I just replaced a blown headgasket and timing chain and I'm trying to start my engine for the first time since that, it doesnt start and backfires from the intake. I emptied the tank and put new gas in it. The injectors are brand new but 2 are leaking and I'm going to fix that tommorow. The compression is good. Any ideas on what this might be if not just the leaky injectors?

 

Ummm...valve timing outa' whack...my guess

 

When you changed the head gasket, did you remove the distributor? If so, are you certain you put it back in correctly? Easy to have it go in with the crankshaft 180° out of phase.

Also, are you certain the harmonic balancer ON the crankshaft isn't slipped out of position? It has a rubber piece inside that's known to get old and brittle, and allows it to slip on the crankshaft. Make sure that when the harmonic balancer is indicating #1 TDC, it really IS there.
Double check that the position of the piston is at it's TDC position, and that both it's valves are completely relaxed. Easy to check. Put a straw in through the spark plug hole, and see if it's at TDC.

Absolutely verify all the valves are adjusted properly.

Good luck to you!
Pat☺