Hello. I am new to this forum. This one seems to be getting good results. I have a 94 silverado that I bought with cracked heads and decided to build back but has been a nightmare. New summit vortec heads comp cam 268/454 110 love separation. Bored 40 over. New everything except crank. Cannot get timing set properly. Base timing is 20 and with computer plugged up it’s 36-40 truck starts and idles fine but stumbles when accelerating. At base 0 and computer at 16 it pops through exhaust. Rebuilt TBI unit all new sensors. Need some help