Plug gaps for MSD systems
Thread Starter
Drifting
Joined: Jul 2006
Posts: 1,871
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From: Sault Ste. Marie Ontario
Plug gaps for MSD systems
Can anyone make a recommendation on the size of plug gap with this system.
I have the MSD's 6AL ignition module with their tach drive distributor and blaster 2 coil.
This is installed on my 454 running 9.5 CR with Edelbrock performer heads.
Currently I have the plugs gapped at .035" which I believe needs to increased before firing the motor for the first time.
I've read the gap can be as high as .060". Any input of what works in real life will be greatly appreciated.
Thanks
Ian
I have the MSD's 6AL ignition module with their tach drive distributor and blaster 2 coil.
This is installed on my 454 running 9.5 CR with Edelbrock performer heads.
Currently I have the plugs gapped at .035" which I believe needs to increased before firing the motor for the first time.
I've read the gap can be as high as .060". Any input of what works in real life will be greatly appreciated.
Thanks
Ian
Safety Car
Joined: Jan 2003
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From: Obscurity's Armpit
To the OP: Just to cover the bases, I'd recommend doing a search of C3Performance for other threads like this. In one of them, Lars gave a great explanation as to why this big of a gap may not be as beneficial as you'd think, and might actually be detrimental. 
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Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
There's no free lunch. Your coil will put out a set amount of energy. This is roughly gap voltage x secondary current x time. If you increase the spark gap, you increase the voltage requirements to jump that gap. This reduces the amount of time that the spark is actually "lit". It would be nice to always run a large gap (more fuel molecules are lit off at the start of ignition), but there's also downsides with shooting your wad with one quick spark (spark getting blown out due to swirl turbulence). Keep the gap reasonable like the guys suggested above, and you should be fine.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
If the system was adequate, it would light the fuel the first spark. If the first spark doesn't light things off, then the advance for that cylinder is retarded while it waits for the second (or third) spark to occur. So, the benefit of multiple sparks is what?
Safety Car
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From: Inver Grove Minnesota
A complete burn.
The sparks don't take long. I will shoot off the sparks in the same amount of time as a normal spark from a single spark system.
The sparks don't take long. I will shoot off the sparks in the same amount of time as a normal spark from a single spark system.
Last edited by JustinD; Aug 19, 2007 at 04:31 PM.
Le Mans Master
Joined: Apr 2006
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Instead of the secondary windings of the coil multiplying 12-14 volts
with the box its multiply at least 500 volts zaps the plug very hard
and can jump a wide gap, the standard setup used a longer duration
of spark but its very weak by comparison. the box at idle speed
will strike the plugs five to six times in 20 degrees of crank rotation with very high voltage. by 3000 rpm it will strike the plug
three times in 20 degrees. even one strike higher up in rpm is still
very strong.
with the box its multiply at least 500 volts zaps the plug very hard
and can jump a wide gap, the standard setup used a longer duration
of spark but its very weak by comparison. the box at idle speed
will strike the plugs five to six times in 20 degrees of crank rotation with very high voltage. by 3000 rpm it will strike the plug
three times in 20 degrees. even one strike higher up in rpm is still
very strong.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Instead of the secondary windings of the coil multiplying 12-14 volts
with the box its multiply at least 500 volts Incorrect. I suggest you read about how an inductive system works. Both systems (Inductive and CD) can apply 200 -500 volts across the primary windings. zaps the plug very hard
and can jump a wide gap, The HEI will fire a production .060 gap. Why the need to go wider? the standard setup used a longer duration
of spark but its very weak by comparison. And your engineering data to back this up comes from where? Gap voltage times gap current times a "longer duration" results in a higher energy spark, not a "weak by comparison" spark.the box at idle speed
will strike the plugs five to six times in 20 degrees of crank rotation with very high voltage. There is no, I repeat, no difference in gap voltage between a CD system and an inductive system. by 3000 rpm it will strike the plug
three times in 20 degrees. And 20 degree retarded spark does what? even one strike higher up in rpm is still
very strong.
with the box its multiply at least 500 volts Incorrect. I suggest you read about how an inductive system works. Both systems (Inductive and CD) can apply 200 -500 volts across the primary windings. zaps the plug very hard
and can jump a wide gap, The HEI will fire a production .060 gap. Why the need to go wider? the standard setup used a longer duration
of spark but its very weak by comparison. And your engineering data to back this up comes from where? Gap voltage times gap current times a "longer duration" results in a higher energy spark, not a "weak by comparison" spark.the box at idle speed
will strike the plugs five to six times in 20 degrees of crank rotation with very high voltage. There is no, I repeat, no difference in gap voltage between a CD system and an inductive system. by 3000 rpm it will strike the plug
three times in 20 degrees. And 20 degree retarded spark does what? even one strike higher up in rpm is still
very strong.
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Safety Car
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From: Inver Grove Minnesota
Somebody woke up on the wrong side of the bed today.
From MSD's site:
MSD 6A, PN 6200
The MSD 6A is the base model of the capacitive discharge multiple spark 6 Series design. Whether you have a powerful street machine, hard working truck or trick street rod, the powerful multiple sparks of the MSD 6A will ensure complete combustion. Benefits such as quicker ET’s, easier starting, reduced plug fouling, more power and even increased fuel economy can be expected with the 6A’s high energy multiple sparks.
Like all of the MSD 6 Series Ignitions, the 6A will work with virtually any vehicle as long as it has a 12-18 volt electrical system. It can be triggered using breaker points, a magnetic pickup or the output of an electronic amplifier. All necessary parts and wiring instructions are included.
From MSD's site:
MSD 6A, PN 6200
The MSD 6A is the base model of the capacitive discharge multiple spark 6 Series design. Whether you have a powerful street machine, hard working truck or trick street rod, the powerful multiple sparks of the MSD 6A will ensure complete combustion. Benefits such as quicker ET’s, easier starting, reduced plug fouling, more power and even increased fuel economy can be expected with the 6A’s high energy multiple sparks.
Like all of the MSD 6 Series Ignitions, the 6A will work with virtually any vehicle as long as it has a 12-18 volt electrical system. It can be triggered using breaker points, a magnetic pickup or the output of an electronic amplifier. All necessary parts and wiring instructions are included.
Pro
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From: FL.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Justin,
You gave me marketing hype. I asked for engineering data. Trust me, there is a world of difference between those two items.
ps: Let's also cut the personal comments. I'm trying to have a technical discussion here. Please restrict it to that.
You gave me marketing hype. I asked for engineering data. Trust me, there is a world of difference between those two items.
ps: Let's also cut the personal comments. I'm trying to have a technical discussion here. Please restrict it to that.