I have an interesting problem I can't seem to solve. Several weeks ago, I checked my timing and as usual check the spark on all the plug wires. The #3 and #4 cylinders were misfiring. I quickly purchased another set of blue thunder wires and rechecked. No difference. I then checked the timing spocket on the cam to see if the chain had streched and decided to adjust the spocket ot hole #2.. After adjusting the spocket I noticed that there was no chain guide bolted to the front of the block. That combined with an oil leak from the main seal convinced me that I should go ahead and pull the front cover and replace the chain, tensioner, guides, main seal, distributor and install a turbo oil pump. To make a long story short, #3 still misfires. Any suggestions?

Keith

My first '73 240Z had a similar problem that came up soon after a tune up. It turned out to be a faulty spark plug! I would change that one plug out if you haven't already. also have you checked the valve adjustments?

-Dale-

Dale has you on the correct path.Ihave had the bad plug also.Check your distributor cap and remember plug wires can leak current across each other thru induction.Try to make sure your plug wires aren't touching each other at the distributor cap.Once I had to replace the distributor cam(the part that your point ride on and your rotor attaches.It was worn and allowed wobble.It caused timing drift as well. Daniel