Save Money And Lap Your Own Valves! [Measured Results]

*Please note that some heads WILL need a valve job (where the valves and/or seats have a new face machined at the correct angles). But it's not always needed. On top of saving money, you'll also avoid cutting material from the valves and seats (there's only so much to cut). Some valves also have a hardened surface which can be compromised by cutting.
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Data dump from all recent cylinder head videos:
thecarpassionchannel.com/head...
How to build your own valve testing tool as shown in the video
• Do You ACTUALLY Need A...
Jafromobile's Lapping Video (Highly recommend if you're doing this job):
• Not Another Valve Job!
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Valve Grinding Compound amzn.to/2X0oosL
Suction Cup Drumsticks amzn.to/2X0Dlek
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0:00 Intro
1:19 What Is Lapping?
2:07 How I'm Measuring The Sealing
3:39 How To Lap Valves
4:28 HPA
5:22 Basic Concept of Lapping
7:32 Pro Tip
10:53 Exhaust Valve Results
12:10 New Intake Valves
15:00 Intake Valve Results
16:34 Closing Thoughts

[@biggboysouth]

So per my old mans guidance who recently retired (so an old wise man of the trade) You lap the valves until you no longer see any shiny or un-lapped looking metal on both mating surfaces. Both should have a even matte finished look when done. I did see a couple spots on your lapped valve which to me looks like you could continue lapping to remove. I'm also far from an expert but I was blessed and fortunate enough to have my old man next to me giving guidance and inspection when I did my valves. Only exception would be if your valve has a deep pit of some sort which would require realistically too much lapping to remove, at that point if it's small you can probably just run it as is. If it's large then a new valve maybe in need.

[@FDB77]

Lmao wearing the glove with the cut fingers was a nice touch! 😂

[@jamesboonstoppel3596]

I have to state when testing for barometric pressure (positive or negative) that on earth we cannot exceed any less than 29 inHg. So the fact that your valves held at 29inHg means they were sealing up to a potential of 99.9%-100% Just a little thing we were taught in trade school for a/c applications - thought I'd share. Love your vids btw!

[@Projekt5.3]

Scientific method. This is what i like. No anecdotes, no old timer lore, hard data that proves claims. Well done sir!

[@joaomalhao]

Good job dude! Next time you do this job though try to spin the valves as far as you can either way. Short strokes, say if the valve only turns 1/4 turn either way, may result in a valve with a face matched to a seat only in a specific position, resulting in different sealing capability as it naturally spins around while the engine is running. You should be able to easily get two full valve rotations each direction by hand. Also, what you’re looking for is a uniform band of dull grey all around the valve face and seat. Keep up the good work!

[@DavidLieffring]

Only lap valves with short strokes to show if your valve or valve seat are uneven.

[@JamesChurchill3]

Thanks for putting all this stuff together man, I just got my spare engine for my NB that I'll be going through and refurbishing, these videos are an immense help!

[@vihangakeshan1017]

Same here!!!

[@EquiliMario]

God damn, this is definitely something I'm gonna try when I finally get the chance to pull my engine.

[@albietbeck]

Another thing to look out for is where the lapping marks are on the valve and seat. If its not in the middle it can indicate a valve that is too recessed or too proud, that will require the seats to be cut. Lapping isn't a replacement for machining and it wont have the same gains as a proper multi-angle valve job but its a great way to make sure your previous valve job is sealing when doing a rebuild. I've heard machinists say that if the valves need to be lapped after a valve job then the machining wasn't done correctly.

[@Nbomber]

Prussian blue is ideal for testing that. Put a little on the valve and drop them in to check the contact patch

[@user-qv1sy6ry9n]

Valve lapping can be used to correct small imperfections or to see where your valve face is hitting on the seat to low or too high depending on where you want it. It's not meant to fix valves or valve seats. They also make many different lapping compound grits.

[@Nbomber]

I messed up the timing on a NA 1.8 vauxhall engine, had to buy new exhaust valves. I cleaned the head, and cylinders, added the new valves and lapped them all in. On my kitchen table. That engine ran better than it had ever ran before. Noticeably more power all through the rev range. Wasnt an insane amount extra, but it was something. I didnt even deck the head. Engine had 80k miles on it. I wouldn't have done it unless I had to, or already had the head off, but it was well worth doing. Also a collet is way, way better than one of those suction cups. Also, cheap digital calipers, and a quick look in the cars service manual will tell you the width of the seat tolerance. Too wide and carbon isnt crushed up by the valve, too narrow (not an issue here), and the seat can deform from being smacked by the valve. Also, you get different grades of lapping compound, the Vauxhall manual said not to use coarse, but I did and then used fine. And was slightly over the width tolerance. But it worked out just fine.

