I would much rather you say more and go in depth with details than say less and leave me with questions.

Eric, no need to justify your actions you will never make everyone happy. Keep doing what you do. Hell of a job! Thanks for taking time to explain

Many, many years ago, as a neophyte machinist, I finished the exhaust valve guides on my small block a couple of 10ths tighter than normal (as I remember it 50 years later) for "oil control" purposes. Yup! Heads had to come off due to one stuck exhaust valve 25 miles into the first drive. It was a hard lesson learned. You can't cheat the numbers and win. I addressed the problem and all the issues went away, and oil control was never an issue either. The School of Hard Knocks. You keep on telling it like it is. I appreciate the candor.

Screw the haters Eric. All your work and content is much appreciated.

Eric , bless you for your tireless work, helping us make less mistakes, learn more about airflow, cylinder heads, and what NOT to do, and giving us many, many hundreds of hours of your knowledge . Bless you brother, you're the best

Just skip any negative comments, move on, getting upset makes them the winner. Your passionate about what you do great just share and be proud. Thanks for sharing

It's incredible the amount of detail I have learned from this channel

You are right Eric, it's not the heat that caused the valve to stick, it's when it cools down, too tight of clearance and not enough oil running over the valve spring to keep them cooler...

Thanks for all the great tips! I have a daily 454 with Performer RPM heads on it. I built it 18yrs ago and even though I took the new heads apart to clean up ports, check seats, spring height and pressure I never knew to look for this. It’s been a good runner on pump gas and occasionally on e85 to clean things up a bit. Guess it’ll be something to check out when I pull it down in a few years for a refresh:)

Eric,, I have enjoyed your tech descriptions since I first found your channel. Graduate of the school of life here. Worked in Hoosier Parts performance machine shop in Seymour Indiana in 1990 with a guy who really 'got it' about getting fast. He taught me allot in those years, and something you DIDN'T say, but I was waiting for you to say.... "Loose, is FAST!" I was smiling when you alluded to some of the visual clues on the valve out of the customer's head because it is obvious it's been flexing, thus shedding buildup... and anything that is moving that much, IS going to break. Thanks so much for the time you put in to these posts. It reminds me of the best damn times of my young life. Probably starting around 1977 when me and Robert Erwin used to ride our bikes up a driveway in Seffner Florida to watch a local guy who had made a name for himself in racing circles by putting his nitro burner BEHIND his seat and making it work,, [finally].... I still marvel at my luck to have been a boy of 11, standing under the Spanish moss hanging in the trees along the driveway of Don Garlits mom and dad's place, watching a swamp rat fired up and making the switch from gas to nitro. To this day, I am mystified how I could be so lucky to list the places I have been and things I have seen, in person. Your patient description of how these obvious issues compound, to make for trouble, just makes me feel better that in this mad assed world,,, another guy GETS IT. Randy Baker was my mentor at Hoosier Parts,,, and I am now at 32 years from those wonderful days,, I miss the racing world. But your vids are great walks thru the park Sir.

Eric, don't give the haters their 15 seconds of fame. I appreciate the knowledge you hand out for FREE and feel smarter every time I watch your vids. I'm usually in the first ~ 100/200 views. Appreciate all you do.

I love this guy! Eric you're straight out and up front. If people can't appreciate that, then they won't appreciate what you provide to us for FREE! Thanks again.

There are very few people that know what it takes to properly build a motor. It take a lot of time to insure it’s done correctly. Good Job Eric. Keep up the great work.

Years ago, I bought some used performer sbf edelbrock heads. Took them to the machine shop. Alan told me all the guides were too tight. After giving them more clearance, they were good to go!

Thanks for taking the time to explain that Eric. I would have thought nothing of it if that had been my head. Now, I know better. Keep bringing the tech videos, we love them!!!

Thank you! I bought a Chevy 292 builder motor. It broke a pushrod. I’m so grateful for this video! I’m now considering taking my burr to the valve guide, to at least clear the undercut on the 1.6 exhaust valves. 1.4385 from the bottom or 3.48 from the top. It seams like an opportunity to improve the swirl, but “What do I know? I’ve only watched one of your videos on the swirl subject. Then there’s the whole valve seat installed height to the bottom of the spring for its correct installed height. So, I’m going to upgrade to : a. higher temp exhaust seats. (Machine shop) b. I’m 1/2 way on installing 12Bolt Tom’s lumps in the intake runners. c. 1.94 intake valves and springs d. etc

This makes perfect sense. Explains exactly why I broke an exhaust valve on a SBF race engine.

