MSD setup/wiring verification please

[dustbull70]

Hello everyone, Im at the stage of trying to figure out how to wire the car up. I have assembled my MS II and relay board already. I will be using my existing ignition: Mallory Hyfire 6al and Mallory unilite distributor-but of course controlling the advance/retarding by the MS. I want to make sure that I am wiring everything correctly before turning the key...
As per the MegaManual and the MSD instructions I should connect the unilites wire to TACH on the relay board (which should be pin 24). I then connect the 'MSD' box to the output S5 (which should be pin 36) correct? And S1-4 and VREF isnt used?
Then in tuner studio:
Ignition input capture-Rising edge (using optoisolator, U4 hall sensor circuit)
Crank Trigger-Trigger rise
Coil charge scheme-standard coil charge
Spark output-Going low
Max spark duration-25.5
Dwell-25.5
If i am missing anything please let me know, i cant afford to be frying up any electronics..Thanks

[dustbull70]

Sorry, just forgot to mention that i am unclear on the dwell and spark settings. Tunerstudio is telling me i cannot have a dwell greater than 8...im trying to search for why as you read this, thanks.

[kjones6039]

A dwell setting of 25.5 is HUGE! That will surely fry something!

I am not familiar with MSD but I suspect that dwell should be in the area of 3 ms or so. One of the exerts can tell you just what you will need for MSD.

That is why TS won't let you enter a dwell that large also.

Ken

[trakkies]

25 degrees is near enough the dwell on an 8 cylinder points dizzy. Could that be the confusion - TS uses milliseconds?

[Matt Cramer]

A dwell setting of 25.5 is HUGE! That will surely fry something!

I am not familiar with MSD but I suspect that dwell should be in the area of 3 ms or so. One of the exerts can tell you just what you will need for MSD.

That is why TS won't let you enter a dwell that large also.

Ken

Setting dwell and maximum spark duration to 25.5 both will give you a square wave with a 50% duty cycle like a set of points. The MSD box doesn't have a true "dwell" on its spark output as it uses a short CDI pulse.

[kjones6039]

Ah ha! Well, I learned something there.

Thanks,

[dustbull70]

Huh, thanks, that makes a bit more sense...i got the Dwell and spark set to 25.5 now. But can anyone else confirm that pin 24 goes to TACH on the relay board and pin 36 goes to S5? Also, are those the only two wires i need to connect for the MSD box and optical dist? it just seems like im missing something since the HEI directions have like 4 other wires that need to be connected....Thanks again for the help so far

[Matt Cramer]

Huh, thanks, that makes a bit more sense...i got the Dwell and spark set to 25.5 now. But can anyone else confirm that pin 24 goes to TACH on the relay board and pin 36 goes to S5? Also, are those the only two wires i need to connect for the MSD box and optical dist? it just seems like im missing something since the HEI directions have like 4 other wires that need to be connected....Thanks again for the help so far

Yes.

MSD boxes don't have a bypass mode like HEI.