Ok - Bluf: Built a mod 351W and dropped it into a 67 mustang hardtop.

Engine came from a late 69 Torino and the numbers code to the "higher nodular iron" block

351W - .30 over
Crank ground
New pistons rings
New valves
New Valve springs and seals
pushrods, conrods and rockers stock (were really clean)

Cam - 268 lift comp cams hydraulic
Carb - Holly 4160
Ignition - Pertronix w/ matching pertronix coil

Ok - The engine ran beautifully, and i heard a loud clicking from the valves so I went back and opened up the valve covers and retightened them.

Now I'm missing on cylinder #4. (Went back and reinstalled the points - no change) Changed the wires, cap and rotor as well.

Could I have overtightened the rockers and shut off the valves from opening? Would that cause the cylinder to miss, and if I did, how much damage did I just do to my engine by running it with the valves not opening?

Thanks,
Frank

 

Most likely, you tightened one too much causing the valve to not CLOSE. Go back and reajust them. Make sure you are on the low side of the cam when adjusting, tighten while spinning the pushrod with your fingers until there is no slack (it will no longer spin) then tighten another 1/2 turn.

A quick check is to pull the plug and crank while covering the hole with your finger to see if you have any compression.