[@drpiv]

Stop everything, CPC video to watch. Full send.

[@jannevot8515]

Smokers: we put cigarettes behind our ears. Construction workers: we put pencils behind our ears. Meanwhile Miata dad: 0:05

[@ebbonemint]

As a weekend mechanic My mentor is a greybearded lifetime hotrodder/GM master technician I ported/polished my own head on a 1.6T mini cooper, lapped in the new valves and was nearly 3 valves into reassembly when he walked by and made me do the old leakdown test WD40 a damp rag and compressed air, every single valve seat blew bubbles Re lapped every valve again, only three valves blew bubbles Re lapped a third time, reassembled and everything was air tight

[@ohhman9400]

Better grab a cold one. Miata dad's video's are always worth it

[@TFresh]

Always a quality video from you Greg good work! :)

[@mmodtomic7119]

I believe the exhaust valve seats are hardened and therefore take more lapping to get perfect like the intake valve seats.

[@JamieBainbridge]

Very cool. I've always wanted to try this myself. Interesting to see how quickly the tone changes as you grind down to the finer grit. Many years ago I ported a head myself but left the valves to the engine shop. I also just did my research and didn't go overboard, the engine shop guys said I did a really good job. I was stoked considering it was the first time I'd ever held a die grinder 😅

[@jamescave465]

Thanks for taking the time to do these videos. Really useful learning for those doing work I’m their MX5/Miatas

[@davo8802]

My dad always done his on valves and had some of the best performing engins around. I'm 48 and I remember him using those suction cups since I was riding a tricycle. Always remembered playing with them as well.

[@christianzinn7636]

Great Video! I learned a lot. I still got to get enough guts to do my valve seals myself. Thanks for what you are teaching the community. Best Always,

[@dave31764]

I love the measured before and after results. It’s a very good confident builder for my first valve lapping.

[@estewar03]

Cannot wait for some more canyon driving uploads as soon as everything is back together. Amazing content as always Greg.

[@coreythomas6229]

Love still seeing new stuff on the channel keep up the good work buddy

[@hewbambam]

Thanks for this video! It something that I'm going to have to do soon, I have a new head coming for my 1.6 and this is something I've never done

[@andrewjutras]

So cool to see real, measurable results!!!

[@badgermetal]

This is awesome. I don't have a Miata but I have a spare KA24E head for my hardbody I want to rebuild. Thanks for the bomb ass tips on saving me 💰!

[@ssarkees]

Awesome dude! You are a smart young man. I will be doing this on an old Ferrari this weekend. Thanks!

[@GTFour]

I'm learning so much from the way you present dude

[@danlohan4537]

Based on the exhaust valve results I would be tempted to replace the exhaust valves. Probably not worth the cost for marginal improvement but still tempting. I'm excited to see how well your hot vs cold compression/leak down values compare. Always wondered how valve jobs ensure proper seating during operation temperature.

[@scottmason2245]

Another awesome video from the miata dad. Cant wait to see some more mountain road driving and some more mad skids videos!!!

[@Lecherous_Rex]

great vid, lapped valves on power equipment for years. Still learned new stuff from this though, now we're going to have to make psyched and stoked into a new word and use it... get pstyched would be a good t shirt. Could write the words between a pair of pop up miata lights on the front

[@vettepwr23]

Nice video. This is very helpful as I am working on lapping my existing valves on a Toyota V6. I don’t have a vacuum tester though. The machine shop inspected my heads and identified the leaking valves. He told me that a valve job could be 700 and higher. He suggested that I lap the valves myself and replace the seals. He then said to come back and resurface them. I originally took on this job due to a blown head gasket. The car seemed to run fine prior to starting this; however, I guess I would never know if it was down a bit on power as I bought it used.

[@gordocarbo]

Your mechanic gave you bad advice...lapping wont fix leaky valves or an engine needing a valve job. It actually makes sealing worse. Id look around for your own machinist for a valve job next time you have it apart.

[@vettepwr23]

@@gordocarbo I spoke to a machinist. Did what he suggested. Turned out great. 20,000 miles later and two trips around the US and truck is running great.

[@Farley1173]

The fingerless gloves had me dying not gonna lie😂

[@zdravkomomci7570]

I like how you do it by hand and that's the correct way going in both directions. Using a drill you can burn up your guides and heat up your stems and recess your seats unneccesary. An engines valves never spin like in a drill

[@paulkimble4548]

Great video as usual.

