Mark, To give you more information regarding my 1972 240z: The camshaft installed is a Schneider 274-F,with new valve springs, retainers and .175 Lash Pads. I also changed to new nissan oem rocker arms. The specifications of this cam are the following: Intake Duration (gross): 274 Exhaust Duration (gross): 274 Intake Duration (.050â€): 215 Exhaust Duration (.050â€): 215 Intake Valve Lift*: .480" Exhaust Valve Lift*: .480" Intake Valve Lash: .008" Exhaust Valve Lash: .010" RPM Range: 1800-6000 2. My car has a L26 crank which makes the motor 79 mm stroke instead of the stock 73.7 mm stock bore is 83 mm for the L24 and the L26 motors. My block has been bored out 1 mm to compensate for wear that makes my motor a 2.627 liter motor and has a E88 head from 1972 will give about 8.7 to 1 compression I have a pertronix 1761 ignitor installed in the stock distributor. Any other information that can help you diagnose and solve my cylinder 4 issue?