OST-026: "My White Hatch"

[oldeskewltoy]

from another forum Wrote:We change the seat width not angle the valve grind.
.040 wide for hi-po stuff and .060 wide for street.
A quick hand lap with ultra fine paste and the valves seal
Instantly. Recleaned before assemble of course.

I'm told this is a track engine, typically I use 040 for intake and 060 for exhaust on 4AGs...

from another forum Wrote:How hard is it to grind the top of the valve? Measure the length of the valve before and after and use a grinding stone to cut it down?

Why do you run a 1 deg difference from the valve to the head? and what direction is "less"? Is the valve making contact with the head further inward or outward with the 1 deg difference? If it just seating pressure why not run a smaller seating surface?

Questions/suggestions are not a criticism I am asking because your work is beyond mine and the above is how I would do things

no criticism taken...

With the right equipment the valve is installed in a valve machine vice, and the machine will measure the tip, and then you set the grinder to take off the appropriate amount... very easy...

The contact point is further outward. As you break in the engine* the valve and seat pound together to form a nice tight seal. This pounding distorts the valve and seal slightly to provide an adequate seat and is why the valve may move up. The added degree on the valve allows for added filling on the initial opening and just before closing of the valve... think of it as an extra back cut

the exhaust valve ISN'T similarly cut, just the intake.


* another reason to break in an engine "hard"