The Only Video You'll Ever Need to Know how 4 Stroke Engine Valving & Timing Works
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- čas přidán 23. 06. 2023
- Master Engine Valve Clearance adjustment settings and valve timing with this Valve Clearance Explained video. A Comprehensive Beginner's Guide to Engine Performance.
Any ambitious engine enthusiast must understand valve clearances. We will study the subject of valve clearances, also known as tappets, and the method of adjusting them in this thorough beginner's guide. We'll also explain how the crankshaft's rotation interacts with the movement of the rocker arms, pushrods, cam followers, and cam lobes in order to maintain proper engine operation. Prepare to increase your knowledge and advance your engine competence!
Why are valve clearances important and what are valve clearances?
Valve clearances are defined, along with the role they play in engine performance.
Investigating how improper valve clearances affect how an engine operates.
Realising the importance of valve clearances in producing the best possible power, efficiency, and durability.
Adjusting Valve Clearance: A Step-by-Step Guide
Tools and equipment needed to alter valve clearance.
determining your engine's unique valve clearance requirements.
Detailed guidelines on how to accurately and correctly modify valve clearances.
Techniques and advice for ensuring accurate adjustment and avoiding typical errors.
Crankshaft, Cam Lobes, Cam Followers, Pushrods, and Rocker Arms: The Dynamics of Engine Function
Separating the crankshaft and camshaft's connection.
investigating the role of cam lobes and how they work with cam followers.
recognising the function of pushrods and how they relate to rocker arms.
investigating the transfer of motion from rocker arms to valve opening and closing.
Optimal engine performance is achieved by coordinating valve clearances.
linking the camshaft profiles and engine designs to the valve clearances.
valve clearances and the effects of valve lift, duration, and overlap.
Adjusting valve clearances to meet performance requirements and engine upgrades.
Suggestions for preserving valve clearances over time and in various operating environments.
You can maximise the performance of your engine by mastering valve clearances and understanding how the crankshaft, cam lobes, cam followers, pushrods, and rocker arms interact. You are prepared to go off on a path of accuracy, performance, and in-depth comprehension of engine mechanics with the help of this beginner's handbook as your trusted resource. Prepare to increase your engine knowledge and release all of your passion!
For an internal combustion engine to run and operate at its best, proper valve timing must be maintained. The perfect synchronisation of the intake and exhaust valves' opening and closing with the motion of the engine's pistons is referred to as valve timing. For optimal fuel combustion, power production, and engine longevity, proper valve timing is crucial. The following factors are crucial for establishing proper valve timing on an engine.
Camshaft and Crankshaft Synchronisation: The synchronisation of the camshaft and crankshaft is the main factor in controlling valve timing. At particular times during the engine's cycle, the camshaft's lobes press on the valve lifters or followers to open and close the valves. In contrast, the pistons are raised and lowered by the rotation of the crankshaft. It's crucial that these two parts are properly aligned.
Timing Marks: The crankshaft and camshaft gears or pulleys of most engines are marked with timing marks. These markers line up when the number one cylinder's compression stroke is at top dead centre (TDC) for the engine. These marks must be properly aligned to guarantee that the valves open and close in accordance with the movement of the piston.
Timing Belt or Chain: To link the camshaft and crankshaft, many contemporary engines employ a timing belt or timing chain. To maintain precise valve timing, these parts must be in good condition and properly tensioned. Timing problems and probable engine damage might result from not replacing timing belts according to the specified schedule.
Engine manufacturers give valve timing diagrams that outline the precise timing of each valve's opening and closing in relation to the position of the piston and the crankshaft's rotation. When determining valve timing, these diagrams are an essential resource.
Variable Valve Timing (VVT): Some engines have systems that allow them to adjust the timing of the valves in response to changes in engine speed and load. These systems improve emissions control, fuel efficiency, and performance. The proper operation of VVT components must be guaranteed.
Many thanks
Craig (Owner and Creator of The Repair Specialist Channel)
#ValveAdjustment
#TappetClearance
#EngineMaintenance
#DIYMechanic
#BeginnersGuide
#EngineTuning
#AutomotiveTips
#ValveClearanceAdjustment
#EnginePerformance
#TappetSetting
#ValveMaintenance
#EngineRepair
#MechanicalSkills
#CarMaintenance
#EngineFunction
#valve timing
#set tappets - Auta a dopravní prostředky
Hi guys I just wanted to Introduce to you my other Channel "Kirkman's Academy" - which i'm just getting started. It's a go-to channel for simple explanations for hard to grasp subjects such as physics, maths and chemistry etc. Here is the link: www.youtube.com/@kirkmansacademy/videos . Thank you so much for looking, and if these topics interest you then I hope to see you the there. Many thanks indeed. Craig 😊👍
I just understood something I haven't understood for like 29 years. Awesome video
This was the most comprehensive explanation of how valve clearance works. Much appreciated the effort put in to explain for a newbie like myself. Instant subscriber
Great explanation and the cut-away motor makes it so much easier for visual learners to see what's happening, when and why. Very well done.
