Valve lapping
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Cruiser
Joined: Aug 2020
Posts: 146
Likes: 48
From: Louisville, Ky
Valve lapping
Here's another question for you all. Got the first head all lapped in and put the springs in. Poured gas in the combustion chamber. After twenty minutes the ports were still dry. After thirty minutes the intake side had about a half a thimble of gas in the port. Is this good enough or does it need to be lapped more?
Road Master
Joined: Mar 2012
Posts: 1,017
Likes: 981
From: Ohio
Sometimes lapping won't give a 100% seal. The valve and seat may need to have a light cut to clean them up enough to seal. Also if the valve is a little loose in the guide then lapping or cutting may not be 100% either.
Seasoned HDF Member
Joined: Jul 2014
Posts: 8,590
Likes: 3,358
From: Cental, MI
Lapping??? Never... maybe an expediant if Stranded!!!
Put a nice 3 angle job on...then Ruin it??
Not I
Look in the Original Service Manual for how it Should Be!!!!
BTW Even "new" valves get the Face skimmed/trued here!!!!
Put a nice 3 angle job on...then Ruin it??
Not I
Look in the Original Service Manual for how it Should Be!!!!
BTW Even "new" valves get the Face skimmed/trued here!!!!
Last edited by Racepres; Jun 13, 2024 at 08:02 AM.
Cruiser
Joined: May 2023
Posts: 118
Likes: 55
From: Ont.ca
Totally agree.Lapping gets rid of the interference angle that is meant to cut the carbon and it actually seals better in the short time the valve is closed.Laping is for lawnmower engines.
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Seasoned HDF Member
Joined: Jul 2014
Posts: 8,590
Likes: 3,358
From: Cental, MI
I won't Lap Any Engine...But, I own the Equipment...Lapping will get ya home if Stranded, Maybe. If Over Lapped (i believe that is a Thing) ie Extremely Wide Seat.. yer gonna Burn a Valve...
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Stellar HDF Member
Joined: Aug 2020
Posts: 3,174
Likes: 2,221
From: College Station, TX
If anything, I use Prussian Blus or some other marking fluid to detect low and high spots. But, that's after I cut the seats and valve faces to ensure they are true and the angle(s) is correct.
Paul
Paul
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