Ignition Box Questions

[Mark Eaton]

I could use some advice regarding these Multi spark capacitive discharge ignition systems (CDI). First of all, are they really necessary? I know, sounds like a stupid question, I mean after all they appear to be ubiquitous in these build threads. I don’t want to sound like a heretic or anything but I’m just asking the question so that I can learn more. From what I’ve read it appears they help in cold cranking ability and to maintain the spark at a higher RPM. They also look really cool in the engine compartment.:cool:

I will be running a Dart 347 engine (377 HP) with EFI (Holly Sniper) which came with a stand alone coil ignition. I have been looking at the MSD products, their six series appear to be what I need. I like the idea of the rev limiter. Does that mean I can turn rev down so low that my teenage kids can’t drive it more than about 20 mph? I still have several years before that day will come, however, I need to plan in advance. According to the Holley website the Sniper EFI has programable rev limiting capabilities. Maybe that would eliminate my need for that on the CDI system?

I appreciate any advice.

Mark

[Joee]

Necessary no, if you are trying to get every bit of high rpm performance out of you motor then yes. If you have an adequate rev limiter built into the system you have then you should be good to go. The best way to limit teenagers is No you cant drive it without me in the car. With your power you might not want anyone driving your car without you in it.

[NAZ]

I run an MSD CD ignition but no you don't have to run one and I suspect the prevailing opinion here will be not to run one.

[bobl]

No you do not need an ignition box. You can control the rev limiter with the EFI, so you don't even need that feature. The multi spark only works at lower rpm, usually below 3000 rpm so any benefit is at idle and low speed drivability, if the engine needed some help to begin with. A mild street engine that is EFI should run fine without it. You could also go with a high performance coil if you wanted to get a stronger spark. Something else to consider, an ignition box is another possible failure point.

Bob

[Jeff Kleiner]

Am I going to have to give my "Don't try to run race car parts on a street car" speech again? ;)

Jeff

[phileas_fogg]

If you choose to use the MSD box be sure to pay close attention the Holley installation instructions; the MSD box can destroy the Holley computer if not installed correctly. Also, if you go from a standard coil to the MSD box or vice versa you'll have to change the wiring a little bit. The wiring changes are not hard or complicated, just not a "remove & replace" operation.

Cheers,


John

[Itchief]

You could use the MSD ready to run without a control box unless you want to do timing control

Rick

[CraigS]

No you don't. A plain coil w/ a ballast resistor and the correct distributor is all you need.

[Derald Rice]

I like the idea of the rev limiter. Does that mean I can turn rev down so low that my teenage kids can’t drive it more than about 20 mph? I still have several years before that day will come, however, I need to plan in advance.
I appreciate any advice.

Mark

Your insurance may answer the question about a teenager. With Midwest Classic Insurance (which a lot of us have), any occasional driver is insured to drive the car if they have 10 years driving experience. The requirement of 10 years driving experience disqualifies teenagers.

[first time builder]

You will find many horror stories about MSD 6AL me included, The only box I have used without problems is the MSD StreetFire. It doesnt have as many Bells and whistles but does the job.

[Mark Eaton]

You could use the MSD ready to run without a control box unless you want to do timing control

Rick

Thanks Rick but I'm a little confused by your response. Could you elaborate?

[Itchief]

You can run the msd ready to run distributor bye it’s self without any control box and just have the capacitive multi spark as a stand-alone distributor

That’s what I am running

I’m sure there are some other vendors that offer a similar distributor

[MPTech]

Just curious about your numbers, wouldn't a 347 Dart make well North of 377hp? (why would you need a Dart block for 377?)

[Joee]

Just curious about your numbers, wouldn't a 347 Dart make well North of 377hp? (why would you need a Dart block for 377?)

Maybe RWHP ??

[Itchief]

Mark

Sorry I miss read your question

I would keep the ignition that came with the motor and use the efi to limit the revs

I found that with the MSD atomic efi the rev limit is not a soft limit it cuts the fuel off once you hit the limit and then turns it back on once the rpm drops so it becomes a set of pulses

Rick

[Mark Eaton]

Just curious about your numbers, wouldn't a 347 Dart make well North of 377hp? (why would you need a Dart block for 377?)

It is a Dart 347 SHP from Forte. It dyno tested at 377 hp @6250 RPM and 389 ft/lb torque at 4200 RPM. At least that's what it said on the information they sent me. Does that not sound correct?

[Mark Eaton]

Mark

Sorry I miss read your question

I would keep the ignition that came with the motor and use the efi to limit the revs

I found that with the MSD atomic efi the rev limit is not a soft limit it cuts the fuel off once you hit the limit and then turns it back on once the rpm drops so it becomes a set of pulses

Rick

Thanks Rick,

That's what I'll do. Sounds simpler, less parts to malfunction.

[Mark Eaton]

Am I going to have to give my "Don't try to run race car parts on a street car" speech again? ;)

Jeff


Jeff,

I probably need the lecture again. But I'm a little surprised to hear it from a fellow Hoosier. I am IU alumni. :o

Mark

[CraigS]

Google "MSD 6AL" and see all the failures. I wouldn't install one if it were given to me. And that is based only on this and the other forum. I have no idea the failure rate on all other cars.

[TexasAviator]

I made 475 HP on the dyno with the fitech efi, coil, and a distributor. Msd is snake oil that sells well. However, if you need it for a carbed or non cdi setup its good, not great. The muscle car guys believe heavily in them and it has just been perpetuated for decades as a power mod. Sad thing is its worthless on an efi car since it already has built in control.

[bobl]

It is a Dart 347 SHP from Forte. It dyno tested at 377 hp @6250 RPM and 389 ft/lb torque at 4200 RPM. At least that's what it said on the information they sent me. Does that not sound correct?

Those numbers don't add up. I'm guessing the info they sent with the engine is wrong. You would not expect to see an engine that makes peak HP at 6250 rpm to make peak tq at 4200. I'd call Forte and ask about it just for peace of mind. Did they send a dyno print out or just a statement of the numbers?

[TexasAviator]

listen to bobl, he's dyno'd a lot of engines, including mine. Those numbers are way off. Good luck.