I really appreciate your kind feedback. Craig 👍👍👍
This the first time I have learnt how an engine works clearly. Thanks for clearing my confusion. Explained professionally.
Thank you so much for your very kind and motivating feedback. I really appreciate it. Craig 👍👍👍
This is a superb video. I've not seen such good - concise, yet thorough - training since I was learning to be an aircraft technician in the Royal Air Force.
Thank you very much, God bless, and let's hope the algorithm pushes this out to many more people. Chris 👍
Mate, many thanks. Timing has always been intimidating for me. This definitely helps alleviate that fear a bit.
What a great teacher you're sir keep it up
You are a very good teacher.
So insightful!❤
I am an Electrical Technologist, and this video has been very helpful in understanding engines. THANKS!
Great video, gf was asking questions that i couldn't explain very well. Your concise and thorough video (and that cutaway engine) made everything crystal clear. Thank u kindly sir! Instant sub!
Awesome, thank you so much. Craig 👍👍👍
Brilliant video , I finally now understand how it all works, thanks for posting 😊
Precisely explained.
Thank you so much! Craig 👍
Very easy to follow!! Thank you for taking the time to make this video.
Awesome video. Great job explaining valve lash!
Thank you for such a great explanation of adjusting valves! Well done!!
Your video is very helpful for a novice and very much appreciated.
Very thorough. Thank you!
Great video. Thanks!
Excellent video, thank you!
Best one, I shall recommend to anyone need it.
Thank you for the post.
I would give you 100%
Brilliant explanation. It cannot be made any better.
Thank you for sharing great video 👍👍👍👍
I had a good general idea of how the valve terrain operates, but after watching your video It's clear to me. Great video and very educational. Thanks, mate.
This is a wonderful. So clear and concise. Very academic in presentation and explanation.
That was one of the best explanations I've ever heard. Brilliant. Thanks for sharing.
Wow, thanks!
Excellent video!!
This was really brilliant, excellent job!
Thank you very much! I really appreciate it. Craig 👍👍
Probably the only gold star explanation of valve clearances on CZcams. Thank you for this content, liked and subscribed👌
Thank you for kind and motivating feedback. I really appreciate it. Craig 👍👍👍
Great illustration👍
Just want to say that as your video title states- this is the only video I'll ever need to learn 4 stroke tappet clearance. 100% TRUE!!!!! After watching this video all my doubts and queries are cleared and the explaination with this model , amazing work man. Just AMAZING!!!!! I do hope you make such videos in future as well. And i request everyone to just watch this 11 min video with patience and all your queries will go away.
Thank you again for making such simple video explaination.
Wow. Thank you so much. I really appreciate your kind and very encouraging comment. Craig 👍👍👍
Thanks for sharing your knowledge! Great video I’m working on a dead 4 wheeler think it jumped time so I’ve been playing with the timing and was getting tdc but wasn’t sure it was on the compression stroke now I do thank you!
This is a great explanation.
Really detailed explenation... You forgot to say that there is a mark for top dead center on almost every engine...
Great tuition Video, Keep up the good work
thank u sir was waiting for this ,you made it so easy to learn
Muy buena esplicacion gracias Good explanation thanks
Thank you very much for your kind feedback. I really appreciate it. Craig 👍👍👍
Very well illustrated, ❤❤❤😊
The best explanation so far.. Thanks..
Underrated channel. Great explanation for a newie home mechanic to watch, learn, and understand! Thanks, Craig!
Awesome! Thank you! Craig
Craig another outstanding video with an excellent overview of how the internal 4 stroke engine works. Great job👍Artie
Thank you Artie. I alway appreciate your kind feedback. Craig 👍👍
Just the right amount of information and an outstanding format for learning 👍
Thank so much. I really appreciate your kind feedback. Craig 👍👍👍
It's very useful tips thank u
Wow thank you so much very interesting and educational 👍
You are very welcome Thank you
Hi Craig, best explanation I've seen!
