan was to address both these shortcomings from two directions, a bit of a pincer movement.
Firstly the MSD itself. An American company, MSD offer a whole range of ignition units. The one I chose was the 6AL. It works on the capacitive discharge principle (CD) in a similar way to the CDI systems Porsche fitted to their cars from 1969 onwards. CDI, as its name implies, features a capacitor which is charged with 460 -480 volts in less than a millisecond and
the voltage sent to the coil is at full power, even at higher revs.
Where MSD differs from the original Bosch CDI, is that it produced not one but multiple sparks (hence Multiple Spark Discharge) for each firing of the plug. These multiple sparks do decrease as the revs increase, and at about 3000 rpm there is only enough time for one spark but it`s a much fatter spark than Kettering can deliver and it always lasts for 20 degrees of crankshaft rotation.
Here`s what a MSD 6AL looks like, it`s about 8” long 4” wide and 2” deep.... and yes unfortunately it`s bright red. I`ve read you can get black ones but I couldn`t find one.
http://www.msdignition.com/Products/Ign ... ntrol.aspx
Next was a coil to suit the MSD. The one you need is the MSD made anti vibration coil. This coil can be mounted horizontally in the original clamp, as a direct replacement for your original coil. Unfortunately the MSD coil comes with a large shiney sticker... fortunately this sticker peels off, leaving a pretty acceptable plain black casing. I should add, the standard MSD coil is oil filled and must be mounted vertically to avoid bubbles in the oil exposing the windings and overheating. The anti vibration coil is resin filled and can be mounted any which way.
The last thing I bought from MSD was a Tach adapter, part number 8910 for use with either Pertronix or points. There is a chance that your tachometer will work with the new signal the MSD sends, some do, some don`t. Mine didn`t until the tach adapter was wired in, then it worked fine.
Then, new plug leads. MSD state in their bumf that their ignition systems should not be used with solid core plug leads (Berus) They suggest spiral leads and the general consensus on the forums is to use Magnecors. I bought the black 7 mm Electrosports 70 leads, as the fatter brightly coloured leads they supply weren`t really right for my engine bay. Even the black leads had white lettering down their length, which isn`t very original looking but you can`t have everything.
http://www.magnecor.co.uk/productinformation.htm
Addressing the shortcomings of the points next on my shopping list. I opted for Pertronix. Pertronix replaces the points and distributor capacitor completely with a small plastic ring containing 6 magnets that slips over the distributor shaft under the rotor arm. As the distributor rotates these magnets are read by a small box that is fastened down to the plate where the points used to live. With Pertronix there is no dwell angle to set and any play in the shaft becomes unimportant. (within reason)
I should say here that the MSD will work perfectly well with points. I`ve spoken to many people who prefer points and are dubious about the longevity of the plastic, new fangled Pertronix. Personally, I decided to give the Pertronix a try. It`s a brave new world.
It`s important to buy the correct part for your distributor, they are supplied in the UK and rebranded Aldon Ignitors. I found Aldon to be very helpful.
http://www.aldonauto.co.uk/shop/product ... 39&P_ID=91
So first things first. I pulled the old plug leads and replaced them with the Magnecors. The effect was dramatic... in a favourable way, smoothed the engine out and tellingly the terrible interference I had on the radio was all but gone. It seems the old Berus were letting quite a bit of electricity stray away.
Next was mounting the MSD box and tach adapter. If you want to try and retain the original look of your ignition panel and avoid this...
...there seems to be 3 options. Either behind the floorboard in the passenger footwell, under the passenger seat or on the firewall in the engine compartment. In the footwell is good but you have to extend every wire then route them back through the tunnel. Under the seat is ok but depending on which seats you have fitted, it can be too tighter fit. I opted for the fire wall, there is some discussion about the MSD getting too hot here, but I don`t race my car and there seems to be a general agreement that even if I did, it`s perfectly fine to mount it here.
I first mounted a 3mm alloy plate to the firewall using vibration mounts suitable for fuel pumps, cheap on ebay and then screwed the MSD and tach adapter to it. Fitted in this position, all the leads are long enough and when the air filter housing is back in place you really don`t notice the installation. You`d notice it even less if it was black.
Then onto the connecting up. It`s all pretty straight forward. The original Kettering ignition schematic looks like this, just for reference,
Now when I got to my car, before the MSD install, it looked slightly different. Because there was a later coil fitted, the ballast resistor had been bypassed and it`s a different type... It`s the white rectangular block with the black clip at the top, wired at only one side. That connection is the Switched ignition connection. You don`t need a ballast resistor with the MSD but I left it in place for nostalga`s sake. As you can see, my engine compartment is pretty nostalgic.
The schematic looks like this, the only difference being the Ballast resistor connection.
So that`s how things lie before you start, this is how the MSD fits in.
Or if you prefer...
Pretty straight forward really. The instructions that come with the kit are comprehensive, even giving you a “Prestart check list” to settle you before the off. The thick red wire that`s shown in the MSD diagram going to the Positive battery terminal was, instead, taken down from the engine compartment to the permanent live on top of the starter motor. The thick black negative wire was terminated on the chassis ground behind the fuel pump. And taking advise, I also put an earth strap to the alloy mounting plate which in turn gives a good earth to the MSD case. It seems a lot of niggley MSD problems are down to a weak earth. All other connections were made using the ample supply of connectors supplied with the MSD and then sealed with heat shrink tubing.
MSD recommend you re gap the spark plugs to between 0.04” -0.05”, I tried it at 0.045” for now.
And after all that.. how is it ?
The difference is remarkable, the power is much fuller, more rounded... I`m not sure there`s any more of it, it`s just more usable. I was trying to explain to the apprentice how different it felt (fuller, rounder, more body... sounding like some waffling wine fool) And when he got back after taking it for a good thrashing, he grinned and said “ Torque`s the word you`re looking for” So there you have it, more torque, better idle and most importantly for me, because this is what I`ve been chasing for two years, much smoother acceleration, right up through the revs. There`s none of that confusion at the top end as the old Kettering ignition desperately tries to burn all the fuel the Webers are throwing at it.
My ignition panel, for all intents and purposes, remains the same but for the new black coil, which really doesn`t look out of place. I`m taking the opportunity to tidy all the wires and to get rid of all the nasty black tape, I`ll post an after shot soon.
Kenikh was right after all. It was he, who on a number of occasions, posted on the American forums, recommending the upgrading of early ignitions. I railed against it, determined that if only I could get my car back to showroom spec, all would be well. I bought distributors, I had distributors recurved, I had my Webers completely rebuilt and the manifolds welded, I tried hotter plugs and colder plugs all with different gaps and nothing has had an effect like fitting MSD. A year after my car was built, Porsche themselves realised the shortcomings of Kettering ignition, introduced CDI and never looked back.
This is a very useful thread by John over on Pelican, It comprehensively covers early the early ignition system and I found it a great help.
http://forums.pelicanparts.com/porsche- ... trics.html
As anyone who knows me will tell you, I am no expert in these matters, so if you find any of the above information suspect, please let me know, so I can edit accordingly.
Regards, Mike.
