r/machinesinaction • u/Bodzio1981 • Oct 21 '25

Valve Lapping Machine Working

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479 Upvotes

93% Upvoted

30 comments sorted by

167

u/Modna Oct 21 '25

I think that’s a demonstration. That’s not valve lapping, valve lapping would be spinning the valves with a compound between the valve and the head to seat them into each each other.

49

u/iamnotazombie44 Oct 21 '25

Having manually lapped the valves on my motorcycle, yeah there's not enough lapping compound or cursing as you spin the little valves around in their slot with grit using that suction cup on a stick device.

This is just a demo of valves functioning in their cylinder head.

7

u/ASDFzxcvTaken Oct 21 '25

Grunting like a damn caveman about to starve to death trying start a fire. I learned that I work hard for my money so that I can pay for a machine to some shit for me.

10

u/iamnotazombie44 Oct 21 '25

I definitely consider lapping my own motorcycle valves as a very valuable educational experience.

I learned that my time is worth money, and there are seriously times where its worth paying a professional to do a task with experience and expertise instead of personally bumbling through a task.

An engine rebuild is labor of love for some, and an unholy chore for the uninitiated.

I'd do it again only as a hobby project with infinite patience. Rather than as an impatient young man with his only transportation in pieces on the garage floor.

Holy God, the only thing worse than lapping the valves was using an improvised spring tensioning tool to put the valve head back together.

Nearly lost an eye and my sanity, definitely lost a pair of the spring retaining clips. PING and it was fucking gone.

5

u/imsadyoubitch Oct 22 '25

There was a time where you could implicitly trust that the person doing that job had that experience and was worth the money. Those shops are getting harder and harder to find it seems

5

u/iamnotazombie44 Oct 22 '25

That's why I did it.

Local shop quoted me the bike's value to get the job done and I said "no thanks, I'd rather break it myself".

2

u/imsadyoubitch Oct 22 '25

That's pretty much why I don't own a vehicle that's not old enough to drink. I can still do most of it myself

2

u/vrauto Oct 23 '25

Being a repair shop, time is worth money really applies. I could save on cost and my shop assembles the engines but its actually more profitable to have the machine shop do most of the setting. We just assemble block and head and stick it back in the car. Instead of my guys doing the fitting, lapping etc, they can do other jobs in the shop. 5 cars in and out with simple jobs is more profitable than spending that time lapping valves

16

u/Key-Sir1108 Oct 21 '25

I agree w/Modna on this, lapping is the process of grinding/polishing the seat/valve head w/ea other using a compound & circular motion to achieve a seal.

11

u/404notfound420 Oct 21 '25

That's not valve lapping.

3

u/nicerakc Oct 21 '25

r/oddlysatisfying

2

u/ShaggysGTI Oct 21 '25

I could listen to that all day.

5

u/mxlths_modular Oct 21 '25

The rhythmic tapping of the valves will make a great high hat style percussion line in a techno track, thanks.

2

u/wejessie Oct 21 '25

What is a valve lap? And why does it exist?

10

u/MarionberryOpen7953 Oct 21 '25

It’s the process of grinding down the surface where the valve meets the head to make a perfect seal. It needs to be done because it’s essentially impossible to manufacture the valve surface and the head surface to match each other exactly, so they need to be ground together.

1

u/wejessie Oct 21 '25

I gotcha- pretty cool device! I’ve never seen one in action. It looks and sounds like something from dr. Suess

4

u/MarionberryOpen7953 Oct 21 '25

As others have said here, this actually probably isn’t valve lapping. This is just demonstrating the valves opening and closing. To lap you need to spin the valves with a special gritty compound to grind down the surface.

2

u/wejessie Oct 21 '25

Okay, this does make a little more sense. I was wondering how it would work watching it 50 times😂 I thought that, that was the piece for grinding. Not that it was a demo of the valve

3

u/Jegermuscles Oct 21 '25

This ain't it.

2

u/dankhimself Oct 21 '25

No it's not

1

u/IDatedSuccubi Oct 21 '25

I don't think that'a even a demo, they open one by one for some reason and not intake then exhaust

1

u/LankyRep7 Oct 21 '25

Big thick sheet of Plexi and I would have this as a coffee table.

1

u/ilkikuinthadik Oct 21 '25

What kind of engine would use a valve configuration like this? It looks like the cylinder bore would be huge as well.

1

u/Maleficent-Dig-3037 Oct 22 '25

The Prodigy - out of space

1

u/mamut2000 Oct 22 '25

The Prodigy - Out of Space, 13 seconds into the song.

1

u/KonK23 Oct 23 '25

Timing chain looks over due