I have a 1968 C3 that started life as a L71. I rebuilt the engine to use High Compression (12.25-1) and I needed a good spark. I started by rebuilding the factory Transistorized Ignition and it's distributor and then after seeing the pathetic spark I switched over to a MSD Billet Distributor with mechanical Tach drive and a MSD 6AL and another MSD Programmable Retard Box which allows me to pull 20* when cranking the Engine. When I test the spark it sounds like a welder instead of a spark. I keep my plugs gaped wide and still it burns the electrodes. This MSD system has worked GREAT for over 20 years now.

Now I am in the process of installing a Holley Sniper Stealth 4150 EFI system and it wants to control the timing of the engine as well as the fueling. The New Holley Software that came with my Sniper has the ability to make your own advance curve which I am hesitant to play with for fear of hurting my engine. I have a Snow Performance Water/Methanol injection system that will be controlled by the Sniper Software. With the water/meth injection the engine can make a lot more power and handle even more timing. I am glad the EFI has data logging built into it allowing me to monitor the interactions going on in the fuel/ignition systems.

The fact that the MSD system does the multiple spark discharge is why so many people like it. They make a brand new MSD box that plugs into many newer cars to give the new cars the MSD at low rpm's. It is designed for today's car engines. The technology is still applicable in today's Car engines and in my opinion it is still a great product!

Be Well and Stay Well!

P.S. I raced Motorcycles earlier in life and they had magnetos on them, it would really hurt when you got zapped by it. Magnetos are great as they use no external power to make them work. No battery needed...

 

I used to run a magneto in my old drag car and twisted the beast with one hand and my other was near the wrong place 😂. But I ended up with a MSD 7 That worked well. This 6 A L did exactly what I needed.

 

Had a mid-sixties sporty CH w/ OE fairbanks-morse mag ... it'd light ya up as well.

 

I can build a T/I system that will clean your clock, so don't blame it.(The Chrysler was better).
Yes, electronics have advantages. Hell, the new cars are computers.
With these cars, adding fuel injection,comp controlled ignition, crank trigger/coil packs,
Be easier to drop an LS3 and done.

 

Yes, the dual mags on totally independent circuits, i.e. not only dual mags but dual plugs per cylinder, are for safety. But a side benefit is additional power. In a typical small airplane air cooled 4 cylinder like the Lycoming 360 ci in the plane I fly, having the dual ignition adds about 4% additional RPM vs a single circuit. We know this as during the pre-take off run up we shut down one mag, check for an engine drop which tells us that the one we shut down was working at some level and that the other is running smoothly by itself. Then we turn that mag back on and shut down the other for the same check. Of course, these engines never exceed 3000 RPM, so they're always in the range where two sparks can boost power.

As for the multi-spark capacitive discharge systems, I had an old Accel unit I put on my L82 sometime in the early 2000's. The one advantage I saw was being able to advance the spark a little more without knocking. When the Accel unit died about 3 years ago I looked to Accel to cough up on their lifetime warranty. I found they were now owned by Holley. It took a little convincing but I got Holley to pony up a free MSD 6A to replace it. I have not though put it in the car to date and have no current plans to. Not due to any performance issue. It's just the thing is so big I'm not sure where I would place it.

 

Dual flame propagation. Early 20's race heads used it, along with dual magnetos.

 

Years ago, a member here named San Diego Paul had a crazy miss at idle. I went down there about a year or two after Lars hosted a Tuning for beers at his house.
His car idled VERY smoothly, but every 4 or 5 minutes it would "blip."
Paul spent hours checking/changing everything but that dam box.
I told him to change the box. He did. It went away.

Fast forward 10 years. Another member, Corvettes White had a weird miss around 3000RPM.
I hooked up a MSD test box to his ignition.
Right around 3000RPM, during transition, the spark was all over the place between multi and single, erratic as can be.
Changed the box, it went away.
We will install an Updated TI box and coil this summer. His pro billet MSD distributor will trigger a TI system just fine.

I have little faith in the "magic box."

 

Mine hasn't caused any problems. It just sits in the cupboard minding it's own business.

 

Hello there Big2Bird,

The factory TI that came on my C3 was "original" and since they are of value I removed mine after having it rebuilt by Dave Fiedler. It was rebuilt and put into a vacuum bag to keep them safe and dry. I never had any issues with my factory T.I. system but decided I wanted more spark for the higher compression engine I was building. I switched over to MSD for the multiple sparking and surviving while working on a High Compression engine. I have killed two MSD coils in the past years and that will continue MSD tells me unless I spend considerably more on one of their Blaster Coils.

