Anyone else here using an MSD ignition?

Are you using MSD wires?

 

You may have the wrong ohm coils

 

MSD is VERY sensitive to coils. I once lost an important race because my MSD coil didn't match my MSD box. (my fault)

 

I'm running 3 of those now. 2 x 6A's in a 308 and a 7AL in a BB. Knock wood - I'd believe they are harder on ignition parts, but not drastically IMHO.

Following the basics I understand about creating a spark: Voltage rises until it finds ground, or is bled off by carbon (mildly conductive) fowling, or ceramic contamination such as that created by running a wire brush across the spark plug insulator. That's why one should never clean a plug with a wire brush. Anyway, there are more sparks per firing which would make sense to cause more wear, but again, what I've seen seems ok.

This is the best I can answer your concern. BTW - I have not changed coils. I have tracked the 308, and again, (knock wood) all seems good.

Are both caps wearing the same? Were wires etc fresh to begin with? The stock Ferrari ignition makes a pretty strong spark.

 

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So after 5k miles, plugs, wires, cap, rotor are non-servicable? let's start with the easiest piece - the spark plug. At 5k miles, I'd expect to see wear. If the plugs are platinum, I'd expect the center electrode to be pretty much gone. If Iridium the edges should have lost their edge, and gap could be off. Also, you can control wear on the plug to a large degree by heat range selected. Hotter are less prone to foul, and you'll be less likely to get that stumble after driving in heavy traffic; but, more wear. Too cold - last like "iron", but foul if idling a few minutes in your driveway (of course engine depending).

Cap & rotor ?? What looks bad? Are the contacts really eaten away? Signs of overheating at contacts?

Wires? Did you see external arcing (shows up at night)? Burn thru spots from voltage killing the dielectric?

I see your concern. 5k miles is a bit young for ignition parts to need replacing (except plugs - I've seen plugs go in really short periods). But again, are parts showing wear or not usable?

 

That's a BINGO. I went through this on a '50 Oldsmobile with a 1962 394 Olds engine stuffed in it. My buddy bought the wrong MSD coil and it fried the cap, wires,and plugs in no time.

 

Get the correct ohm coils for the MSD unit and you will be fine. We run into this all the time.

 

Why not just buy the MSD coil? It's made to specifically match their unit. Call them. They'll tell you which one to use. Taylor wires work very well on my 400i. Jq.

 

MSD 6A is a capacitive ignition, it uses the coil as a step up transformer so the resistance (ohm) is not relevant, but the winding ratio is as it affects the coil's output voltage.
Capacitive ignitions have a much higher output voltage than inductive (transistor, points) ignitions, so the cap, wires and rotor finger should be in good condition to avoid arcing. If in doubt, replace the cap/wires and rotor and you should be fine with an MSD 6A setup.

Would recommend to install a MSD Blaster II coil with the MSD 6A series.

Good luck,
Adrian

 

The Multi Spark Discharge (MSD) 6A only good up to about 4000 rpm then after that it becomes single spark. I am looking for a unit that provides Multi Spark all the time, anyone knows of any?

 

Hi Mike,

I thought that the multipul spark went to single at maybe 3k rpm and have never heard of a multipul spark up through redline. Part of the problem is that it takes more time to make the MS happen.

I have run a Norwood conversion to a single distributor with a cheapo chevy 8 cyl cap, ($16-18 bucks), Blaster 2 coil, msd wires and AC plugs with a gap opened to 45 or 50 thou.
Keep the extenders in god condition by maintaining the rubber seal on top.

Pulls to 8k strongly, no ignition issues even on the track with continued high rpm and heat.

I have used MSD6AL on both the ferrari and the much abused toyota work truck, (just turned 400,000 miles).

my .02
chris

 

I went down the path of looking at plug gap relation to distrib/rotor gap. I called Mallory and MSD. I tried to relate some concepts of impedance matching analogies to get the spark energy to the plug. No one could or would tell me the science behind it.

The MSD link below makes a lot of sense regarding stressing the components from excessive voltage.
IgnitionInfo.com - for more performance!

Theories? Support? Alternate theories?

 

Pertronix make a system called Second Strike. It piggybacks the OE ignition so you get the OE inductive spark first but then gives a second capacitive spark. You can adjust the crank angle that the second spark occurs at and there is a soft touch rev limiter built in as well. I believe it is unique in the industry. Works on 4, 6 and 8 cylinder engines. Not cheap though.

 

A 45 - 50 /1000 gap is pretty large. Something to keep in mind is voltage goes up with larger gap. The collapsing field generates voltage until it finds ground. Think of lightning or vacuum interupters (used by utility companied to shunt off voltage spikes). Higher voltages really do take a toll on dielectric parts. Typical Ferrari plug gap is .020", so I believe I've bumped up my MSD cars to .030 - .032, and I would toss a plug if it was beyond .035. I don't think I'd go to 45 for this application (imho).

