Better Engine Building: Clay vs Dial Indicator when Checking Piston to Valve Clearance

Another in our Better Engine Building series. We show you two methods to check for proper piston to valve clearance on your next engine build. Crashing valves into pistons can be a very expensive mistake and here's how to make sure that never happens. Which method is better for you? Clay or a dial indicator?
Here are links to some of the components and tools I used in this video:
Erson Cams & World Products: www.pbm-erson.com
Dial Indicator w/ Magnetic Base: amzn.to/2Sw2TLm
Checking Valvesprings: amzn.to/2WHq5sA
Modeling Clay: amzn.to/3aHvVOP
Note that Horsepower Monster may receive a percentage from products purchased through these links, so thanks in advance for helping out the channel!

[@UnityMotorSportsGarage]

Best video I have ever seen covering PTV... I love your in-the-cylinder camera angle! A picture (in this case Video) is worth a million words!

[@TheHorsepowerMonster]

Thanks for the kind words! And thanks for watching!

[@Highstranger951]

I really enjoyed the in-cylinder cam. Gives a new perspective.

[@Stale_Mahoney]

yeah and i learned a 3 way to see if you got clearance, simply use a camera, i will definitely use this method

[@sawyerbarnes7439]

First video I found that really explain valve clearance

[@bluegrassbassing3790]

Me too

[@HEATHENYT]

That first part of the video was terrifying lol. I'm loving going back through this content, and learning new things about engines.

[@krisztiantkacs]

I prefer to use both. With the dial gauge of course you got precise measurements. And the clay show you where is the closest point, and your valve pockets are on the right position or not.

[@bobhoffman5581]

No such thing as being "too meticulous" when building internal combustion engines, in my opinion. A friend's brother (who is my friend ALSO!) is one of Jack Roush's "ace" employees, a serious engine guy--my friend told me that even his brother (or anyone ELSE in NASCAR! lol) doesn't torque down cylinder heads like I do. Say the final torque value of the head bolts is 65#. First pull is 30# or so--2nd, is 45#--3rd pull, 55#--4th pull, 65#, and a 5th pull, at 65#, to be SURE. Heads with "torque to yield" bolts are a different "animal," but I've even used this method on THOSE heads also--I haven't ever had a "comeback," due to a blown head gasket, and I doubt I ever will. I also use 100 grit sandpaper and a 15" long 2x4, to "deck" the block; not bragging, just stating truth here--you should SEE the deck, after I DO it. Clean, and flat--as I asked my friend regarding our discussion about this--"can you torque down a cylinder head TOO "FLAT," John? His answer? "No, Red, you CAN'T." lol

[@michaelgarrow3239]

I’m a belt and suspenders kind of guy too.

[@trenthari]

Never in my life do I plan on building an engine, but here I am, watching the whole thing

[@furfeelings]

I'm shocked no one is screaming that you scratched the top of the piston with the razor blade. Very nice video!! Thank you!!

[@cletiskroeker3552]

I did notice that. 😮

[@corybeckmann8823]

That’s honestly not the end of the world. I wouldn’t do that, but it’ll still work good enough lol

[@peterchristlieb]

Love your videos Sir. I remember the days where a motor that ran good meant angle milling, fly cutting and plenty of valve train geometry adjustment. What you do is an art, thank you for passing it on to so many.

[@TheHorsepowerMonster]

Thanks!

[@petegeralis7076]

Hopefully videos like this will make people realize why good engine builder cost money!! It’s an art.

[@TheHorsepowerMonster]

Thanks! And you are exactly right. There is a big difference between an engine assembler and an engine builder.

[@sammytkmperformance]

Great video and explanation. In my opinion clay is the best method with aftermarket camshafts and pistons. This helps verify valve radial clearance which is often overlooked. The valves have to be in the correct location to pistons valve reliefs.