[@jamestone265]

I’ve had many heads go to the machine shops for value work. For the last 40 years I do all the final assembly and lapping. I also do my own seals after I bought a guide tool from Comp Cams. I have the inside mics and a spring checker to set them one at a time where I want them. I even have purchased valve keepers with different placement of the securing ring. It takes time but at least I know exactly what I have..good video..

[@TheCarPassionChannel]

Even though I'm not a professional, I always try my best to double check the "professionals" work just to put a final set of eyes on it. At the end of the day, it's my investment that's going into the car, never hurts to double check things!

[@cory45x]

looks exactly how it should after grinding. "frosted"

[@shirtz69r]

thanks greg, been thinking about a HP academy course for a while - pulled the trigger after applying your code.

[@TheCarPassionChannel]

The content they offer is top notch, and great for a variety of skill levels. I just recently started taking the courses but have been following their channel for years just loving the 15-20+ minute deep dives into the time attack cars and all the technology they employ.

[@shirtz69r]

@@TheCarPassionChannel agreed. Great resource. Looking forward to feeding the brain and eventually throwing a wrench. Hopefully non Aussie/NZ people can understand the accents!

[@remustrading]

smart that vacum set up. I have a vacum pump and I will copy it. Thanks

[@TonyLiveTV]

Great video! It was your other video that inspired me to build my own tester. I made mine with a $15 vacuum pump & it worked great. In fact I just uploaded a video yesterday on it. In my video I show you how to test without installing your seals. I thought you might be interested.

[@38tech]

I ised to rebuild subbie motors and its very intimidating at first. But once you get it, you got it. Btw....styked is a cross between stoked and psyched. Hahaha

[@OklahomaProudBoys]

Loctite ‘clover’ lapping compound is amazing, it’ll take a couple of their grits but it it worth it.

[@alejonin]

Funny I was doing the exact same thing last week. Exactly step by step. Haha. Good stuff.

[@Asomesauc]

Great video

[@BuddhaOfDarkness]

You really should have more subscribers. Great work.

[@Samiam_ariel]

the tool is genius one thing to think about is in other videos ive seen that when they raise the valve to get more grease on the surface they do it very slowly to not possibly fling a grain of sand into the stem

[@cory45x]

fun fact: valve lapping/grinding compound is the secret to unscrewing stuck screws

[@Pippy1]

Antisieze is basically very final metal ground into a paste, as the metal gets pushed into threads it cleans then and lubes it

[@cory45x]

@@Pippy1 i mean a little dab of it on a screw driver gives it an unbelievable about of grip

[@gfgfdgfdgdgdfg3004]

Could you please do the compression test with the new lapped valves. I would like to know the results now, how much it changed

[@occamsrazor1285]

3:14 These numbers are considered "good enough" for just regular street use. You don't want to see a number lower than 24. If you go crazy with lapping and go from 280 all the way to 1200 grit, you can get 29-30 in/mg and the needle drop time is measure in days and not seconds.

[@shaneeickmeier6213]

There are also different valve lapping grit compounds .

[@Stale_Mahoney]

introducing a bit of moisture helps the suction cup suck on better, think a bit of spit on the suction cup edge and it will loose vacuum slower ;)

[@Str8UpRevving]

When i lapped the valves for my k24 build. I used the drill method, i had severe pitting on the valves /seats. That's a good idea with the block off tool, i'm curious what mine would show now lol.

[@ChromaticVideos]

Another awesome how to Greg! And you always come out with relevant videos when I need them lol. One question, you swapped the valves, but are you doing anything to prevent the intake valve problem that happened? Or will this just become a maintenance job for you?

[@hewbambam]

I think in a previous video he said he was using longer springs. They were slightly lighter but also longer so when they were in the head they had more weight on them. Volvo ones maybe? I don't remember

[@TheCarPassionChannel]

My best guess is that the springs didn't provide enough seat pressure for the combo of boost and RPM, so I've upgraded to a spring with more seat pressure. You can find that lengthy video a few spots back if you care to learn more. But no, I'd rather melt this engine down for scrap over replacing the valves every 13k miles 😅

[@_viy]

Притирка клапанов now I know what this is .. I’m glad you didn’t messed it up. I wonder how many people just through new valves into an old head and make it even worser than it was.

[@golffish7599]

Remember grinding paste came in double ended tub,fine one end coarser the other,initial lap with coarse then finish with fine,want an even matt surface.

