I'm rebuilding the head on a H22a (JDM) engine out of a 1995 prelude. The valve dimensions are all within spec but when measuring the valve stem installed height I'm getting silly numbers (~40mm for inlet and outlet) as opposed to the specified values of 37.7 +- and little bit specified in the Haynes manual.

Now I am measuring from the alloy of the head where the valve guides meet the alloy to the tip of the valve with the valve fully seated. Perhaps the installed height is measured with the valve seats in place over the valve guides? That would knock off a few mm from the measurement?

 

From the sound of it, your measuring in the correct place, however the valveseats must be installed...You are checking the FINAL valvestem installed height, not before installing and cutting the valve seats...
Valveseats and guides should already be installed so you can get a final valvestem installed height...
They make a tool specifically for this job so you can get an accurate measurement (if you dont have one)

 

Ok thanks, so measured with the valve spring seats in place. I'm using the depth gauge on digital calipers so confident of the measurement I am getting.

If the installed valve stem height is past the maximum anyway is there any known way to get around this (shorter valve stems or valve seat inserts?) or do I really have to replace the head?

Thanks!

 

Are you talking about the valve seats?
or the lower base retainer for the valvespring?
Think i mis-understood you...
If the installed height is too much, you may be able to replace just the valveseats...Has the car had previous valvejobs performed?

 

Ah ok, sorry. It must be the lower base retainer (valve spring seat?) - the spring sits on this, its the other end from the valve retainer/keepers.

I'm hoping the installed valve stem height is measured from the lower base retainer to the valve tip (which the rocker arms press on) - otherwise things are way out of spec.

I doubt the car has had any work before this.

 

you measure installed height with everything in place and the most accurate way is with an expander like:



make sure the spring seat is in place, shrink the tool, install retainers and locks and then spin the expander out and it will measure the distance.

They make anything and everything between to change installed height (+/- .050" locks and retainers) but the easiest way to decrease installed height is to add shims under the spring seat.

They sell shims as small as .010"

 

If the valves are too long you can have the tips ground shorter but there are limits to how much can be taken off because the tips are hardened. You may also want to check the seats because it is possible they are sunk too far into the head.