Question on lapping valves

Jeff Stout · 07-13-2016, 05:33 PM

This is on a Harley. I ported a set of heads ( getting ready for stock eliminator LOL). Replaced the valve guides and reamed to .002 to .003 stem clearance. Using old valves and cut face to 45 degree with a 30 degree under cut. Went to head with a kwik way and cut seat to 33-45-65 degree. Lapped valve and checked with flashlight through port and can see light past seat and valve face. Without valve spring and just the weight of valve. After about 4 attempts I no longer see light passing through. I faced new stones a couple times to make sure they were correct. Valve isn't bent. I don't have a way to check seat to guide but guides have a lip and bottom out in head properly I believe. I guess my question is do you need to lap along time to get a 100% seal around seat and valve face? I know its not a class motor but you guys give good honest help. Thanks Jeff

07-13-2016, 05:33 PM	#1
Jeff Stout VIP Member Join Date: Dec 2001 Location: phoenix Posts: 1,409 Likes: 53 Liked 655 Times in 255 Posts	Question on lapping valves This is on a Harley. I ported a set of heads ( getting ready for stock eliminator LOL). Replaced the valve guides and reamed to .002 to .003 stem clearance. Using old valves and cut face to 45 degree with a 30 degree under cut. Went to head with a kwik way and cut seat to 33-45-65 degree. Lapped valve and checked with flashlight through port and can see light past seat and valve face. Without valve spring and just the weight of valve. After about 4 attempts I no longer see light passing through. I faced new stones a couple times to make sure they were correct. Valve isn't bent. I don't have a way to check seat to guide but guides have a lip and bottom out in head properly I believe. I guess my question is do you need to lap along time to get a 100% seal around seat and valve face? I know its not a class motor but you guys give good honest help. Thanks Jeff