Is there a huge gain in lapping valves?

EthanP3

Member
Cl4 cam, 10.8 valve springs, stock air box, governor removed on Predator 212 hemi

Was thinking about lapping the valves(never done it before) and was wondering if it's even worth doing.
 

Chipg56

Member
It depends what you have. If they do not leak, don't touch them. If they leak a little bit, and the valves guides are good, try it. If the valve guides, seats or valves are shot, it will not help. A well machined valve job really doesn't need it.
 

paulkish

old fart
A well machined valve job really doesn't need it.
I think valve lapping is about being able to see how your machining came out, then adding to the quality of valve sealing.

It's long ago butt I think when I taught valve lapping via multiple angles on the seats that's why we looked at the line made by lapping.

Taught it years ago don't mean I knew squat about it then or remember squat about it now.
All of it was taught per book work info/theory and not from years of experience.

and... ????????????

among many other things and certifications I once had an Ohio teaching certificate to teach Auto Mechanics.
tooooo much junk in my head about mechanical stuff to remember anything ok. ... :(
 

Chipg56

Member
I think valve lapping is about being able to see how your machining came out, then adding to the quality of valve sealing.

It's long ago butt I think when I taught valve lapping via multiple angles on the seats that's why we looked at the line made by lapping.

Taught it years ago don't mean I knew squat about it then or remember squat about it now.
All of it was taught per book work info/theory and not from years of experience.

and... ????????????

among many other things and certifications I once had an Ohio teaching certificate to teach Auto Mechanics.
tooooo much junk in my head about mechanical stuff to remember anything ok. ... :(
Certainly a small amount of lapping after coating seat and valve with Dykem is a way to check the quality of the valve/seat fit. I should have added that I always lap with the Dykem, and I am not so perfect that additional lapping is sometimes needed. When lapping I prefer to end with a very fine grit, 2000 diamond.
 
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