GM-GMC: ADJUSTING VALVES AND MAKING SURE FIRING ORDER IS CORRECT., exhaust stroke, spark plug wire

Question
I have a 1977 gmc pickup with a 292 6 cyl. i put a new head gasket on but never marked my plug wires and after torqueing the head i put the push rods back in and though i thought i adjusted them right. i know now that im suppose to make sure no. 1 piston is tdc on the combustion stroke but im lost now on how to re-adjust the values. should i back the nuts off the rocker arms until i get no. 1 piston tdc or what? i think i can get my firing order correct though once i get vales right. i'm afraid im gonna blow it up, when i did try to start it it back fired first time out the carb and then exhaust. i appreciate any help. Brett

Answer
Turn the crankshaft with a ratchet and socket until the slot on the barmonic balancer lines up with the "0" or TDC mark on the timing tab that is mounted to the timing cover (these are the same items used to time the engine with a timing light).

Turn the engine clockwise when viewed from the radiator side of the engine.  When the marks are lined up, the engine is either on TDC of the compression stroke ot exhaust stroke and this can verified by looking at the the rocker arms on #1 cylinder.  TDC on the exhaust stroke will be indicated by the exhaust valve rocker arm depressing the exhaust valve.  TDC on the compression stroke will be indicated by both valves closed.

Put the distibutor in place with the rotor pointed at #1 spark plug wire.  Firing order is 1-5-3-6-2-4.  

Adjust the valves and you should be ready to start and time the engine with a timing light