[@jkgkjgkijk]

This is good stuff. I've been a muscle car guy my whole life. I had a 70 Barracuda as a kid. The deepest I got into my motor was cam replacement, springs and valve seals. The rest was a mystery. I would pick the brains of other gear heads but never crossed the divide, graduating to full knowledge of how to rework heads, change pistons and crank seals. I had a 318 and put a 484/284 cam in it by using microfiche in the library and a mail order vcr instructional cassette. I was so proud of that. The lopy cam sound pouring out of my cherry bomb headers as a 20 year old kid...man. please keep it up! I would love to learn this stuff. Subscribed❤️

[@TheHorsepowerMonster]

Much thanks!

[@skylerb7103]

Great video! That’s the first time I have understood the methods shown. Keep it up!!

[@TheHorsepowerMonster]

Thanks! Much appreciated!

[@marklowe7431]

It's one thing to be an expert in a given field but you have a really good way of explaining and the camera is done right. New Sub from Australia.

[@TheHorsepowerMonster]

Hey, thanks for the kind words! And thanks for watching

[@LateStartRacingTeam]

Awesome content as usual. I can't believe I didn't think of using an indicator on the valve to check clearance instead of clay!

[@edwardchascsa4191]

Good video to show what is really going on. Its important to know how much room you have around the radius of the valve and that is where clay comes in handy

[@TheHorsepowerMonster]

Thanks! And thanks for watching

[@ktga67ish]

That’s true too! AFR recommend .020” Radio clearance around the valve to be safe.

[@michaelvanparis9236]

I often get sucked down a rabbit hole with KZbin videos. Stumbled across this one. What degree wheel is that? I like it.

[@markwallace5274]

Great videos very informative channel. I really enjoy how you always give alternative methods that work !! I’ve always used the clay method with great success not all engine builders are like this I’ve meet a few that frown or even look down on methods like plastigauge but hey building engines on a budget is just as fun and possible without all the expensive tools 🤷🏼‍♂️Just having a good machine shop you can trust is the most important part

[@firebird70]

Great instructional vid once again, you nailed it, thank you. Just about to start this check on my 412ci pontiac.

[@angelo_giachetti]

Thats how i did my first and only build. I did it for fun. It ran great.

[@stevensheldon9271]

Thanks for the video. Very clear and easy to follow. I'll be looking through more of your vids!

[@oodeeps]

Very well made video. Thanks for making this easy to understand!

[@jjlad5037]

Thank you! That's my next task in my current engine build.

[@mrgoethe]

Thank you for the detailed model clay step by step.

[@TheHorsepowerMonster]

Thanks for watching!

[@rafatrill]

Very good information I'm have to try both methods out on my next build

[@manishgurav3783]

Sir ! i seen all your videos nice job i am a technician from india

[@TheHorsepowerMonster]

Thanks for watching!

[@ShredCulture]

Cylinder cam makes this video gold

[@chancellor9677]

Nice!!..I am re-building an old school 350 block, 69-75, with 186 double hump heads and a 480 lift hydraulic cam for a 56 chevy truck. Needed info on valve clearance. This video was on point for a beginner like myself.

[@ironhorse127]

Outstanding video. Explained in simple term. Easy to understand

[@TheHorsepowerMonster]

Hey, thanks! And thanks for watching

[@dsevenb]

Killer video. Thanks and greets from North Queensland Australia !

[@tonyschiffiler4816]

Got to love that bore camera , both methods i have used in the past., great teacher , thanks.

[@TheHorsepowerMonster]

Much appreciated! Thanks for watching

[@OneDrone]

I don't often make comments but that video was amazing. Cheers mate!

[@TheHorsepowerMonster]

Thanks a lot!

[@user-leapold]

great video! I have to translate and understand all this, since I live in Russia! I like the American approach to engine repair! I have just as clean and also a good instrument! thank you very much!

[@siliconvalleyengineer5875]

excellent demonstration

[@tslr36]

Um dos melhores canais. Conteúdo muito bom. Parabéns pelos videos, sou apaixonado por motores. 🏁

[@PhilipHousel]

Very informative. Thank you for teaching me something new.

[@TheHorsepowerMonster]

Thanks for the great feedback and thanks for watching!

[@davidvonanderseck8649]

Man I love your tec. Thanks so much. These are the things that guys don't want to tell you. ESP my machinist. Such a big secret

[@TheHorsepowerMonster]

Thanks! And thanks for watching!

