MSD Timing Retard Box Help!

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nastynova
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MSD Timing Retard Box Help!

#1 Post by nastynova » Sun Oct 19, 2008 8:35 am

I think next year instead of having to pull timing manually at the crank trigger when we put the car on the spray I'm looking at the MSD Digital Retard box. My question is right now I have the system setup on the MSD RPM Activated switch and obviously the solenoids are connected to the yellow wire on the RPM Switch which is normally open and a ground path is provided upon the when it gets to the desired RPM, now when wire in the Digital Retard Box in would I tap the Retard Control wires for each stage right in to the 12 Volt wire that activates the solenoids? My next question is what about the yellow wire coming out of the Retard Box? It shows to connect that to the white wire out of the MSD but I'm running a crank trigger so I wouldn't connect it the white wire? I just want this so when I'm going to run the nitrous and when I let trans brake button go and the system is activated it's going to pull the timing at the same time. I'm lost completely!

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Re: MSD Timing Retard Box Help!

#2 Post by John_Heard » Sun Oct 19, 2008 8:41 am

Let's back up a bit here. On your MSD RPM Activated switch you have the ground from your solenoids connected to it? That's way too much current for the RPM switch. You need to hook your relay for the solenoids to ground through the switch for example http://www.dragstuff.com/techarticles/i ... agram1.jpg

What is the PN for the MSD Retard Box you're referring to?

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nastynova
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Re: MSD Timing Retard Box Help!

#3 Post by nastynova » Sun Oct 19, 2008 9:16 am

WOW! I'm really confused after look at that diagram... :shock: The Nitrous on my car is hooked up like this:
I have the main arming switch to power the 12V wire to the microswitch on the carb and from there it goes to the Solenoids, the ground wire from the noids goes to the RPM Activated Switch yellow wire which is normally open to ground until the RPM gets to where ever I have it set at. It's basically setup so when I'm on the 2 Step I can have the pedal to the floor and with the arming switch on there are 12 volts present at the microswitch and to the noids and then when I let the t-brake go it flashes up to to the desired RPM and provides a ground path and then the solenoids are active and at the end of the run when you let off the pedal the 12 Volts are removed from the microswitch and noids deactivating the whole system. We've never run a relay on the system and luckily we've never ran in to an issue. The box I'm looking at is the MSD-8970

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Re: MSD Timing Retard Box Help!

#4 Post by John_Heard » Sun Oct 19, 2008 9:27 pm

If you're grounding the solenoids through the RPM Switch it's a miracle you haven't smoked it yet. That RPM Activated Switch, if it's PN 8956 is only good for 1.5 amps. The solenoids you have use a LOT more current than the box is rated for I'm sure.

On the retard box, it goes between the crank trigger and your ignition box, basically it intercepts the signal from the crank trigger. Crank trigger plugs into the 8970 box and the yellow wire from the retard box goes to the White wire (ignition trigger wire) on your Ignition box. There are some diagrams in the instructions... or on the MSD site.

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Re: MSD Timing Retard Box Help!

#5 Post by nastynova » Sun Oct 19, 2008 9:34 pm

hell we've always ran them like this for years and never any issues, that's why I was suprised when ya posted that. I guess I'll have to throw in a few relays then for good measure, could I just use just one 30 or 40AMP relay in place of two of them?

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Re: MSD Timing Retard Box Help!

#6 Post by John_Heard » Mon Oct 20, 2008 5:40 am

In that diagram the relay on the left is for the trans brake interupt, the one on the right is for the Solenoids. If you're not using a trans brake then you wouldn't need the one on the left.

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