What do they really do and why would I need one? I have ordered a new ac delco opti since my 2nd new accel died after 4 mos. I am upgrading my ignition system and I see on here quite a few people have these but i havent really looked at what they do. Just thought i would ask a question. Thanks

 

MSD's website best describes what they do.

 

The brand name pretty much sums it up too, Multiple Spark Discharge.

I like mine. Didn't really feel a difference, except at higher RPMs. But it's nice to know it's there if I ever heavily modify the engine (which is inevitable), plus the 6AL has a built in rev limiter, and you can wire a killswitch to it if you want.

 

On a stock or stock-ish car I doubt there is any advantage. OTOH, cars with significant mods NEED a stronger spark. Basically, a CD ignition box increases the available current to make a spark. It takes more energy to make a spark under high pressure.

Rich

 

Thanks

 

In my experience with an MSD 6A box on my car, which is stock for the most part actually ate my opti for lunch in about 18 months (car was a DD then). When the opti was opened up, the contacts were disintigrating, turning to carbon dust.....remember the MSD box gives you four plug fires per cycle instead of 1 so its like 4 times the wear on the electrical (ie opti, plugs etc) downstream of it.

I have since removed it....been about 5 years and its been perfect.

Just my $0.02 though....

 

Good point. I have also seen decreased Opti life with a CD ignition box.

Rich

 

DD with 8+ years on my opti with an MSD 6A and no troubles contradicts what you say. I had the cap and rotor opened up after quite a few miles with the 6A and noticed no evidence of abnormal wear.

 

Ive search about MSD's boxes eating opti's and found plenty. I dont really know what and who to believe. Mainly because there are lots who say their box deastroyed their opti.
I am looking a getting a mallory box because they are so popular for our cars. They also have a rev limiter and window switch and can use a MSD part for a plug and play install.

So in short, do you guys think opti's dying are related to ignition boxes?
Or maybe a few guys just had some bad luck?

 

Interesting....I'm glad yours is holding together.

 

Again, I would like to thank you guys for your responses. BTW I havent been stock for a little while now. My sig does not say it all. Everything won't fit.

 

Previous posts have suggested the motor idles smoother with it.It has been known to blow opti's right off the face of the earth,but I dunno,I sell furniture.(Beer time.

 

Could be that those people had opti troubles and thought slapping a box on there would fix it. Then the opti died. You never know the scenario. I'll bet there are a lot more people out there with ignition boxes and optis not having troubles than there are having troubles. I couldn't be running one for 8+ years if it ate optis like people say.

 

I was running a MSD 6A from about 50,000 miles to 109,000 miles when the stock opti finally crapped out. I personally doubt its the ignition boxes.

 

Just to report my experience with MSDs.

I have run the same MSD 6a box on my 90 454SS truck for 12 years and over 105k miles. Cap and rotor on the ign system showed no abnormal wear IMHO. Sure, I replaced these parts over time but nothing unusual to report. Just normal wear. I tend to replace ign parts before they have lived a full life anyway.

The MSD Dig6 on my LT1 has been there for 11 years. My stock opti died from a bad bearing at 15k miles. An OEM replaced it for 30k miles without incident. The Dynaspark unit has been on for the last 10k miles. It crapped out for unknown causes and after rebuild has been going well for the last 2k miles.

I can't say that the MSD has caused any problems for me. But my experinece doesn't necessarily prove that MSD don't shorten the live of an opti either.