Picky 4.3Any help

[hvachelp]

1996 chevy Cheyenne. Long story short, second engine after 600 miles on a mabbco long block, started knocking. This one was machined correctly and assembled over the winter by me, with meticulous attention to detail. I cant get it to start. distributor is correct position, dead on 6 mark when TDC. (triple checked) I have spark, correct fuel pressure. Brand new cap and rotor, Taylor wires about 50 ohms end to end. Can see RPM on my scan tool, Launch X431 mini, so i know i'm seeing crank sensor, replaced cam sensor(inside distributor). ECT reading properly, IAT reading properly. MAP reading properly, TPS reading properly. Took it to dealership on mabbco motor for exact same thing, they said they had to flash computer(black box) for something. I cant do crank relearn until it is running. WTF am i missing. The truck was running prior to rebuild no problem except knocking. Motor grounds and body grounds have been checked and verified with ohm meter. Any help???

 

[Schurkey]

I cant get it to start. distributor is correct position, dead on 6 mark when TDC. (triple checked)

WHICH TDC? TDC Exhaust, or TDC Compression?

You will need four things for the engine to run:
1. A burnable fuel mixture (Not too rich, not too lean)
2. Spark ACROSS THE PLUG GAP at the right time (Spark TO the plug does not mean there's spark ACROSS the gap.)
3. Adequate compression. A cylinder should run at 100 psi cranking compression. More is better up to about 170 psi or so, depending on fuel octane, combustion chamber design, cam profile, etc.
4. Adequately-flowing exhaust system.

When you figure out which one(s) you don't have, you'll know what to fix.