Summary

00:00 - Last question here from Backyard Auto who's asked, do you suggest lapping Inconel coated valves? OK this is another controversial topic here, regardless of whether your valves are coated or what material they're made out of.
00:16 An old school technique of getting your valves to seat properly was to lap them.
00:22 So this involves using a valve grinding paste and basically a little suction cup on the head of the valve and you rotate it backwards and forwards, and the abrasive paste basically cuts into the valve seat and the valve material.
00:33 That's not a technique that's been used now for a long time and the reason for that is that lapping your valves like this actually ends up with the valve seat and the valve surface concave and convex respectively.
00:48 And while it will result in a valve that seats quite nicely when the engine's cold, it almost guarantees that once everything gets up to operating temperature, your valves won't seat properly.
00:57 So these days the technique that is used is to simply have precision cut valve seats and precision cut angles on the valve faces and basically leave them like that.
01:09 On that note though, even with really good quality cutting equipment, it is likely that you're going to end up with some minor chatter on the valve seat or the valve face.
01:20 So what we can do is use a very light lapping compound, so not an agressive abrasive, just a very light lapping compound, we're not really lapping the valves as such, instead what we're doing is just running them very lightly on the valve seat and we end up just removing any of those high surfaces.
01:38 We're not trying to grind the valve seat down.
01:40 And this will also give us a nice grey line that shows us where the valve is seating.
01:45 So I wouldn't necessarily refer to this as lapping the valves but important to understand the differences there.
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