So I got new valves, cut new seats in, and lapped the valves on H22a P13 head. The new heights are measuring 40mm roughly off the head, without the spring seat installed. The stem install height spec for the h22 is around 37-38mm. I can't cut 2mm off the tip of the valves it'll be too close to the groove where the keepers go. How is this possible? It doesn't look that deep from faces of the valves. I get much better numbers with the spring seat installed. I cannot find any information on this.

 

Where did you get the install height numbers from ?

 

The service manual.

 

So, you answered your own question then. You have cut the valve seats too deep. You must either replace them or replace the cylinder head. You could try running it... if you can adjust the valves, you might take a chance.

 

Is the valve stem height measured as installed with springs/retainers?

 

Absolutely... just as illustrated in the above photo from the Honda FSM. When you sink the head of the valve deep into the valve seat, more of the stem protrudes back up toward the rocker arm - increasing valve spring install height. The problem with this is that increasing install height REDUCES spring rate, which reduces the springs ability to resist valve float. With aftermarket valve springs (which are usually higher rates compared to the OE springs), you may be able to offset this phenomenon. You must also focus on rocker arm geometry and the ability to adjust the valve tappet... if these are good, you can effectively run it.

 

Roger that. I think I understand.

 

That makes sense, I should be good then.