Engine won't start after a few upgrades

Hello All!
I am working on my 70 Eliminator, Boss 302. I parked it last fall with a list of “winter upgrades” to accomplish before Spring. Pull the dash and cluster to replace a few burned instrument cluster bulbs, send the 8k tach out for a rebuild/retrofit, replace dual points with Pertronix II ignition and coil. I’ve reinstalled the instrument cluster and noticed the fuel gauge does not move now. Parked it with about 3/8. It worked perfectly before (had the sender rebuilt by Bill Basore with new float) and has worked perfectly. I added 6 more gallons of fuel to see if “stirring” the tank would help. It did not.

The tach is now VDO conversion, 3 wire with a hot wire to the fuse box, ground wire and a wire to the negative side of the coil. I’ve installed a jumper wire where the OE tach plugged into the factory harness. Engine cranks, won’t start. I have 12.4 volts to the positive side of the coil thru the factory wiring harness (key on, but not cranking it) as the Pertronix II requires 12 volts. I’ve rechecked TDC ( I did pull the distributor to fully check spring operation, etc) and it is good. With the timing light installed, it flashes when cranking the engine.

I sprayed a shot of ether in the carb to try to get it going. Engine only cranked. I’m missing something, but I don’t know what. Any and all ideas would be greatly appreciated. Thanks!! Kenny Bailey

Start with the 3 basics, Fire, Fuel, Air.
Make sure you have spark at the plugs, Screwdriver in the boot, hold it close to the manifold look for the spark!

Make sure Fuel is making it to the carb,

Make sure the rats haven’t built a nest out of your air filter…

The quickest easiest thing to check is to hot wire it. Run a test lead (aligator clip lead) from the battery post of the starter solenoid to the posititve post of the battery. If it starts and runs then the problem is the ignition.

Ummm…something got lost here in typing. There should already be a cable from the positive post of the battery to the battery post of the starter solenoid.

I think Bill meant a wire jumping from the + post of the battery to the + post of the coil.

Thanks Royce!

Well, I’ve sorted out 95% of it. The wiring harness to the instrument cluster wasn’t fully snapped in place. Felt the “click”, fuel gauge is back. Timing was a mile off. Visually, the rotor was pointing to the right area (engine off) at TDC, but could not advance the distributor far enough to see the timing mark. Repositioned, timed, running. Now, the tach, which was converted to a 3 wire set-up, is not working. I’ll make a call on that later.

Thanks for the input! Kenny

With the tach, there is a glitch that not everyone known about.

You need to run the power and ground wires that are part of the OEM wiring harness through the tach or connect them together so that they complete the ignition circuit. In fact, when OEM tachs fail, the car won’t start. These are located behind the instrument cluster. In standard cougars, these are hooked together.

Some people leave them like that and wire up the tach the usual way.