Valve lapping

[mdmcinti]

Did some research and it turns out that cam is advanced 4 degrees so it’s intake center line is at 112 degrees. Basically it gives the cam low end and the exhaust comes later. I might consider it if it’s still on sale lol.

 

[MLRTYME]

When I replace them cam and lifters on my Yukon xl. Since then heads are going to be off, I was going to clean and rebuild them on my kitchen table. I was seeing videos and threads where people would lap the valves when doing this. I also have read where a member on here did a cam swap and afm delete on his 6.2 Denali and and machine shop didn’t lap the valves because they sealed perfectly fine. I was planning on removing the valves and doing the scotch brite cleaning method with a drill and the help of of an acetone/tranny fluid mix ( there is a video on YouTube of this working wonders on carbon like magic). What are your takes on this?

Btw I am going to drop in a summit 8718R1 cam into my rig since it can run on stock tune and springs until I have funds for a tune and some ls6 springs.

Re: Lapping Valves--- When new, valve seats and valve heads will wear a unique pattern with one another as the engine runs (similar to the old school flat tappet lifter and cam lobe wearing a unique pattern) and this helps provide the seal. The concept of lapping basically clears that pre-worn surface and builds a new unique wear pattern so the valve seat and valve head can start fresh. Most commonly done when someone has the valve seats refaced (but is reusing old valves) or vice versa. Lapping isn't a terrible idea, but if you keep the valves in the same cylinder going in as the one they came out of...and you're not doing any resurfacing to the valve seat...the benefits will be negligible.

If you have some time and you don't mind a little elbow grease...it's not a bad thing. Just know that the effort may provide minimal results if not necessary.

 

[mdmcinti]

Re: Lapping Valves--- When new, valve seats and valve heads will wear a unique pattern with one another as the engine runs (similar to the old school flat tappet lifter and cam lobe wearing a unique pattern) and this helps provide the seal. The concept of lapping basically clears that pre-worn surface and builds a new unique wear pattern so the valve seat and valve head can start fresh. Most commonly done when someone has the valve seats refaced (but is reusing old valves) or vice versa. Lapping isn't a terrible idea, but if you keep the valves in the same cylinder going in as the one they came out of...and you're not doing any resurfacing to the valve seat...the benefits will be negligible.

If you have some time and you don't mind a little elbow grease...it's not a bad thing. Just know that the effort may provide minimal results if not necessary.

Thank you for that explanation. I probably won’t have to worry about doing it then since I am going to remove one valve at a time to clean an then reinstall with new seal and spring, then move to the next valve. Plus it’s another $10 I don’t have to spend on materials and then have to explain to the wife lol.