 

Good day 2Dinos,

Perhaps you are simplifying this to prove your point... and so I will add a bit more to "meat" to it... The secondary voltage (i.e. plug voltage) does not increase indefinitely as your sentence above implies. For ignition coil based ignition systems, the secondary voltage is directly related to the turns ration of the ignition coil (which is really just a transformer) and so it does have a limit (the secondary voltage maximum is the turn's ratio x the primary voltage max). The secondary voltage max may or may not ever be reached, as this is dependent upon when the spark plug fires. The firing, as you mentioned, is directly related to the spark plug gap... The bigger the gap the larger the (secondary) voltage is required in order to increase the electric field between the spark plug terminal and its outer ring (ground) to a point where the field ionizes the air between these points and thus causing a spark. So, there will be a point where the gap may be too large for the maximum voltage available (to create an E field large enough to ionize the air) and so the plug does not fire and/or the available energy may be discharged through another weak point in your high voltage portion of your ignition system (i.e. faulty distributor, wires, etc). The key point is that the high voltage energy will discharge through the path of least resistance which may or may not be the spark plug ... and thus why the plug gap plays such an important role...

Cheers,

Sam

 

Hi Sam,
+1. I concur. Now where it gets interesting is the whole power relationship for the spark. MSD gives more opp'y for unburned fuel to light, and the ramp in primary voltage gives the ramp up in coil secondary V. But where it gets fuzzy (to me) is the whole voltage squared / resistance relationship to get power. I mean- What is the "resistance" for a spark gap??? With basic ohms law, the higher voltage would create higher current flow for a given spark gap and this is where the power goes up (Another analogy: electric welding - the electrode gap determines voltage, and current controls heat and "size" of arc) so it's kind of wild to consider how the sencondary winding will try to up the voltage to its theoretical coil relationship until the spark fires (hopefully at the plug gap Vs a bad plug boot etc), and the spark energy is increased due to the current flow.

More MSD experiences:
1. When I put MSD on my car, I left the plug gap at .020. The equipment I used showed basically the same plug voltage, but it sure idled better, started quicker, and most importantly, emmissions dropped.
2. Using resistor wies + resistor plug extenders + resistor plugs was too much, and made external tach readings impossible (showing I believe that resistance limits the current and decreases the corresponding B fields to pick up). And by the way - this must decrease spark energy.

Thanks for the awesome discussion! I was not able to get this level of electrostatics physics from the manufacturer.
Bruce

 

Good day Bruce,

You are most welcome!

In regard to the "power" aspect of your comment... The power supplied to the plug is not based upon the voltage and plug resistance, but is from the Magnetic field initially generated by the primary side of the ignition coil (1/2 x primary coil Inductance x current squared or 1/2Li^2) and then collapsing inducing this energy (ignore losses for now) onto the secondary side of the windings. So, if we increase the current on the primary side (either via a current source or increasing the primary coil voltage) the magnetic field increases and thus more power will be transferred to the secondary windings/circuit. Secondly given the relatively low frequency of the ignition system (~ 4000 Hz or so max) one can generate multiple 1/2Li^2 power pulses which in essence provides more "power"/Energy over a given time period within the combustion chamber (the piston moves very, very slowly in comparison to the movement of electrons ).

As for the gap... well, the gap distance affects the breakdown voltage or the point where the space between the gap will ionize the air and a spark occurs and all of this energy is transferred (I seem to remember that the breakdown voltage is something like 6KV/mm in air... Which is probably in the same magnitude within a combustion chamber which is pressurized and is an air/fuel mixture). So, if one has more energy available one may wish to have a slightly larger gap in order to accumulate more charge (E Field) so that the energy transferred during a spark would be larger. I would have to model the whole system electrically and analyze it using low level principles, but I think my comments so far are not too far off. Perhaps someone who has already done this, etc can comment or correct any errors/assumptions I have made?

As for MSD other systems and how they affect the other equipment... This primarily has to do with EMI (electromagnetic Interference). EMI is directly related to frequency, but more importantly more to do with the "edge" rates (how fast a voltage goes from one voltage level to another) of the signal. The faster the "edge" rates and/or frequency the increase in the level of harmonics generated... which are what usually causes the issues. Other factors such as the wiring (primary and secondary) and its physical layout/construction also creates issues, as these elements can become antennas for these harmonics....Anyway I digress, as this is a whole other discussion for those that do not fall asleep too easily

Cheers,

Sam

 

Keep in mind that this only applies to inductive ignitions. Capacitive ignitions such as the MSD 6 series discussed here store their energy in a capacitor (hence the name) and not in a magnetic field, as with inductive ignitions. Typical max frequency (ignition discharge rate) is around 400-500 Hz for an inductive setup.

Best,
Adrian