I recently bought a Holley Sniper Stealth 4150 kit for my 427 in my C3. It wants to control the ignition as well as the fueling so I might be getting rid of the MSD equipment altogether. The Holley system lets you choose points on a advance curve and makes a 2D ignition table as it learns. I can go into the software and choose to build my own ignition table or I can simply import someone else's. It even has Data-logging built into it. The whole thing fits under the hood which is really amazing.

I am going to keep the MSD billet distributor as it supply's my Tach with a spinning cable like the factory T.I. did. I need to lock out the centrifugal advance and remove the vacuum advance to be able to use it with the Holley Ignition. I have been reading up on making a good advance curve for this engine of mine. I will start slowly and work my way up, currently I have 38* total at 3000 rpm and the big block seems to like it even with cast iron heads.

Be Well and Stay Well!

 

Thank you for sharing.
I am also glad you gave some insight into their shitty coils.
I have started a box of burnt/leaky ones. They are truly trash.

 

I can't count the times an HEI module left me or someone I know on the side of the road, usually when it was bitter cold or in the rain or on the capitol beltway during rush hour not being able to get off the road. Yeah the. HEI is an electronic marvel itself. Nothing is flawless.

 

Yup, HEI modules fail occasionally; but my WAG their MTBF is far greater than 6 box (or 7).
Module's quite small & cheap to keep a spare in car. Fairly easy to swap roadside ... all same for coil as well.

Good luck troubleshooting 6 box roadside (or 7) ... or remembering how to bypass.
Again, 6 box (or 7) makes for snappy kindling (fat lighter in regional parlance) ... until ...

Those CD boxes you used to see atop CUP cars' dashes prior to EFI ... they were Mandated by Nascar rules and ALL of them were were considerably reworked/beefed up (if not cheated up) by ignition pros. They're still mandated in some lower tiers. IIRC, ARCA ran Mallory. In case of failure most all tiers ran two separate, switchable boxes (no dual plug heads). I say this with certainty as I scratch-wired a Busch car entirely including brake blowers. Even then, I was too fn old to be twisting around in & out of that chassis. FWIW, here's one who'll be glad to rework yours http://www.nelsonspecialties.com/ ... be it Crane, Mallory, MSD whatever.

your car & money & time

 

I can count the number of times mine failed since new in 1980, used regularly until 2005, then sat for over a decade, and now used again, all with everything original except the cap. In those 90k miles, it never left me sitting. I will note that I swapped in an accel coil in around 2000. But I put the original one back in when I started driving it again. The Accel epoxy was cracked and its coil resistance was not up to snuff. The original coil was better.

My experience is limited to my car, but what I know is I've had the original HEI and coil for 40 years and they have never failed. probably had fewer than 5000 miles on the Accel coil and capacitive discharge system and the capacitive discharge system left me on the side of the road - fortunatley within 100' of driveway, but it uphill, and the coil I tossed given the degradation.

I'm sure both these things will fail, but I'm betting the HEI is more reliable at least with good internals, not the crap sold at AA, AZ, and the like.

 

This is more in line with my experience.
I have owned 5 GM cars with HEI ignition.
Zero failures, just usual tune ups.
3 Fords. One the points fried in the Sierras and the Lincoln had thin film ignition. What a piece of work that was.....
I did change a module in a boat. Owner let rain get to it for 2 years.

 

nelson crozier has been a friend of mine for close to 40 years. I recently posted a response to Lars about contacting him about getting his distributor machine fixed. And yes Nelson got sued by MSD for making thier boxes better.,those were analog boxes this one is digital,completely different animal.. first problem i haveit goes to mooresville..

 

Keep us posted. Knowledge is power.

 

I put a 6A box on my car back in 87 and it's been there ever since. hasn't given me a problem ever. i have wanted to get a new digital version because they have the rev limiter built in but with all the problems i've been reading about with these over the last few years i'm afraid to replace mine with a new one.

 

One huge thing about the Digital 6 is that if it quits....there is a plug on the harness......you don't have to re-wire the whole damn thing like years past.

Jebby

 

Well now i'm thinking maybe by a digital 6A and put it in and keep my old one and get a extral plug from MSD and hook the wires up to the plug so i can swap the old one back in if the new one dies.

 

You're a continued fountain of ignorance.