Cam timing questions CIS 3.0 to 3.2 SC

[mike sampsel]

A.) The spec on 20/21 cam is 1.9 to 2.2 mm (with stand 1 mm lash at TDC). I find recommendations herein of advancing the setting to enhance low end drivability

So if I set my timing at say 2.2 mm it’s all good?

But I would need to verify interference (how many mm until the valve contacts the piston) at least at TDC?

Since I’m going to 3.2 liters with 98 mm pistons, maybe 2.0 mm on cam is good enough for low end drivability?

B.) if setting say 2.2, and there is “plenty” of room between piston and exhaust and intake, contact at TDC, is the clearance measurement at TDC alone good enough, or do I need multiple interference measurements across the cam rotation?

C.) when starting the process timing the left cam (number 1) and crank at Z1, I understand the left cam needs the mark (be it a dot, 930, or the keyway facing up) up. Where should the right cam be positioned? I know it’s mark needs to be down when timing on number 4.

D.) I plan on having all rockers installed prior to starting my timing process, based on knowledge passed on herein. Is there any advantage to just #1 and #4 only?

Maybe if you think you’ll need to tear down and add more gasket between the cylinder and the case? Easier to remove just one rocker per side I guess?

E.) chain tension for timing is only important to keep the cam/sprocket steady when moving the crank and cam still to get the right timing number? As long as the right number checks through multiple rotations after, the tension is not real critical?


Background

I’ve got JE 9.5 CR , 98 mm pistons, and the 20/21 grind webcam cams, stock valve springs and the Rev limiter will stay in play! And I know I’m far from the sheds-sharpest-tool and appreciate all inputs from the knowledge base. Im wanting to spend many hours defining the problem before I get to the solution. Maybe I should spin each question off in a separate thread, too late.