CJ7 backfiring and won’t start now

I have an 81 cj7 that backfires really bad on start up. I timed it with a timing light yesterday to 8 degrees since I just put an hei on it. I timed it and drove it for about 5 minutes then turned it off, and when I went to turn it back on it wouldn’t start unless I had the gas pedal to the floor and it would just backfire like crazy. I also have a new cheaper Carter carb. One time, before I timed it, it was just very hard to start and wouldn’t stay idling until after about 3 minutes of me keeping it alive, but ran fine after. Now it won’t start at all unless I have the gas pedal to the floor and it just backfires. I turned it to TDC by hand and took the cap off the distributor and it looked to be in the spot it’s supposed to be in. Plus it wasn’t very hard to turn it by hand so I don’t think it jumped on the timing chain, but idk. I’ve read a bunch of posts but couldn’t find anything quite like my situation. I need some help

 

Remove and plug the vacuum advance tube and time back to +-1 deg. If the backfiring stops, you might want to look at the Carter carb. You should also preform a compression test. The rings and bearings on the 42 year old 258 are more likely a figment of the imagination by now.