[California98Civic]

Thanks for looking it up and posting.

I don't care about full load operation since I never floor it. And I don't care about lost torque anywhere on the power band because it will mean opening the throttle plate more and therefore reducing pumping losses. I am interested in economy here but I am equally interested in better emissions.

I read that overlap section you quote as mainly a warning about excessive overlap. So I chose to discount the warning because I am not exceeding Honda factory specs, just maximizing overlap within specs. The peak valve lift section you quote is interesting too, but both of these sections need to be thought of in the context of the four sections of EVO, EVC, IVO, and IVC.

So I studied the document again and made some changes. Thanks. These notes below are as much for me as anyone else with my SOHC 16 valve engine. If you have further thoughts, I would love to hear 'em.

Limitation
First, my engine's limitations. Because of the design of my SOHC 16 valve cylinder head:

(1) If I set LESS clearance (lash) I must have this combination of valve movement characteristics: EARLIER opening, LATER closing, LONGER duration, and HIGHER peak valve lift values.

(2) If I set MORE clearance (lash) I must have this combination of valve movement characteristics: LATER opening, EARLIER closing, SHORTER duration, and LOWER peak valve lift values.

NEW SETTING:
I am thinking to change the setting to MORE lash on the exhaust side and LESS lash on the intake side. I had set for less all around. MORE lash on the exhaust side would be better than the LESS lash I set yesterday. So now overlap does not get bigger than stock as I was planning. Instead it moves slightly closer to the intake side. Doing so should reduce the likelihood of fuel mix going straight into the CAT. What I lose in scavenging I will gain in EGR. More internal EGR in the cylinder and the intake manifold will improve efficiency at partial load and low RPMs (how I drive this car). It should also improve emissions by more completely burning fuel before combustion gasses escape.

That's in theory. It is a really minor set of changes, actually. So I am kinda overthinking it, but I am learning about the dynamics so that is maybe good for the future.

Questions that remain for me:
If these adjustments change burn and flow, O2 sensor and MAP sensor data to the ECU will also change. How might data changes affect how the ECU sets AFR and ignition timing? Could any changes from the ECU negate the valve adjustment mod?