Help with ignition. Mag or MSD?

[DansBlown73Nordic]

I just bought this 454 blower motor. It has a Mercruiser HEI. Ignition. Im sure im not going to use this set-up. I have had way to many friends have these things break for know reason.
I have wanted to try a mag. because I think they look kinda cool. I know the mag. is kinda old school. Does anybody have any input on what is really better? This will just be a Cruiser type Flatty. It will never be raced or anything, well maybe a couple drag races. :D

[Rexone]

Mags work great with the following areas of exception...
They have a weak spark at low RPM inherent to the design. What that means is loading up during extended periods of idle if your mixture is at all rich, fouled plugs, etc. (I've been through this with my turbo motor). Ok for race boats. Not ideal for extended idle situations like marinas and stuff.
They also use a little horsepower to turn them since they are a generator. I forget the number but it's negligible.
Once in a while the magnets have to be recharged. But other systems have issues occasionally too so I don't view that as a liability only on a mag.
Unless I had a used one I wouldn't go that direction spending the money from scratch. I'd put an MSD distributor with a Crane Marine 6 box and forget it. Lots of reliable voltage potential, clean idle, rev limit built in, bitchin distributor.
Just my .02

[Moneypitt]

How can a mag make less voltage at lower RPMs?? I was told years ago that the main advantage to a "real mag", (no external parts) was the constant 24K spark voltage. At idle, and at 10,000 RPM the output is the same. Just gap the plugs @ .018, and you're done... Any input on this subject ??...........Moneypit

[ACCEPTENCE]

It's my understanding that a mag produces less spark value at an idle as well.
I was at Zig's shop years ago haveing my mag done. He set the mag in the bench tester. connected all the wires and fired it up.
At 1000 rpm's it would only jump a spark gap about an inch or two.
At 8000 rpm's he opened the spark gap thingy and that spark was flyin about six inches across the gap.
Pretty amazing tester unit he's got!!!
Take from this what you will but I'm thinkin for a cruiser application the MSD deal would be the way to go.
my .02 worth:D

[Infomaniac]

Mag is good if you have manual gauges and no alternator. Battery lasts all weekend.
The external coils have increased the idle speed spark of a mag quite a bit.
If you know how a mag works it is easily uderstandable. RPM's increase the current. A mag makes alternating current.
The permanent magnets rotating away from the laminated soft iron primary coil core cuases the magnetic field to collapse. The points and condenser help with this.
One of the variables that determine how much energy is produced is the speed of the magnetic field collapse. An increase in RPM's increases the field collapse.
You can hook up a multimeter to a piece of small wire. Rapidly move a strong magnet back and forth over the wire. You will see the current generated. Similar principal.

[Fiat48]

We did some track testing with an unblown alcohol carbed 468 chevy. Fresh Vertex mag and made run #1. Then changed the entire ignition to Mallory with Highfire box and made a run. Then came back in and ran with MSD distributor and MSD 7AL.
The results no difference in speeds or ET's. But starting with both electronic systems was near instant and the idle was much cleaner. The vertex was hard as hell to start when the motor was cold. Just some worthless information.:)

[78Eliminator]

Actually, I am glad this post came up. I had been wondering what the deal was with mags and why people run them. I was wondering if there was any reason besides the fact that you can run without an alternator......

[Fiat48]

I run super mag 3's because I've never had a failure and skert of the fact that a spark box malfunction can mean blower in my lap or lake or whatever. :D

[Infomaniac]

Keeps the spectators happy.

[DansBlown73Nordic]

I had found a couple good deals on Mags. They were both around $250. I think I will just spend the money on a MSD. I do not want to have to screw with fouled spark plugs.:yuk:

[blown540flattie]

My 2 cents----> A mag is the only way to go.http://www.***boat.com/image_center/data/505/1004IM000702-med.JPG