Why does new 5.0 motor not have power and fires between 5 and 1 on distributor have checked timing gears?

There are two firing orders for the Ford 302. There is the standard 302 firing order of 1-5-4-2-6-3-7-8. Then there is the Ford 302 HO firing order which is 1-3-7-2-6-5-4-8. Make sure you are using the correct order. Set the #1 piston at top dead center (TDC) on the compression stroke. Now install the distributor so the rotor is pointed at the #1 plug connection on distributor cap.