Just finished doing the headgasket on my truck. Now cyl #4 isnt firing. I changed the plug, and plug wire and its still missing. The valves are adjusted correctly. What else could cause this? Any help would be appriciated.

 

# 4 injector? May be unhooked or gone bad.

 

Remember the basics on what it takes to make a motor run.

Air, Fuel, and Spark.

It's probably not an air issue if the rest of cylinders fire. So that leaves fuel and spark.

Put the plug in the wire and lay it across the top of the motor so you can see the gap. Make sure the hex part of the plug is touching metal and grounded. Then have someone turn the motor over and check if you cna see sparks jumping the gap. DO NOT HOLD THE PLUG WHILE DOING THIS. You will get shocked with however much juice your coil is putting out... many thousands of volts.

If you have spark then it's a fuel issue. If no spark...well you need a spark so fix that.

 

is the plug getting wet?

also, you may have busted a plug wire by accident while removing it(i know by experience, NGK wires don't like to let go of plugs!)

 

I had the exhaust valve on #4 way to tight. I think i took too long to adjust the valves the first time, and by the time i got to #4 the motor was cold.