[@alonzogodwin3745]

Great work bro! Is it a must that u get the heads shaved after lapping or can they go without if i already have them cleaned? Thanks

[@GotMilkRS13]

Man im getting exited for the dyno session, there needs to be some extra power from better sealing valves. Love the content

[@TheCarPassionChannel]

We'll see, I got almost a half point of extra compression from the shave too. The problem is the compressor on the turbo is at max flow already, so I don't there will be much top end. We'll see!

[@mr.adventure559]

What about ceramic coating the head before installation?

[@FierceMotorworks]

How long did the grinding and cleaning process take? Of course, filming everything adds time, but a ballpark estimate would be helpful for people who might attempt this themselves

[@PcItalian]

Can't wait for new Dyno!

[@PrincetonTV]

first /// wait I mean 3rd. Your tester is excellent. And you can only ever get 29 lbs of vacuum (this is the limit on earth) but compression can be much higher. How do you know if the seal is good at the exhaust/take ports?

[@TheCarPassionChannel]

29.92 is the limit of vacuum, not just on Earth but everywhere :)

[@xavierlipscomb2000]

Did you get the head shaved before lapping? Just wondering before I get my valves founf

[@jimmyfavereau]

You were bold enough to go forward with the valves for the first time, why not sand the head on a sheet of glass or granite? The worst thing that can happen is that you gain very valuable experience... experience can not be bought but has to be lived 🙏🏼

[@TheCarPassionChannel]

Head had a relatively fresh surface already, wasn't needed

[@timocallaghan4408]

the compound doesn't grind down, the coarser compound just gets pushed out leaving the finer grit behind. That's the whole idea

[@TheCarPassionChannel]

Gotcha, so the method I described still works the same way, just in a different way from how it's described on the package. (States: "Grinds down to a 220 grit")

[@GapMiata]

will you try to port and polish that mad lad head? would love to see those gains on the dyno, either way keep it up!!!

[@TheCarPassionChannel]

Mad lad head has massive porting and decking already. I'm excited to see what it does.

[@frankdavidson9675]

an easy way to tell if valves are leaking first take a compression reading then remove plugs add 1 small spoon mtr oil in each plug hole now take a new compression reading if oil helps its the rings are leaking if no help valves are leaking this test is for low comression readings

[@austinwuest2555]

ASMR valve grinding noises, that sound is satisfying 10/10

[@TheCarPassionChannel]

Might just upload 5 minutes of that, to a new channel ASMcaR

[@joelparedes]

MAESTRO !!!!!

[@Victor-wp2be]

While u have the head off for extended amounts of time are you supposed to use any grease around the pistons before u start it up again? Or engine oil?

[@ceerush6284]

Yes you’re supposed to pre lube them I believe

[@TheCarPassionChannel]

Yeah whenever I pull the head I usually just drop an ounce or so of oil in each cylinder and cycle the engine

[@ceerush6284]

@@TheCarPassionChannel hey dude, I know this is random but I swear you need to come to the UK and see some peoples cars you can get a good nbfl with just rusty arches for £1000 all day

[@perjian1697]

You're supposed to use valve lapping paste. Not valve grinding paste. Grinding paste is for reshaping a mating surface. Which should only be done when imperfections are verified. If the surface is smooth you only use lapping paste to clean and mate the surfaces.

[@8145dwerdna]

What if you replaced the exhaust valves and just lapped them like the intake

[@Belialzero]

*Pressure to pull head intensifies*

[@matthewdrake1434]

ALL BOW DOWN TO THE MIATA DAD CRAIG🙌

[@patrickfargie1146]

Have you looked into doing a DIY porting job? The heads have casting flashes that can get drimmeled down as well as the plunge cut where air feeds into the valves.

[@TheCarPassionChannel]

This head has mild porting already, and without a way to actually test what I'm doing, I'm not going to take it any further myself.

[@brub5174]

You got an idea how many hp/torque improvement this could have added?

