davidb wrote:Please help. Some time ago, after really bad experiences with local shops, I decided to do my own valve jobs. I bought Neway cutters, a seat indicator and started cutting. As I recall, I managed to get concentrically to with in .002 and really good sealing, about two percent leakage with my leakdown set up, which only measures valve leakage, (v. the seven percent I was getting from the pros)
The problem is: one of my exhaust valves was sunken pretty deep I was OK re. installed height but it was pretty deep. I've run this head in six races ( it's in a road racer) and it's been great, really good compression, leakdown, and power, but now, I've been told that I'm risking disaster and a broken valve on that sunken valve. True? or am I OK.
This is a 16v, 1.6 Miata.
davidb wrote:Bobqzzi: Thanks, and thanks for the spelling help too.
jsgarage; That's what I expected; I'm using stainless valves with thicker heads; I'm beginning to think that the "guru is B.S.ing me.
Thanks to this discussion, I'm beginning to sleep better at night.
tflow: I simply bought the required carbide cutters, and a cocentricity indicator, and,importantly, a bottle of red layout dye.
I also have an old Souix valve grinder with a collet, but valves are so cheap that I don't bother with it.
I think the cutters are capable of producing a really good seat, that seals pretty well, but, man is it time consuming!
They seem to tear the seat material if too much pressure is used.
I'm convinced that my problem with sunken seats has more to do with trying to correct a professional valve job that was previously done with a CNC mill, than with my cutters.
After the CNC screwing, I took the head to a shop with a Serdi and they made it even worse (10% leakage).