ok so i've been having problems with my motor back firing/spitting fuel out carb at idle. long story short if you let it idle and try to give it gas it would back fire. Got ahold of the guy who built it ,broke it in and set up the timing told him what it was doing and he said sounded like a problem with the dizzy not advanceing right at idle told me to try a lighter spring. so i did that and it seems to have fixed the problem at idle. the only time it will pop now is when its idle and i try to give it a quick mash to the floor what could that be?

So since it was finaly running half decent i decided to put on the air cleaner and go around the block with no hood sounded great. but when at a stop i give it gas and it would like die/fall on its face. I'm leaning towards the accelerator pump not being adjusted right. when by a holley manuel said for .010 clearance when at idle is that 10thousand or 1hundred thousands?

here is a vid of the popping before the new springs. I crank it a bit till i get oil pressure before i start. also vid would have been longer but the batteries died.
http://www.youtube.com/watch?v=J7qCZjzL8oc

 

There's supposed to be NO CLEARANCE WHATSOEVER at idle. The pump should start pumping THE ABSOLUTE INSTANT the throttles start to move.

What you're supposed to do is, BOTTOM OUT the pump lever with one hand; with your second hand, open the throttle to WOT; then with your 3rd and 4th hands, adjust the duration screw (the one that sticks through the link piece, with the spring around it) until there's AT LEAST .010" of clearance between that and the lever.

Set like that, the pump lever should rest, with tension, against the cam; and get a full stroke of fuel, without bottoming out at WOT and bending or breaking anything.

 

Your timing sounds retarded. That's also why you have to crank the crap out of it just to get it to start. What is the initial set at? You need to unhook the vacuum advance (plug it at the carb), turn your idle as low as it will go and then set your initial to about 10* advance. With real light springs, you need to turn the idle WAY down to set your initial or you will already be into the mechanical advance.