Thanks for the knowledge. Keep up the great work.

Steve morris had a similair deal happen on a recent video. Tom Bailey stuck some vales badly or start up, on motor that has been together for years. Steve's best idea was the guides heat cycled and had shrunk. He was a bit baffled. Have you seen this follow up vid?

Thanks for pointing this out. Now I have another thing to check that I was not aware of.

FREE ENGINE TECH KNOWLEDGE. I LOVE IT

Really appreciate you sharing your knowledge with us FOR FREE , anyone who complains should take a hike!

Hey Eric, Tim here, yea, i dont like undercut exh valves in general, but didnt know HOW bad it cud get, with said undercut....GREAT tech vid, got my juices a flowin.....TY sir!!

Great Video!!! Very informative. Thanx for taking the time to explain everything.

Valves were sticking and clattering when hot! Now it just did it the other morning one time cold. Symptoms now have went away… Thanks for the class Eric. The 4.6 2V was an odd bird to diagnose. Cause it was so intermittent. Thanks for the detailed instructions.

Daily and drag, I always have to ream new stems because they are too tight. I’ve never had a sticking problem, definitely something that shouldn’t be overlooked. Thanks for the videos!

Great information! Do you have problem with ethanol or methanol and lack of lubricant on the valves?

I have seen this before. I always wondered why. Great job showing and explaining it. The visual really lets it sink in.

Some times it internment sticks. Funny part about the 4.6 2V It’s probably the piston hitting the valve. Luckily the hydraulic lash adjuster keeps the valve from bending and losing compression. After changing an old thermostat plus flushing all the old antifreeze goop out the symptoms have gone away. This engine had the original antifreeze and black hoop in the system. Summary The combination of an old sticking thermostat and also shitty coolant was causing just enough heat transfer problems - causing it to clatter when hot too. The hot clatter went away - after flushing and cleaning the cooling system several times. Running straight water for days - letting it boil out the castings. Now it just clattered one time on a colder morning, before the temp gauge came up some. Eric - thanks for the detailed class:) Okies :)

Thanks you just explained the ticking noise (at start up) I experience on 4.2L Ford (Aluminum Head) because the valve guides are too Damn tight from the factory. Thank You for Sharing your knowledge !

I like your rambling... I like even more that you want to delete the clowns that don't appreciate your knowledge. Thanks for the videos Eric

Way back in the late 80's, I had a chevy 1 ton dually with a 454. Towing my Vega to the dragstrip, I wind up racing 2 buddy's in their dualies towing their camaros up a substantial mountain pass! I passed both of them...winning. lol However, when I stopped for fuel, my truck was a 7 cyl.. bent an Exhaust valve!

Thanks for schooling me Eric, knowledge is power,

Thank you very much Eric. Point … I have a stock 4.6 2V that has an intermittent occasional valve clatter… It mostly does it when it’s cold too. It’s an 18 year old engine… Now we know why.. Rusted valve stem

I agree with the more information, you explain your tech very well!!

You did an excellent job with this video

Great video. I want to know why some exhaust guides wear rapidly, Dart Iron heads in particular. I don't understand why they went to the trouble of using pressed in guides when the could have run the valves in the Iron.

I dunno....i personally find this deep dive analysis stuff fascinating......fuck it, bring on the easel and dry erase markers, the overhead projector, etc.......great video. An educated customer is a happy customer.

Appreciate the videos and thr time you spent making them..

Wonder if the guides been replaced in the heads? To have so much stem covered, idk? I do remember watching a guy, not going to say his channel, he’s pissed some people off, but he has had really good info on his channel. He used to say new heads had way too tight off guides in most cases. I remember seeing the promaxx heads has come out for a sbc and I wanted some for my truck bad, and they actually were ok out of the bass by his standards. Which weren’t much probably 😂. Thanks for going into detail so the guys wanting to learn can.

Good info, always learn something from your vids. Good day sir

Excellent video!!! Please talk all you want to so you can explain everything fully Thank you for the video

I bet you were an excellent teacher.

