How-To: Lap Valves (by hand and drill method explained)

Hi. I buy new valves tomorrow fpr an old cylinderhead, the head looks good. Do i do lapping before i put the new valves in or? Its a car engine from 2011. Or do i just put valves in the head as them are from new

You need a variable speed reversible drill i go way slower and check often, i haven't gone too far yet doing it like that, if the seat width goes past 2mm thats where trouble begins

I have gotten great results with a drill. You have to set it for low speed and not use a lot of force, just lightly. Also, you have to go forward, reverse again and again. Do not tighten the chuck too far. You want no marks and it does not take a lot if you just go easy and reverse over and over again. If they are fixable it leaves a beautiful even finish. When too pitted you have to go to a pro unless you have the tools especially for valve guides and if the heads are full of gunky sludge.

Get your lapping stick and thin it down in the lathe where your hands would be , you'll find it a lot easier, get your valves refaced , your seats need top and throat cut to get the seat ⅓ down and ⅔ up on the valve face . Get the seat width right and it will cut the carbon .Yes I am an engine reconditioner by trade , and was in charge of the head bay for years .

A cordless screwdriver is a better option than a drill, BTW. Lighter and slower.

If you lap valves with a drill you have speed control, only a fool would drill lap flat out. Secondly, you don't just lap in one direction, use the reverse switch, thirdly you lift the valve every now and then. Some people just don't have much of a clue.

Drill speed ridiculous. All the paste will fly out. Slow and steady ,

Good stuff!

There are a lot more issues than performance with worn seats. For example, the fact that you may not be able to get valve lash in spec. Also your valve spring install height changes which can make it easier to float or drop a valve at high rpm

Lapping doesn't do any good period ,take it to a good machine shop and have the valve and seat cut lol

such a bad way to do it with a drill. going way to fast to start.

Stick to motorcycles

Does brand new factory installed valves need this process too?

Put a rubber hose on the valve then a bolt in the other end then slap that fucker In the drill now you got more room to wiggle the valve up and down to avoid the grooves works like a champ

Slow rotation 3 seconds / reverse slow rotation 3 seconds / forward slow rotation.........
Medium Not excessive pressure. Let the grit do the work. Putting too much pressure squishes it right out.

you alternate turning by hand but you refuse to use reverse on your drill? What gives?

When I run it with a drill I put a rubber hose on the end of the valve and then of course on anything that are going the drill whether it be a screw usually a screw sometimes a drill bit which obviously don't stick a drill bit up in the head but I stick it inside the rubber too the river too for one it won't let you pull so hard and also it will start to bind up we're having it directly hooked to the drill what you've done this many times so I'm sure you can feel it me I've never done it worse directly hooked to the drill and the reason being is because to me it's too tired of a situation I want to have some flex and some give if it needs to have it and that rubber too will give me that and I just move it up and down you know as I'm turning it and I turn it both directions reverse and forward and it does a pretty good job that way I never have actually hooked to the valve itself with my drill I just never have been that confident with it not saying to God wouldn't keep it straight and all that not really worried about that the rubber tube just gives me an opportunity to move the valve up and down you know and and the rubber if it gets it gets some kind of binded or gets too much pressure whatever the rubber would just roll up and it gives me that you know that gives so that I'm not damaging anything but that's just the way I do it

I repair engines since young age and I always use the drill and never had any grooves like you describe in your drowing. I use to alternate the spinning speed and direction, pushing in and out with different pressure .
I also start with coarse granulation paste using slow speed and little pressure and finnish with fine granulation and more pressure.

There is a tool for your drill that rotates just like your doing it by hand great to start off with and finish by hand .we also have a 2 course vale grinding paste course and fine this way saves a lot of time

i suppose you had low compression the way to tell rings or valves is add a spoon of mtr oil in plug hole if it helps comp its the rings leaking if no help it is the valves leaking

drill is a no no on laping all you need to do is polish the surface for air seal

Details regarding laping is good in reaching quality I'm having a question when we replaced with a new tappet valve's could I done any modifications to the top of the stem reasoning me some issues while clearance seating isn't correct at the bottom of shims and camshafts.

You should also do it in reverse

Probably best video for newbie s.

so diligent and clean

Uncle Tony is laughing at this clown.

Look at the state of the valves on the back where the fuel is pulled in...that's perfectly cleaned before I start lapping

There is a adapter tool with suction cups which does the left right turn as well. Does the same job as the the wooden handle tools. The drill version is a big NO NO... we figured that out ages ago. Only in 3rd world countries 14year old do that in some sand floor backyopard garages.
There is way more to do to a valve job than just lapping a bit. A valve job starts with a 3 angle valve seat cut. Lapping is just a small detail of 24min work for a 24V head. Still thanks for sharing!

You have the Drill on High Speed...
I Put Mine on the Lowest Speed Setting and Everything Looks Just Fine...

I mixed my bike valves... exhaust side. Any advice?

Nice shop Bro, how long ya been doing it?

Yes, it works GREAT!

so if i buy new valves do i have to lap them before i put back in the head. also there not titanium

can you say something about 3-angle vale seats? I intend to lap the valves (by hand) in my Honda J-series engine. I am told it has 3-sngle seats. I assume the middle cut is a full mating surface, and the two outer cuts would be partial mating surfaces with tolerances/specs as you mention. Anything else you would add?

Hand is the best method 😊

You guys that are using drills you're going way too fast! I work in a machine shop I am a professional engine rebuilder I have lapped well over 1,000 valves and I do use the drill in same manner this feller did he but he is using Way too much speed! You want to simulate the speed of doing it by hand which is barely pressing the trigger of that drill. You also need to spend in One direction until it gets quiet push the valve out switch the drill spit it in the other direction back and forth just like that.

Dude you are going waaay too fast! You want about a tenth of that speed!!

So use a random orbital sander attached to the valve, good to know.

Thank you

Thank you very good info for me thank you

Could always buy a cheap hot glue gun for the toilet plunger it might actually stay on the valve

#1 If you don't understand how to grind, file, sand then you shouldn't use a drill on your valves. Spinning the drill that fast as this video shows is ridiculous. Absolutely laughable. I was shocked to say the least watching that drill hit full speed. Drills can be used very very effectively but if you are spinning the valve that fast (including the valve grinding compound) then you are being careless/clueless or both.

Good work thankyousir

Excellent explanation. Thank you!

i like lapping them with a 6 inch piece of 3/8 rubber hose attached...then i clean everything ,put the valve back in and hold the valve closed with only my finger then pour gas in the port to check it...if there is any wetness at all do it again

Can we clean off the carbon deposits on the valves using petrol n scotchbrite instead? Intention is to use a softer material than metal , so as not to remove the metal material of the valve... TIA for the advice...

Great work

Check out some Neway cutters for diy there awesome

Thank you for sharing this!!!