My thoughts on valve lapping

This is a video to make you think about it. It’s not about me saying whether it’s right or wrong. One thing is for sure you can make valve seal worse by lapping badly!!

[sjcvs]

Even when I’ve built multi valve 500-600bhp engines I still manually lap valves by hand with a fine paste exactly the same way you taught me to do two decades or so ago when building mini engines in your workshop :)

Good engineering is still good engineering and it frustrates me that for something that ultimately only takes a few minutes a valve people are looking for a short cut that isn’t needed.

[markgutter]

You are the man. You are one of the two people on the Mini forums who's reply i rely on. Hourly rates for skill and good knowledge has always demanded a fair price. Thank you.

[HREIRL]

I think it’s completely fair to say this is one of the best videos available now on the internet regarding valve seat seat seal. There will be an order on its way in the new year for some of this valve paste. Top top job mister Dodd

[tonyjenkins]

Glad I found this. Just lapped valves into a Mini Cooper S. With the head upside down each pod of 4 holds water with no leakage after 2 hours.
With paint thinner ever exhaust valve leaked. Permatex grinding compound is supposed to start at 120 and end up at 200.
I've ordered Loctite Clover 280 and Wheeler 600. Only choices i could find. This video really helped in understanding how smooth is perfect and what to expect at 200. If i can make the jump from 280 to 600, i will do a leakdown test with oil in the piston and report back.

[travisrichardson]

As a beginner, great video with easy to understand concepts.

[anthonybennett]

Spot on as usual, was doing this in the mid 70s when I served my time on jags, the garage had a name for head work, coarse paste was banned from the workshop as it would pocket the valve seats, a good valve job would cure most hot starting problems, but not a quick job on a jag though.

[furyfantoo]

Excellent video showing different results from different lapping methods, and also showing how to verify your work.
One thing to note - when watching the needle-sweep of leakage, be aware that the leakage/needle sweep is NON-linear, so make sure to compare the same range on the gauge (i.e. from 50psi to 40psi) when making comparisons. Obviously the 1000-grit valve is noticeably different across the entire range.

[OldRodder]

Excellent tutorial, answered all my questions.... thanks

[georgesanderson]

Amazing info and demonstration cheers!!!

[riadhch]

You're great mister the explanation was perfect and the amount of information you shared are countless please accept my full respect and thank you for you time and for every think you shared good luck in your job and on your life

[cimfur]

No ego so refreshing. Only reason I clicked on the video is the title.

[ApprenticeGM]

Great to see a guy become an expert in a specialised field through hands-on research and data collection. Particularly like building your own tools to test, and making your own paste. Thanks for sharing, it all makes sense to me!

[davidyendoll]

Thanks ! I never knew the fine paste I have used for years was not fine enough . Ta muchly . And vacuum testing .... damn, you are worth listening to !

[ericgeber]

Helped me alot to get my valve seats DIALED! 😊

[kathysarmcandy]

I like a swab of Dykem before lapping. Caught many seats not concentric that way.

[alistairrussell]

Another great informative vide. Great to see you sharing knowledge and experience.

[russellduffy]

Great video! Thanks for the testing idea using the press and rubber mat. I was able to do that today and it's nice to know that it's going to be OK before going to the trouble to put things back together. Thanks.

[andyfry]

Hi, I watched and listened and it all makes perfect sense given the results and comparisons between valve paste grades. These findings only ever come from someone like you who has done lots of homework! Great stuff 😊

[MiniMattTV]

Always nice to learn something new, I’d only watched the first half of this before I saw you yesterday, definitely going to check what paste I have and find something better

[TonyLiveTV]

Good video. I agree pressurizing the head to test is a good way to test the seal. This is how a good shop would do it. That said, you mentioned in the video the reason you don’t use vacuum for test is because of leakage around the stem. But there is a solution for this. I use surgical tubing on the stem and valve to create a 100% air tight seal and it works perfectly. I have a video showing this method.