[@ronb113]

Gonna be doing this soon to see how thin I can go on my head gasket. Great video!

[@TheHorsepowerMonster]

Thanks!

[@BBBILLY86]

Good video. Enjoyed the inside motor parts.

[@TheHorsepowerMonster]

Thanks a lot! And thanks for watching

[@screamin4402]

Awesome videos man, keep up the good work!

[@TheHorsepowerMonster]

Thanks!

[@elonmust7470]

Wow this video is outstanding! Thanks!

[@TheDrAkira]

Thanks man! Really easy to understand!

[@SJR_Media_Group]

Very useful information... even if a person is not doing his own build, just knowing how to measure this super critical clearance is good. You can ask your builder questions based on this knowledge. Putting a Titanium Valve through a Titanium Piston due to clearance issues should have been measured long before tightening bolts. Oh yeah, that would be a costly mistake - ouch.

[@donovanpiper320]

Amazing video, thanks! This answers so many questions.

[@TheHorsepowerMonster]

Thanks for watching!

[@nasreddineberkouia1547]

Thanks a lot well explained both methods I really enjoyed it.

[@FixTechStuff]

You make it look easy. 👍🏼

[@savvy2807]

Good idea for the dial indicator stand.

[@TheHorsepowerMonster]

Thanks!

[@RANDOMNATION907]

pfff . . . . subed. That was the first video of yours that I've watched and it was just about perfect. Looking forward to more.

[@eduardomargutti]

I was tripping when I saw this guy compressing the valve spring by hand 😳😳😳 then I looked at the springs 😂😂😂😂😂😂

[@ZXDF51]

Excellent video on explaining how to do this. 👍

[@TheHorsepowerMonster]

Hey, thanks a lot! And thanks for watching

[@oscarpuente2029]

outstanding! video very informative.

[@JohnClutch1]

Great video. Thanks!

[@musskeeterbump]

☺️ Me havin a moment of clarity watching this video , all my adult life trying to see this process ( it is a process ) in this prospective . This is cool 😎 😊

[@wangchun6784]

Thank you kindly for sharing

[@sahalin12345]

Very informative! Thank you!

[@TheHorsepowerMonster]

Thanks for watching!

[@robinstan5810]

the cylinder camera was amazing... i wanna see more like that

[@TheHorsepowerMonster]

Thanks!

[@thetinguy]

Sick borescope cam.

[@TheHorsepowerMonster]

Thanks!

[@corvettefever360]

I use both, dial indicator is for precise measurements, but..... I only use the clay for a visual determination in the valve alignment to the piston, or where exactly the valve lands to a specific area on the piston. This is great "guide tool" for determining possible fly cuts, additional fly cutting, etc, & without removing too much material from an area of the piston top where it's not necessary. For instance, i have also had needed clearance with the dial indicator, & been able to determine that the valve imprint in the clay is too thin or close in some areas than others. Especially with all the variables, as different manufacturers designs & specs, who decked or milled the block & /or heads, not to mention how they were done. Where there mistakes for the factory, the machinist, a customer brings in parts from who knows where, are the valve guides out- toleranced, considerable piston rock, expansion rate of specific metal combinations, etc etc etc. The list goes on. So the clay can give you a clear visual picture of where, even tho in "cleared" with dial indicator, the valve may still be too close to specific areas of the piston. Especially with higher performance, tight clearanced engines, & then also considering some of the variables I mentioned above. And this has & does happen. Ironically so many frown upon the clay method, yet many real experienced builders use it, such as myself, & for the same reasons too. I use it as a guide tool, & not for the precise measurements, for those I use the dial/digital calipers. Unfortunately there are too many inconsistencies with clay, in its consistency, how it was made, mixed, temperatures, losses of moisture in parts of it that aren't maybe noticed, & then how it reacts to the pressure of being "pressed or squished ". I have taken the same measurement a few times with clay & had different results. And when measurements within thousands of an inch are important, if not determental, then there can not be any inconsistencies.

[@timewarpvideo6244]

More great stuff!

[@frankdatank7751]

What do you think about stainless steel exhausts valves vs steel? Thanks This is the best video on how to use a degree device ive seen yet!!

