MSD Ignition Coil
Just another of my mis-informed posts...
Yesterday I replaced my stock coil with an MSD. To my great surprise, the car now runs noticeably smoother between 6K and 7200.
Note: I don't know that smoother has to equate to measurably more powerful, as it seems to me that a few milliseconds faster ignition in one cylinder at high rpm might be audible to my ear (which is well-trained), but not measurable on a dyno, which is an extremely crude instrument for an ignition analyzer.
Anyway, the point of this post is simply to state that the reason I replaced the stock coil is that one of the terminals was showing evidence of arcing. A small black spot - a bit smaller than a BB - was visually apparent, and that terminal looked a bit dusty.
IMHO, this is not evidence of any sort of chemical corrosion, but instead is the result on high-voltage arcing on a plated surface. At Mini-Madness, George showed me two other stock coils that he had replaced: one had a spot a bit larger than mine, and one had a whole terminal almost completely blackened. In all of these cases, I could not see any evidence of chemical corrosion, but of electrical "erosion". The dust that appears on a damaged terminal is almost certainly vaporized metal, not chemical residue, which would be whitish.
So the reason why I believe I am getting slightly better high-rpm ignition is that one terminal on the coil was not making a good connection. With luck, the brass terminals on the MSD will do better, as brass is a better conductor than nickel-plated steel.
So, the next issue is whether replacement with a stock coil would work as well, and my guess is that it probably would.
So bloody what?
The MSD, which looks like it was made on the exact same machine as the stock coil, cost less, and might work a hair better. Seems like enough justification for choosing the MSD-branded version to me...
Note: I don't know that smoother has to equate to measurably more powerful, as it seems to me that a few milliseconds faster ignition in one cylinder at high rpm might be audible to my ear (which is well-trained), but not measurable on a dyno, which is an extremely crude instrument for an ignition analyzer.
Anyway, the point of this post is simply to state that the reason I replaced the stock coil is that one of the terminals was showing evidence of arcing. A small black spot - a bit smaller than a BB - was visually apparent, and that terminal looked a bit dusty.
IMHO, this is not evidence of any sort of chemical corrosion, but instead is the result on high-voltage arcing on a plated surface. At Mini-Madness, George showed me two other stock coils that he had replaced: one had a spot a bit larger than mine, and one had a whole terminal almost completely blackened. In all of these cases, I could not see any evidence of chemical corrosion, but of electrical "erosion". The dust that appears on a damaged terminal is almost certainly vaporized metal, not chemical residue, which would be whitish.
So the reason why I believe I am getting slightly better high-rpm ignition is that one terminal on the coil was not making a good connection. With luck, the brass terminals on the MSD will do better, as brass is a better conductor than nickel-plated steel.
So, the next issue is whether replacement with a stock coil would work as well, and my guess is that it probably would.
So bloody what?
The MSD, which looks like it was made on the exact same machine as the stock coil, cost less, and might work a hair better. Seems like enough justification for choosing the MSD-branded version to me...
Last edited by OldRick; Jul 16, 2008 at 11:42 AM.
Yesterday I replaced my stock coil with an MSD. To my great surprise, the car now runs noticeably smoother between 6K and 7200.
Note: I don't know that smoother has to equate to measurably more powerful, as it seems to me that a few milliseconds faster ignition in one cylinder at high rpm might be audible to my ear (which is well-trained), but not measurable on a dyno, which is an extremely crude instrument for an ignition analyzer.
Anyway, the point of this post is simply to state that the reason I replaced the stock coil is that one of the terminals was showing evidence of arcing. A small black spot - a bit smaller than a BB - was visually apparent, and that terminal looked a bit dusty.
IMHO, this is not evidence of any sort of chemical corrosion, but instead is the result on high-voltage arcing on a plated surface. At Mini-Madness, George showed me two other stock coils that he had replaced: one had a spot a bit larger than mine, and one had a whole terminal almost completely blackened. In all of these cases, I could not see any evidence of chemical corrosion, but of electrical "erosion". The dust that appears on a damaged terminal is almost certainly vaporized metal, not chemical residue, which would be whitish.