[@brianfrancis2862]

if avalve gets misked up will it lap right

[@tropicalparsoon]

Awesome video as usual, why are you not removing just a TINY BIT of cylinder head material to deshroud the inlet valves?? The incoming charge hits the back of the valve and wants to continue on that path into the cylinder at quite an extreme angle. It hitting a virtually 90 Deg wall just after the valve seat, at PEAK velocity is a killer. The reason I know this is that I sent my BP5 head off to Blink Motorsport in the UK. They rebuilt it with standard exhaust valves and standard diameter supertech inlet valves with a little bit of bowl work but next to no porting. End result, seriously!! noticeable more power across the board with new (mild) cams and original HLAs and valvetrain. The most usable power is gained at smaller valve lifts as this is the most time of the stroke that you will see. 12mm lift is cool at 12mm but if the cylinder is struggling to pull in charge at 0-10mm then its a pretty meaningless number as it occurs so briefly in the cycle. A tiny bit of headwork around that vertical step will bring massive benefits across the rev range. FUCKING LOVE THE TIME, WORK AND EFFORT THAT YOU PUT IN TO GIVE US THESE VIDEOS!!!! ❤️

[@TheCarPassionChannel]

Man, I really considered de-shrouding the valves while the head was off. Your comment amplifies my regret.

[@Belgarion115]

The saga continues.

[@nissanjon3034]

Key secret: lap until the valve goes quite.

[@john2ndname]

can you give us the gauge pump on where to get it from.

[@TheCarPassionChannel]

In the description there's a link to my video showing how to build the tool itself, all the parts are linked on that video

[@theKmbell]

so early today!!!!

[@davidbarlowjr7583]

Sooo closeee

[@lilmike2710]

You'll want to keep the same valves mated with their respective ports. 🤓

[@fatninja987]

I’m here dad

[@Simpyspec]

Wow, this is so great DIY everything thank you miata dad. you should get a rotary swapped miata lol

[@multishit6664]

LOL ehh depends on your goals and materials really. You cant lap titanium or other exotic valves made for extreme HP or RPM. They form a seal by smashing into the seat the first few minutes of idle.. also a flow bench and CNC 5 angle valve job is light-years ahead of just Hillbilly toothpase grinding surfaces. ALSO if you choose a professional shop they normally check everything and will give you options or warn you if something is out of spec like a valve guide or any other issues the head might have. Its worth the money and it will come home clean ready to rip and be reliable..if you stripped it down and pulled the head you might as well buy once cry once and do it correctly.

[@TheCarPassionChannel]

I mostly agree with everything here, however I wanted to give it a shot and explore another option. The head had great leakdown results and the engine made over 500whp 😃 but yeah typically I just have a machine shop handle it

[@ajsaracina8380]

Well now I'm hype for rotary miata. Don't tease me like this lol

[@oldmanloki]

**rob dahm has entered the chat**

[@xESPplayer500x]

An easier test is blue dye test

[@davo8802]

Use just 2-3 little drops of compound. That was way to much.

[@DeltaOps3]

instructions unclear, choked on valves, they tasted like titanium. next time im giving my valves to the pros to lap up

[@tedanderson463]

I was viewing your valve lapping video..... Did you know that even if you have brand-new valves.... And your valve guides have got slop in them... And the old valves have made an irregular seat...(meaning the width of the seat is not flat.) And also the seat it's not where is supposed to be in orientation...... outermost edge... The seat should be very narrow at the outermost edge... But... There needs to be a thin margin on the outermost edge also... And experienced automotive machinist needs to be present to show all the mistakes that get made so that people do not get lead down the wrong path... Just because you're interested in all these high-tech things and you shown five or ten percent of what somebody needs to know about valve grinding... Should not let anybody have confidence in what they've seen here.... These videos that you wanabe movie stars are trying to make... Is not only a waste of our time but it could be very costly to us... For instance look at the valve... It should show us what you think and where you think that contact point should be... I was waiting for that.... And it never happened....

[@tedanderson463]

You need thousands and thousands of dollars worth of equipment to work on cylinder heads.... And the absolute expertise and knowledge of what types of grinding stones to have and how to dress them properly and when to put hardend seats in and when to put brass valve guides in and when to diagnose this when to diagnose that... You need to know what the application of the engine is being used for.... You need to know how to relieve the ports ... So that you get better flow.... Sometimes the square inches of the hole where the seat is ...is got to be smaller than the port or vice versa.. lapping is only capable of removing a very small amount of stock... And most of the time if you try to lap a new valve in with bad valve guides... And a professional saw that ...you would get literally laughed off the city block... Like I said just because you're interested in doing this does not mean that you're supposed to be making videos of showing people how to do things the wrong way and wasting their time.. if you think you're going to be learning things from your listeners.... And picking our brains and giving you information..... We do not have time to sit and educate you.... You take a college class on automotive rebuild... Or go work in the shop and start out on the end of a broom handle and work your way up.

[@lander917]

4th

[@carsonspies1073]

First

[@alanfoix9911]

It's all man made 😅