AQ120B Backfiring

"I have a 79 bayliner with a v

"I have a 79 bayliner with a volvo penta AQ120B i had to replace the head and timing belt, after i got the engine all back together the engine started right up and ran for 15-20 minutes then after i tourqued the heads to spec and ran the engine for another 15 minutes, it ran great then i changed the oil and washed off the engine with the batteries disconnected and let it sit in 90 degree dry weather for 3 days to go start it and nothing, i since then changed the cap, roter, points, plugs, wires and coil, now the engine will not start and backfires through the carb and or the exaust... Can Someone please help?"

"Likely you got the firing ord

"Likely you got the firing order incorrect, i.e. wires to the wrong plugs... it's easy to do.
Also... gap on the points...and did you check the static timing?"

firing order is corect 1-3-4-2

firing order is corect 1-3-4-2 gap on the points are set to .019 (new) and static timing is spot on..