can someone tell me how to install 2 msd boxes on my 84 12a so that i can have the rev limiter (i heard u need one for leading and one for trailing in order to get rev limiter to work right)
dont know much about rotary so simple explanation would be appreciated

 

Simple (and cheaper) rev limiter is to slightly lift your right foot off the accelerator pedal...

- David

 

Im interested in some MSD mods as well. Isnt this the right way of asking??? Sarcasm is not appreciated!

 

Sorry, I couldn't help myself

Check the 1st gen faq page- there is a link to MSD6A ignition thread.

- David

 

BTW, if you're interested in ignition improvements, also read the DLIDFIS faq, and search on DLIDFIS threads. Much cheaper than MSD boxes with similar improvements, but, of course, would not have rev limiting capability.

- David

 

MSD should connect to leading and trailing the same. The only difference being which pickup and coil are connected...

As far as the effectiveness of this mod, I think it'd be best coupled with a dual output coil and run a direct leading ignition setup. (Or two coils would work too.)

Then move the trailing wires to the leading side of the distributor cap and leave the trailing side of the cap unused.

HOWEVER, I've heard that the MSD is not the ideal device to be used with rotary. Might wanna look into CraneCams and/or Jacobs...

 

I thought the MSD boxes were kind of like igniters on steroids...

Ths MSD faq only shows it being hooked up to leading ignition.

Based on what people have said in various posts, seems like concensus is why do anything with trailing ignition since it contribues so little to engine output... That's the reason when I did DLIDFIS I left trailing ignition alone.

- David

 

Wire the trailing exactly like the leading except use the other ignitor leads on the dizzy. Also, on the trailing, you cannot use direct fire (long story short, it just wont work.)

 

thanks for the help

 

Thank you for pointing in the right direction. Sorry for being a douch!

 

Post some pics and a write-up when you get your mods done.

Good luck!
- David

 

For the MSD boxes to work right and not make the trailing directfire, I believe you need 3 MSD boxes. 1 for leading direct fire, and one to trigger each fire of the 2 trailing plugs individually.

 

That may be the reason the FAQ only talkes about using MSD on the leading ignition. Two MSD boxes for trailing is a lot of money for marginal gain...

- David

 

Yeah, and according to the thread starter this is only to have a "rev limiter". I'd say this is hardly the kind of use for so much money. A good rev limiter is a shift light or the stock buzzer, just lift your right foot off the go pedal when either of these goes off.

 

No, you do NOT need three boxes. I have read just about every thread dealing with the MSD boxes. Not one person has reported any problems with 2 boxes. They do however report problems if you wire the trailing to Direct Fire. Keep the trailing running through the dizzy and you will be fine.

 

This doesn't work well for using the MSD boxes as a rev limiter. You HAVE to cut both leading and trailing to limit the engine, and to do this properly you need 3 boxes. 1 to fire the leading, 2 to individually fire the trailing.

 

you only need three boxes if you run a 2nd or 3rd gen with the wasted spark,since it is a distributor you only need 2, one for lead and one for trail, my setup i use 2 6al's with 2- 2step modules wired to a switch on the clutch pedal,when the clutch is engaged the low side of the 2 step is activated,when clutch is released,the high side is activated,on the low side i use a 9800 rpm pill on the lead and 9600 on the trail,on the high side i run 11,000 on the lead and 10,800 on the trail,you don't want the trail spark to overrun the lead so i cut it a couple hundred rpm sooner.hope that helps.

 

Where can i find the wiring diagram for the MSD6A.

 

MSD ignition.com