Thank you for the tech tips we appreciate you

Just keep talking sir. I learn something new in every video.

All good Eric! Thank you 🙏 much appreciated!

Thanks for the deep info I have to know more than just this that and the other thing love the information keep it coming 👍

In your experience do the new AFR sbc heads have tight guides. Currently experiencing exhaust valve issues on a set of AFRs. Going to have to bust them down as soon as I get time to see what’s going on.

Thank you for your knowledge and video's USA 🇺🇸

I like your approach

One issue we are seeing with titanium valves is the valve getting stuck in the guide. I wonder if this is an issue with dual fuels or the expansion of three different materials? I checked to see if there were any known reactions between titanium and brass when under high temps and found none. So the problem has to be in the aluminum cooling off too fast and creating a bond between the guide and the valve. The titanium alloy could be the issue as other minerals could be reacting to the methanol or pump gas. I also question the expansion of the valve stem closer to the valve if the valve is open when the engine is turned off could the cooling process cause a lasting bond on the valve stem?

So on 4.6 2V Make sure you change old thermostats. They are restricting - even if they are not fully sticking! Flush out the cooling system really - really well. Cause the exhaust valves will stick in the guide’s intermittent. Loudly too - making you think the front timing chains are coming apart - or you’re losing oil pressure to the top end.

I never thought about the undercut into the guide causing that. Thanx

I appreciate you sharing your knowledge. Physics is much more understandable, when it has a practical application. I would suspect this engine isn't driven regularly, for distances long enough to get up to temp for 25 minutes or more so condensation is more of an issue.

I know you've said you don't do iron, but I wish I could talk you into porting my Iron Duke head, something unique!

Make the videos longer just to spite them.

Good points all. However, my thoughts on the undercut are that if it actually enters the valve guide ( Which it does ) it allows exhaust gasses to accumulate and condense on that short length of the guide, this introducing carbon contamination within the bottom of the guide and thereby contributing to valve binding. Just a theory. Thanks for the great video !! Mark

Hi are you comfortable cutting the ex guide back the.4 inch? needed to expose the entire undercut? Are the edlebrock guide fit for thinner oil? like 5-30 or 5-20? and last does the carbon on the undercut giong up inside the guide also cause the valve to stick?

Thanx Very Informative!!!!👍👍

Great information

Awesome video!

Cool tech, thanks for sharing

I learned some thing new, thank you.

I've never been able to figure out why some engineer decided a relief in the guide itself was a good idea. I've always tried to eliminate it.

Cam question comp cams custom ground small base circle 240/244@50 .608/.614 lift 110 lsa 108icl motor is 440 sbc. If I was to swap cams what should I look at changing.

Thanks for the heads up, no pun intended.

Great information thank you

Eric didnt freely mention the names of the manufacturers who dont practice undercutting. Most prevalent brands im familiar with who dont, John Deere and CaseIH. Kidding aside, good info and enlightening video

Dang cuz I just took some valves out of some profiler heads some of the valves were stuck AF! Put some new valves in slid in easy. Thanks for the info though, new valves no undercut either.

Thanks for the video

Very informative but i got a question for you. If working on a stock rebuild, and finding rust on the same area, you stated you'd just replace them as it creates a failure point resulting in a bent valve. Granted, the head youre working on is a edelbrock performance head, would you still replace the valve in question, or all as a set.

Thanks for the deep explanation and to those that don’t like to hear explanations need to watch golf. If you don’t like it don’t watch it. Keep your negativity to yourself.

I built a 385 snc with a SCAT rotating assembly, internally balanced etc... anyway I chose the AFR 195 Eliminator heads (street) heads. It appears they need off set intake rocker arms. Do you have any experience or input 😊?

Mabe you could help me. Have you heard anyting bad about Clearlake Heads in Clearlake Florida. I have a set of their heads that stuck an exhaust valve. I only went with these new heads because I wanted to avoid the hemi 5.7 valve seat drop issue. Head only have 2000 miles. Anything good or bad would be really really appreciated. Your the best!

Thank you great video I love the channel .

... Great Content !

Great information as usual you’re on it again !