[@tdawglp]

Love the video! Miss seeing you up at KT's. Hope you're good man 👍

[@TheHorsepowerMonster]

Hey, it's a voice from the past! I am, hope you are too! I miss the old days doing stories at KT's, they were fun.

[@tdawglp]

@@TheHorsepowerMonster oh yeah, it was good times . just to clarify , it's Thomas Purser. Keep up the good work man! Follow all your stuff 👍

[@TheHorsepowerMonster]

Yeah, I clicked on your name and watched the video where you were helping someone get his mustang engine fired up.

[@rnappi]

Great video 👍

[@TheHorsepowerMonster]

Thanks!

[@frankbiz]

👍🏻 Great explanation and close up video in the cylinder. Was there vertical scoring of the cylinder wall?

[@mrmedium7984]

This is bible level of information. If you engine build or want to engine build, you better save or download this content.

[@izzycamaro]

Thanks, that was just what I needet to lernd for when I install the heads on my sbc chevy

[@TheHorsepowerMonster]

Awesome!

[@jacktaylor9129]

Honestly learned something new today an the clay method is simple an very effective which is something i like

[@TheHorsepowerMonster]

Thanks! Glad the video was helpful

[@AmirPomen]

Im using both... 1-dial to measure how much the actual clearance 10degre btdc on exhaust and 10degree atdc for intake clearance 2-clay for actual valve pocket marking to do pocket cut if needed...

[@StephenBrewer89]

Great video

[@TheHorsepowerMonster]

Hey thanks! And thanks for watching!

[@hotrodray6802]

👍👍 Really like the boroscope.👍 I'm suprized that you did not mention valve edge clearance. Great explanation. Thanks. 😁😎😎🇺🇸

[@BorchOka]

Thank you! 👍 👍 👍

[@tomvo96]

Awesome video! Really appreciate the effort that went into making the explanations clear and concise. One question, though, with the indicator method: How does one find the timing BTDC/ATDC when the valves will be closest to the piston? Thanks!

[@TheHorsepowerMonster]

Good question. Check out my video "Better Engine Building: The Easy Way to Degree in Your Cam" (kzbin.info/www/bejne/bX-yamqEg7Wnq7M) for how to do that. I did that one first because parts of it are necessary when checking piston-to-valve clearance. Thanks for watching!

[@AngryBengry]

Really enjoyed this Thx

[@TheHorsepowerMonster]

Awesome! Thanks for watching!

[@kas1nova1]

Love tips like these..

[@TheHorsepowerMonster]

Thanks!

[@righteousman8488]

good job sir

[@chrisgarrett6820]

I use clay on every engine I build. The fault with the dial indicator you don't get a visual on the valve clearance around the brow of the valve relief. This is very critical if going to larger valves or if the head has ever been repaired. We have a piston vise and have had to move valve pockets back and side to side to gain clearance on custom applications. The indicator method would never show if you didn't have enough clearance on the perimeter of the valve relief. I'd say for anyone doing basic combinations the indicator would be okay but I'd never rely on that for custom applications.

[@themanthemyththelegend1392]

Nice score on the piston, depending on the application that is going to be a sharp edge causing a hot spot.

[@thatguyispro]

My thoughts exactly 😬😬

[@gearhead7896]

Great video and great camera work inside the combustion chamber. Quick question; I want to measure total valve clearance before I buy/install a cam and work backwards. Can this be done to get close to a cam I can run? I know there are multiple factors (duration and lobe separation angle) but lift would be the most direct.

[@marklowe7431]

Another well explained video. Cheers. The in cylinder camera was gold.

[@mikef-gi2dg]

That was an easy to understand demonstration. Some of the written descriptions are complicated at best. Great job. But there is one thing I don't understand, why not check clearance when piston is at top? That is as close to the valve as it can get before the valve even opens.I know there is a good reason, I just can't see it. I have only built very mild street stuff, is there a point where this method is mandatory? The videos are very good.

