[petehoovie]

Originally Posted by GB SISSON

My big valve day started out slowly. My valve face grinder came with an aftermarket electric submersible pump for the coolant. I tried it back when I got it and it whirred so I thought was good. Nope, took it apart 3 times, cleaned, inspected, motor spins, nice o ring seal, nylon impeller no damage. Won't pump a drop. So I go to the backup other sioux, same model. Belt drive pump but broken cast iron bracket and no belt. Wasted the morning. After lunch I rigged up a gravity feed. Was a pain refilling and messy. Used tractor hydraulic fluid. So, now I have them all ground and have questions.
Margins. I have read quite a bit but a lot of valve info is for overheads and stuff that's gonna be raced at 8000 rpms etc. Seems intake valves can have fairly thin margins as incoming air cools them. Exhausts want like .10" thick margins. These ar my two thinnest exhaust valves after grinding. I don't see that thickness, but somehow they seem ok. You can see I did a quick lap on one. One thing about the margins confuses me. Does a valve ever get ground around it's circumference to attain a thicker margin or is that self defeating. Seems a thick valve transfers heat to the seat better, and a thin margine burns easier. Do these valves look OK for exhaust valves? The intakes are all about this thick, but their stems measure a little bigger, generally .341 with exhausts .0005 smaller.