backfire at idle after car sat

[bandit]

Was working on my bodywork for the past two months so the car didn't really move during that time. Went to take it to the painters on Monday and the thing would not stay running on it's own at idle and backfires like crazy when I tap the pedal to try and keep it running. Finally got it to limp down the road to the painters after letting it warm up for a bit but could not go more than half pedal or it would start bogging down and backfiring. My first thought was plugged air filter from all my sanding but took it off and no improvement. Ended up having to retard the timing and seems to have helped but do not know why this happened. The car was running fine before I started the bodywork and nothing mechanical was touched during that time.

Why would my timing be off from sitting? Or could this be another problem and retarding the timing is just compensating for it? Need some thoughts on this. I am at a loss

 

[Plucked Chicken]

Could be wet distributor cap - could be timing chain - could be striped distributor gear - Just had this '70 472ci Cadillac running fine - next minute back fired and acted like a jumped timing chain - here's how she looked inside due to lack of oiling issue....... Distributor gear jumped a cog from wear.......

 

[bandit]

Thanks Chicken. Had distributor out earlier this year and looked fine so doubting it is that unless something happened in that time. I had same thought on wet distributor cap but looks fine.

Could my gas have lost enough octane in two months to make it run this bad?? I wouldn't think so but so odd how it was running fine then not and only difference is two months of sitting. I run a mix of racing fuel and normal to get it to around 96. This higher octane lets me advance it a little. Starting to wonder if my gas lost enough octane to where it hated being advanced.

 

[eldubb440]

possible vacuum leak........dry rotted rubber......... happened to me just recently

 

[bigblock]

Ethanol has your intake valves sticking open occasionally.

 

[bandit]

I'll have to check for vacuum leaks around the intake and carb tomorrow. Lines are fairly new so doubt they are suspect but will check them as well.

I drive up north to get ethanol free gas. Not sure about the racing fuel though. Mix in about 3 gallons on fill-ups.

 

[bandit]

I figured it out. Went out today to start it again to check for vacuum leaks and the backfiring was back and it was running like crap. After it stalled a few times it was hard to turn over(dying battery) so got me tracking the charging system wiring around. Ends up the plug to the voltage regulator was on but loose. Pushed it back on tight and the car is running great again.

If anyone runs into mysterious backfire issues out of the blue, check your voltage regulator and the plug.

Hopefully all that backfiring the past two days didn't screw anything up. We'll see......