[GB SISSON]

Originally Posted by Bored&Stroked

Your seat width looks quite wide on the valve that was lapped. Are you doing multi-angle seats - such that you can control the width and placement of the 45 degree seat?

You want the seat further away from the edge of the valve on the exhausts (similar to the one shown) and the widths should be different between intakes and exhausts.

I shoot for about .060 to .070 on the exhausts and about .045 or so on the intakes. You need a wider seat on the exhaust seats so they don't burn and also to transfer heat. The valve shown has too wide of a seat for my liking.

Typically, you'll see folks talk about 3 seat angles to control location and width - the standard is 15, 45 and 60 - though on flatheads I'll use maybe 30 degrees on the top to set the outer seat location on the valves.

Thanks, and strangley enough I just came up to the house and read this as I finished lapping all the intakes and labeling them. I thought all the intakes looked much narrower than that one. In fact I was worried they were too narrow. Wife and I are running to town in a few minutes, but I'll get a pic of the 8 I just did and get it off quickly. I kept womdering why that one was wide. Les told me he did a 3 angle valve seat. BRB.