Timing and carb tuning

Well I've got the 73 up and running but I'm having some trouble with the fine tuning of things now. The carb is a 650 Speed Demon DP with quick fuel metering blocks, power valve delete, and is jetted 66/70 right now. The dizzy is a fully mechanical Mallory Unilite with a hyfire coil. The problem that I am having is that the engine stumbles off idle and will backfire through the carb quite frequently. I think I may have the a/f mixture going pretty well but I think the timing is coming in way too late and causing it to fire retarded (which is why I am glad the carb has the power valve delete). Looking for any input that can get this beast running properly so that it can become my daily driver.

torkair wrote:Well I've got the 73 up and running but I'm having some trouble with the fine tuning of things now. The carb is a 650 Speed Demon DP with quick fuel metering blocks, power valve delete, and is jetted 66/70 right now. The dizzy is a fully mechanical Mallory Unilite with a hyfire coil. The problem that I am having is that the engine stumbles off idle and will backfire through the carb quite frequently. I think I may have the a/f mixture going pretty well but I think the timing is coming in way too late and causing it to fire retarded (which is why I am glad the carb has the power valve delete). Looking for any input that can get this beast running properly so that it can become my daily driver.

What is the intended use for this engine? Strip - Street - Crusin?

Street/strip DD. I've done quite a bit of tuning and have made pretty good progress, I took the carb apart and replaced all the gaskets and reset the float levels. My latest problem is that the boosters were kicking in way too early and dumping too much fuel and now my plugs are carbon fouled. I've got double shifts for the next couple days, but as soon as I get a day off I'll be right back at it!

check timing,and the advance first