How to lap valves in
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- Опубликовано: 7 сен 2024
- Valve 'lapping' or 'grinding' as it's known in some parts of the World is an important, though less common, procedure done to re-instate a good seal between the valve face and it's seat.
The valve's sealing surface can become damaged for many reasons and it's important to check it's condition both prior to engine strip down (leak down test) and when inspecting the cylinder head too. Let's face it, there's no point in rebuilding an engine that still has faults!
Modern cars with their lean burn engines, cleaner fuels, advanced steels and minimal oil burning tend to require this procedure less, in fact, some Yamaha valves can't be lapped in at all - only replaced!
Despite this it's still a skill that's still needed from time to time & if you haven't done it before then hopefully you'll find this video helpful.
If you have any questions please add them to the comments section and I'll get back to you as soon as I can.
Andy Mechanic 
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Finally, a no nonsense video on lapping valves. cheers buddy
Thank you so much for this! I’m lapping my first set of valves and had no idea if I was doing it right or mucking it up.
Cheers all the way from south Texas. good info.
Thank you for this video this is my first ever time taking apart a engine and dealing with valves I brought some new ones for the engine. So much appreciated
was thinking ive not seen you lap a valve yet .well you have covered it .
I had never seen this process being done. Your vids are definitely super interesting to watch. Thanks
Thankyou for this! Couldn't be more helpful!
Hello! I'm Thusharapriya Perera (a do it yourself - DIY mechanic) from Sri Lanka and spitting or spreading saliva on the rubber cup of the valve lapping hand tool is perceived as an awful & hasty act and also I personally don't like it. As a suggestion, use some water instead of using saliva on the rubber cup of the valve grinding hand tool. Thanks a lot and have a nice day.
Top stuff Andy. Last time I did that was on an A series 1340cc stage 2 head, 1991! Still have the paste!
+Pete Curran Thanks for the feedback Pete, yes, it was far more common back then to lap valves in. It's pretty rare now, even for me!
Very good process, Thanks.
Thanks!
Awesome video!
nice
Nice !
Hi Andy it sounded like you were going to use the valve that you lapped? I've always heard that once used for lapping the valve is no good?
Hi Steven, no, it's routine to lap valves during a cylinder head overhaul - it's important to ensure the valve seals correctly to prevent leakage of compression & combustion gasses. There are some titanium valves that you can't lap which is a pain
Cheers for the feedback. Andy
You didnt test for leaks?
How important is it for water to not leak through after lapping? I've lapped mine and looks good but if I put compressed air through the valve with the port filled up it bubbles. Does that really matter for a reliable el cheapo rebuild?
No. So long as water doesn't leak through under atmosphere pressure it'll be just fine
Cheers Andy
@Andy Mechanic awesome thanks mate. Love your videos.
Mommas spit on a napkin will cut the carbon right off!
That seat still looks like shit. Pitted.