My background regarding anything to an engine is very rudementary except for a lot of reading. Anyway I was working on the timing on my 350sb and found that when setting the timing to sixteen degrees btdc initial the timing was jumping around between 14-18 at idle. After I set the timing I went to see how it throttled and when I pressed on the gas first it hesitated the began to stutter like it was about to stall. After that it picked up a little and then all of a sudden fire shot out of the carb and the engine stalled. Due to my lack of expierence in these things I am not sure what was happening. I know that the engine has a few performance parts along with a holley carb. Not sure what size but I did get the numbers 1950-5, 1633, and 10884. Thanks for any help

Definately a timing issue. When you say the timing is wandering at idle makes me believe you might have a timing chain issue (stretched). You can check this by pulling the distributor cap, and hand crank the engine slowly with a breaker bar and socket on the crank/balancer pulley on the bottom. Watch the rotor on the distributor. It should pretty much turn in proportion with the turning of the crankshaft (a very slight delay should be OK). If you notice that you can get a noticeable turn on the engine BEFORE the rotor ever moves, I'd say the timing chain is stretched to the point on not keeping accurate "time". You may have to crank back and forth to see a difference. It can still be connected and functional but stretched to the point of giving you those symptoms. I would start there.

Thank you for the reply. I will give it a try. I also wanted to update that I saw something strange. I dropped my wrench on the ground and when I picked it up I noticed that the exaust was really black and thick on the left side(looking at it from the rear) and the other side had nothing. I followed up the exaust looking for a leak in case I was missing something and didn't see anything on the right anywhere. Any reasons for this? Thanks again MMurphy77.

Make sure your firing order is correct...1-8-4-3-6-5-7-2. Put your timing light on each wire to make sure you have a good spark. Is your dizzy in good shape? points or HEI? I would pull the dizzy and make sure its in good shape. Inspect the gear on it.

I'm thinking that when you advanced the timing, you may have started the mechanical advance curve - it may be coming in and out. When advancing timing you need to lower the idle speed.

Could be a worn timing chain too, although I've never seen a motor backfire b/c of it.