ok replaced the ign switch on column checked starter found broken wire fixed that , 12 volts at coil but when I spin it over drops to 6.9 volts what's up with that? the wireI fixed goes from starter cable to alternator, the other wire from starter goes for solenoid.. why does it drop its supposse to get 12 when starting. I wonder if the guy I got it from mechanic did something wrong when he changed it to electronic ign.

Your post doesn't mention if your starting problem is cold start, hot start or both. Pontiac's are known for heat soak related hot start issues. I am fighting that battle with my own 455. I have replaced the battery cables with 0 gauge wire. I have a DEI starter heat wrap and I am about to upgrade to a mini-torgue starter.

If I had to guess, the problem is most likely one of four things.

1. Bad/weak battery

2. Bad/weak engine ground(s)

3. Excessive starter resistance

4. Bad coil and/or ignition/distributor

You mention that voltage drops to 6.9 volts, that is too low to start most engines. Anything below 9 volts is questionable.

Start with your battery. Take it to a store that can do a load test. If your battery is old (3 or more years old), you may have internal cells failing. The battery may show 12V but due to bad cells, you may have lost a lot of cold cranking amps (CCA). A load test will see if you battery is still strong enough to turn over the engine.

Check your battery cables and make sure they are clean and not corroded. Ditto with the contacts on the starter and engine grounds. Corrosion causes heat and leads to voltage drop. Also make sure your engine is properly grounded to the body or frame.

Lastly your ignition system may be going bad, including the distributor (HEI or points) and coil (if you have an external one).

Edited 3 hours ago3 hr by Frosty

battery is good spins over great when I stop cranking it goes to start, I'll check gronds but think its something different, still trying to figure it out