Not the way I would do it, but that does not make it wrong. I like things, especially wiring, very simple. That said, I would wire my relays, with 12v to post 30 and out to the solenoids from post 87. This makes the relays hot all the time, with clean power. You wire the ARM switch, to put power to the WOT switch. The WOT switch, then triggers post 85 on relay 1 and can also trigger the timer, that turns on relay 2. The timing retards can either tie into the outputs from the relays, post 87, or can tie into the trigger, which is post 85. Ground post 86 on the relays. You can also tie the "hot" to the purge button, onto the arm switch. This way, if the purge won't work, you know you are not armed. I personally never use hobbs switches, never seen the purpose of one, plus they tend to cause problems with surging systems.

Monte

Thanks... I will pass this info on to him... its the
guy you meet on drag week with the 52 ford PU...
he's still trying to break stuff

Some timers can be used in place of a relay. Such as an ARC unit.

I monitered my nitrous activation through the retard on the 7531 so I had data as to whether the hobbs ever caused any issues. Running 25PSI to the regulator and having a hobbs switch set at only 7psi installed in that part of the fuel system you will never see any blips on the hobbs. It is when people installed them according to NOS directions on the low side with only 5.5psi in the tuneup you have issues. I tried this and even at 2psi on the hobbs switch it would blip the activation circuit. This is when Steve Johnson and Richard Omally both explained to me that it needed to be on the high side if I wanted to use one. Never had an issue sense. In fact I had a fuel pump take a dive just before staging. The nitrous wouldn't work. I was pissed to say the least until I saw the fuel pressure gauge and got the car out of the way while there was some hint of fuel in the float bowls.

Monte you make a good point on the wiring of the relays. You would never want to run solenoid current through a microwsitch. Switches when failing can do two things stick closed or open. Nitrous activation is not a good place for a stock switch. Be very careful when purchasing these relays. Some are absolute junk. The ones that advertise 40A ratings are pretty good. You are better off to go to a junkyard and get relays out of the fuse box under the hood of a late model car. Most I have seen are a lot heavier built.