Valve spring installed height
Some heads are not safe to increase the diameter even at stock depth without hitting water. If increasing the diameter on some small block chevy heads you have to place a shim on the seat and cut the pocket to the top of the shim to stay out of the water. The seat gets thinner as you increase the diameter.
Ran into this yesterday on the dyno. The motor started blowing water vapor out the breathers on breakin. Had to shut it down. This is what I found in the picture.
I agree for the most part. There are some applications where it makes sense to cut the seat. An example is the EQ magnum head. EDIT: ( I don’t know if this applies to the China EQ's) It has a very short installed spring height. Sometimes offset keepers/ retainers won't get you where you want to be. Luckily they have some room to cut.
Some heads are not safe to increase the diameter even at stock depth without hitting water. If increasing the diameter on some small block chevy heads you have to place a shim on the seat and cut the pocket to the top of the shim to stay out of the water. The seat gets thinner as you increase the diameter.
Ran into this yesterday on the dyno. The motor started blowing water vapor out the breathers on breakin. Had to shut it down. This is what I found in the picture.