[@TheHorsepowerMonster]

Thanks! I'm glad it was helpful. You can certainly check clearance at TDC, but at that point both valves should be closed. What a lot of people don't realize is that the valves actually move faster than the piston. So with agressive cams for a performance engine, the valve can be moved so fast--either opening for the intake or waiting until the absolute last second to close for the exhaust--it puts it into contact with the engine. Hope that helps.

[@Texasknowhow]

Another nice video. I also enjoyed the in-cylinder video - was that looking through the spark plug hole?

[@TheHorsepowerMonster]

Yes, using a cheap endoscopic camera I pickup up off Amazon. I've been looking for a high-def version but can't find one. Thanks for watching

[@kirangan6366]

awesome, thankyou sir.. 🙏

[@TheHorsepowerMonster]

Most welcome

[@jimmattingly4234]

Great video only thing I like to add if you are degreeing. Cam much it needs to be if moving cl much makes a difference

[@iamnoone.]

Your camera person was brave to stay inside the cylinder while you turned the engine over.

[@kentharveynunez7800]

💪🏿💪🏿💪🏿 learned a lot

[@ronringler4286]

Good video

[@TheHorsepowerMonster]

Thanks!

[@hectordelgado3258]

For this to be accurate do you have to make sure you’re squared to the valve? If it’s a little diagonal won’t your readings be off? In my head I can’t tell if the reading will be larger or smaller than the true value

[@markjanetti9501]

Nice video, what brand that degree wheel

[@nick4506]

is the tootsie roll method real? basically a tootsie roll in place of the clay. comes with wax paper on it so you don't have to worry about it sticking and also you can pull it out and measure with the calipers more accurately. but now that I think about it its a bit stiffer so you may have issues with collapsing lifters. or is there some other downsides I'm not seeing.

[@johncholmes643]

Generally, I use zero lash to accommodate for false valve train adjustment. Ya just never know....

[@charlespetersonii6989]

Interesting. I think I'll use your method now 👍

[@MissionRestomod]

That’s a good “worst case scenario” way to build it. Especially for beginners like me! 😆 some forged pistons swell up and out so it can’t hurt, even with perfect timing!

[@thisisyourcaptainspeaking2259]

Good idea.

[@ReubenHorner]

@@MissionRestomod if the block is alloy then as the engine heats up the p2v will get larger

[@ChristopherJones16]

can someone tell me what zero lash is? I know theres caps called lash caps that go on top of the valve but didnt see them here.. so what exactly is the lash?

[@TerryClarkAccordioncrazy]

How do you know if you are getting valve bounce or float with aggressive cams?

[@akramdastager45]

I have a Honda k20 engine. I have 1mm oversized dished valves on the intake and I have stock size flat faced valves on exhaust side. Is this a good set up?

[@Supanova70]

If i have steel heads to i even need spring locators?.490 lift cam. just use shims to set valve installed height and be done.?

[@iniseptember3075]

Thankyou so much..

[@TheHorsepowerMonster]

Thanks! Hope it was helpful

[@dadfood3504]

I think its worth investing in the tools to do it right

[@JoseLopez-ep9jl]

Mr. You know the part number of the housing gasket between block and transmission housing?

[@JorgeTheilacker]

The 10 degrees BTDC and ATDC for the exhaust and intake valves are a rule of Thumb? The exact angle to measure It are not dependent of camshaft diagram and timing in use? Seems to me that clay is more on the safety side...

[@YellowstreakBison]

what if there is no clearance, how do you detect that? is the only way by feeling the resistance while trying to spin the engine by hand?

[@ChiefCabioch]

Clay is perfectly satisfactory, it isn't springy, what ever it measures is accurate, I've used both, and while the dial indicator method looks better, the window of piston travel and valve interference is a narrow area, and could be missed, but rolling the crank through several revolutions will give a very accurate reading, and clay will also show if the valve pocket is cut at the same angle as the valve...

[@Moparmaga-1]

I thought I was subscribed last year. Dunny

[@sequoiaohz]

Do you always measure at 10 degrees before and after TDC ? Also for example with a Ford FE engine ?

[@177SCmaro]

I'm a 34 year old man and I still play with play-doh I bought at Walmart.

[@joesmith306]

The clay method is best, it also gives the valve pockets relation to the valve to check for shrouding.