Timing Woes

Heres the whole story. 2 springs ago I accidentally turned the oem distributor, nut was loose. So I got it back to where it would start again. The next week it would not start again. Moved the distributor to where it would start again, it had not moved! Seems like the position it would start on was changing! So I got a friend to help me time it perfectly. Got it started, with timing light got it perfectly timed and running perfect. After day or so would not start again!!!

I had a Pertronix old points replacement unit in the original distributor. Hoping that had gone bad I decided to order these.
I installed a MSD 8578 distributor and 6A control box, new coil. The light on the box is blinking, timing light showing spark on the plug wires. I made sure the distributor rotor is pointing to cylinder 1 at TDC. And I did a lot of trouble shooting to make sure everything is installed correctly. So it seems the original timing problem is still the cause.

There have been no changes from the time it would start all the time. Only drove on weekends. The timing chain/set is barely used. There is no sputtering at all and not all the valves rockers can be off. Besides starting to just take the engine apart looking for problems any ideas what I can do? Thanks.

No it will tighten down so that the distributor wont move. It is always tight when I try to start it.

I was definitely right about the hold down was fine. It turned out I didn't realize that I could have set it to TDC on the exhaust stroke which was the case. So used the finger over the #1 plug hole method for the first time. bumped engine till air pushed out. Turned 12 degrees BTDC and bingo! Got some firing. So now i gotta do a carb kit and blow the bad gas out cause it wont idle. And the fuel pump sounds like a box full of rocks!