Since it appears to be the norm for undercut stems, there could be a measurement of seat-to-guide distance to specify undercut stem lengths when ordering to address that exact issue. Gambling with that can be catastrophic, and to maybe add to the causes, poor fuel quality, tune and oil consumption would accelerate deposits, too.

I had Edelbrock Victor SBC heads. Fresh engine new heads, was dynoed ok. Went and road raced. Fri ok one 10 lap or so practice session, Saturday two Q sessions and over a sec a lap better than before. 3 races Sunday, first two ran A1. last[main] race went sour. I still finished in the points. Just. Upon examination is had a bent intake valve. Not badly but bent. No obvious marks on the piston [piston to valve was fine] These were Ferrea premium valves. Suggestions? my engine shop had no answers, one new valve and skim all the valves and seats, they were NOT seated very well from Edelbrock. Though still held kero when I CCed the heads. BTW that deposits on the valve is carbon not rust.

Late finding again! Which GMP heads are they (part #)? I've had a pair on my 502 since 1999. I did get them rebuilt with new bronze guides machines for white poly caps, so maybe this issue was eliminated on mine? I am not aware of any issues.

Snuck some psychometrics in there I like it! I haven't thought about the cold valve condensating the water out of the exhaust

Great tech vid. ❤

Are you and other performance/race head builders leaving the exhaust seal off? Is that more common than not?

To expand on this... Many people don't understand that each gallon of fuel burned produces more than a gollon of water. Normally this is in the form of steam from the combustion heat but, as pointed out it will condense out on surfaces that are cooler, under 100C/212f. The second thing is that as a result the exhaust gases have a high level of water vapour nd as the engine cools that vapour WILL condense in the exhaust ports.

Great video! Wouldn’t that undercut to guide location also effectively shorten the guide and make the valve move more with the same clearance compared to more stem to guide length?

with the condensation forming between 2 dissimilar metals should be getting you electrolysis rather than rust. (I think) Maybe you could film the valve damage thru a magnifying glass or zoom in closer on a tripod , more detail less guessing. When you say cold , is that below freezing ? I have neither seen nor heard of this action in Australia , thank you for bringing it to my attention.

Love it man

Thank you

towards the end of the video, you were giving 3 reasons why it had the issue. on #1, you said it couldn't get rid of the heat. Is that because the undercut doesn't touch the guide? I think that is what you were talking about earlier.

Nice tech tip.....

good stuff to think about.

I had this really bad on 2000 acura integra b18 ls engine the build up was way bigger then the one showed. I had bought the car with bad head gasket hence super amount of condensation burn which is what i had assumed cause that build up on the valve three different occasions of the car burning up exhaust valves i said screw this and replaced all valves . I was gonna chalk it up to old sodium valves breaking down but this sounds more of what happened!

Hi Eric, Great content!! Hey it's ok with me if you talk I personally don't know sign language ! How in the hell are you going to explain something if you don't talk???

This may have helped to save me from a stuck exhaust valve on an aircraft. Wouldn’t be fun to be losing altitude on 3 cylinders.

awesome stuff!, engine looks like its very rich, washing bores, looks to be consuming oil

Right on

Interesting information but it makes sense.

Love your information- I feel sometimes you do go too long- I do what mature folk do- Close the video- And Enjoy the next one ! Please Don't block Me !!

Condensation of water occurs when the temperature of the gas (air, exhaust, etc containing water vapor) drops below the "dew point". Combustion of fuel adds water to the exhaust (a lot), raising the dew point temperature. However, I'd bet that the time the exhaust valve spends below the dew point temp, in a running engine, is probably seconds. The temperature of the guide would climb much slower. There are many other compounds present in exhaust that can condense and adhere to the valve stem, they might form a good binder for the also present carbon particles...the undercut prevents this goop from being scraped off by valve guide contact. I wonder how much of it is actually rust...given the above conditions and the fact that exhaust valves are often pretty corrosion resistant alloys. I guess whether or not it is rust, the result is the same, and would not occur if the undercut matched the head like it should. I made the mistake of intentionally sizing guides a little small, thinking I was making it better. On an H-D Sportster. Front exhaust valve stuck open on the test ride. I think the low compression ratio saved me from destruction...only some additional reaming and lost time were needed. Good lesson 30 yrs ago.

Btw. Great video.