To correctly install a push button starter, Bring a wire 10 Gauge wire from the Battery post on the starter Via a fuse link to the area you want to install the pushbutton.
BE SURE the contact rating on the button is capable of supporting the draw of the solenoid, (about 50 amps) If not, your contacts will melt after a few uses, and you could have a fire..If the contacts ARE under rated, you MUST install a relay.
From the other side of the push button, run a 10 gauge wire to the wire coming to the Ignition switch that is hot in Start only. Parallel this wire here..DO NOT go directly to the "S" on the solenoid..this bypasses the neutral safety switch and is dangerous..the neighbor kid playing in your rod could find it start it in gear and ram it through your house in a New York Heart beat..
That wire can be found at the bottom of the steering column..With a DVOM , set to DCV, set for DC X 50 , probe the connector..It will be the ONLY wire with power when the key is held in "Start" (pull the "S" wire from the solenoid while testing so you not constantly cranking...)
For the Ignition..unles you have a switch that has a contact rating of 40 amps or higher, you WILL need a relay..Most folks believe a coil only pulls a few amps..a Common misconception..a Stock coil pulls 20 to 30 Amps..a performer pulls 30 to 45 amps..a plastic toggle , with a 5 amp contact will melt and cause a fire..
To hook up a relay, bring in any source of 12 volts , unswitched, Fuse it at 1 amp..run that to your toggle switch. the other side of the toggle will run to the RELAY COIL, #85..RELAY COIL #86 will get a hard , properly bonded ground. RELAY CONTACT #87 gets a 10 gauge wire that will run to the starter battery post, at the solenoid..via a proper fuse link. RELAY CONTACT # 30 gets a 10 gauge wire that will run to and Parallel with the HEI BATT wire.. that's it..
Another good little system, is using the relay without the toggle..hook the coil to your CD player power antenna wire and ground, and the contacts will run BETWEEN the HEI BATT wire (Cut and add each contact to each side) ..In this configuration, the ignition will only have power when the Face plate is installed AND the unit is on..The only drawback is the Radio must be on at all times while you are driving..use mute if you don't want to hear it..
When you leave..take the faceplate, the radio and relay can not activate, and the car has no coil power and won't start. a thief will move on..