So the reason why I believe I am getting slightly better high-rpm ignition is that one terminal on the coil was not making a good connection. With luck, the brass terminals on the MSD will do better, as brass is a better conductor that nickel-plated steel.
So, the next issue is whether replacment with a stock coil would work as well, and my guess is that it probably would.
So bloody what?
The MSD, which looks like it was made on the exact same machine as the stock coil, cost less, and might work a hair better. Seems like enough justification for choosing the MSD-branded version to me...
Note: I don't know that smoother has to equate to measurably more powerful, as it seems to me that a few milliseconds faster ignition in one cylinder at high rpm might be audible to my ear (which is well-trained), but not measurable on a dyno, which is an extremely crude instrument for an ignition analyzer.
Anyway, the point of this post is simply to state that the reason I replaced the stock coil is that one of the terminals was showing evidence of arcing. A small black spot - a bit smaller than a BB - was visually apparent, and that terminal looked a bit dusty.
IMHO, this is not evidence of any sort of chemical corrosion, but instead is the result on high-voltage arcing on a plated surface. At Mini-Madness, George showed me two other stock coils that he had replaced: one had a spot a bit larger than mine, and one had a whole terminal almost completely blackened. In all of these cases, I could not see any evidence of chemical corrosion, but of electrical "erosion". The dust that appears on a damaged terminal is almost certainly vaporized metal, not chemical residue, which would be whitish.
So the reason why I believe I am getting slightly better high-rpm ignition is that one terminal on the coil was not making a good connection. With luck, the brass terminals on the MSD will do better, as brass is a better conductor that nickel-plated steel.
So, the next issue is whether replacment with a stock coil would work as well, and my guess is that it probably would.
So bloody what?
The MSD, which looks like it was made on the exact same machine as the stock coil, cost less, and might work a hair better. Seems like enough justification for choosing the MSD-branded version to me...
any chance you dyno the car with both coils to show the difference?
thanks for the butt dyno result
But go ahead, respond and have the last word again - we know you've just gotta...
Last edited by OldRick; Jul 16, 2008 at 11:41 AM.
And another thing - coil installation tip
Just got back from the car. It occurred to me that if an electrical connection is arcing, it will be spraying metal vapor all over the place, not just on one of the surfaces of the connection...
So I got out the Deoxit, cleaned the wire connectors at the coil end with Deoxit and a q-tip, and sure enough, the connector on the wire where the arcing had occurred was filthy with the same black stuff that had been on the coil connector.
Left in place, this vaporized metal and metal oxides would add to the resistance of the connection, and likely lead to future arcing, so there's an angle on the "they all fail again even after replacement" issue...
So, clean out these connectors or use new wires if you are replacing a coil.
The other three wire connectors were clean as a whistle, so I view all this as additional evidence that the issue is arcing, not chemical corrosion.
BTW, George M. tells me that it's almost always the cylinder #3 coil connector that fails first - the one nearest the (US) driver - so if you want to do a quick check on the condition of your coil, check that one for the dreaded black spot and dust.
So I got out the Deoxit, cleaned the wire connectors at the coil end with Deoxit and a q-tip, and sure enough, the connector on the wire where the arcing had occurred was filthy with the same black stuff that had been on the coil connector.
Left in place, this vaporized metal and metal oxides would add to the resistance of the connection, and likely lead to future arcing, so there's an angle on the "they all fail again even after replacement" issue...
So, clean out these connectors or use new wires if you are replacing a coil.
The other three wire connectors were clean as a whistle, so I view all this as additional evidence that the issue is arcing, not chemical corrosion.
BTW, George M. tells me that it's almost always the cylinder #3 coil connector that fails first - the one nearest the (US) driver - so if you want to do a quick check on the condition of your coil, check that one for the dreaded black spot and dust.