Wow. Thank you so much. Craig 👍👍
purfect explained and showed
Thank you so much. Craig
By far the best explanation I have seen. Thank you very much 😊
Thank you so much for your generous words! 😄 I'm absolutely delighted to hear that you found my explanation on 4-stroke valving to be the best you've come across. Your appreciation means a lot to me, and I'm here to provide more insights and explanations whenever you need them. Keep that curiosity alive, and I'm grateful for your support! Craig
Top video mate 👍
Mr good simple description
Probably the best ever vid on valves?
Wow. Thanks so much for that awesome comment. Craig
There aren't many folks like you mate, just aren't. This is a class A rating masterpiece. I won't say much let me enjoy your thread of videos.
Hishia, Africa - Zimbabwe.
Wow. Thank you for the awesome feedback. I really appreciate it. Craig 👍👍👍
If the exhaust is too loose it will be difficult to start, the comp release won't hold the valve open enough. The compression release is a small tab on the camshaft that holds the ex valve open just a small bit to allow easy starting, when the RPMs reach a certain speed the tab slings out of the way and allows the engine to operate normally, so if the gap is too much the tab will only take up the gap and not hold the valve open.
Great information.
I'd like to see how you do valve job too.
Great suggestion!
Thank you so much for your crystal clear explanations, I have learned so much from your videos. Keep up the great work:)
You're very welcome! Thank you for your very kind feedback. Craig
You're the best teacher
Wow, thank you so much. Craig
Excellent teaching!!
Thank you so much for your kind comment. I really appreciate it. Is your engine a small single cylinder like this? and could you tell me of any parts of the video that needed more clarification? I really appreciate your honest comments. Thanks again. Craig
Excellent video
Thank you very much!
Fantastic explanation.
Thank you. I really appreciate it. Craig 👍
Very well done video, now i understand how to set my lawn tractor valve clearance... Keep up the good video educational work !!!
Thank you so much for your kind feedback. I’m really pleased you can now set your value clearances. Craig
Just the video I wanted to see
Wow the title of this video is true thanks for making the video
Beautiful matey,Absolutely Terrific!,good onya cob,thank you!
Thank you kindly, I really appreciate it. Craig
Great job! another great video for , all of us to view. I only wish I would have had those video's when I was 14-15 yrs & just getting into small engines, those video's & your information would have made A World of help for me. Keep them coming.
Thank you very much! I really appreciate your support. Craig 👍👍
This is an amazing video. I'm very visual and learning how it all works together while trying to adjust my Ural valves is priceless. Thank you for explaining it so eloquently, easy to understand. Cheers!
Excellent explanation, very helpful. I just subscribed for more content. Thank you.
Awesome, thank you do much. I really appreciate it. Craig
Thanks Craig.
Very welcome
Thank you.
Big help
Excellent teaching moment. :)
Thank you 👍👍👍
Well explained 👍👍👍👍
Thank you 😃
Excellent 👍👍👍👍👍
Many many thanks
Wow this is a fantastic video... So much information.. ta mate
Thanks mate. I always appreciate your kind feedback. 👍👍
Perfect
Thanks 👍
No problem 👍
That made my morning coffee!!!
Awesome 👍👍👍
Hi! I've been following your channel for a few years now. I do small engine repair work in Lithuania. I'm learning from my father who is an experienced repair specialist. I rely on your videos for the theoretical part of the job as many situations I encounter seem like magic if explained with no theory and only by experience and observations. I couldn't wrap my head around the saying that valves 'burn out' if the clearances are too tight. I have observed it, but couldn't figure out the cause. The same goes for the problems explained in your ignition coil videos. Thank you!
Have you got experience working on ridable mowers and their electrical components? I still struggle with troubleshooting that
Thank you from this newbe
What a great detailed explanation of what too loose and too tight valve gap adjustments do! I knew they needed to both be correct, but now I know why and the consequences. For your adjustment procedure, I know this was just for explanation, but you didn't mention loosening the adjustment locking screws before adjustment, tightening them after and double checking that the adjustment did not alter from tightening them enough to make a difference. Potentially, anyone who sees this for the first time could do it wrong and have an issue shortly after. You know I love your work, but I just wanted to point that out, as I'm sure others have as well. I hope you don't get bombarded too badly over it. Mine is meant as a friendly comment. Thanks for the detailed explanation, Mr. Craig. Always so informative, detailed and the arrows really help.
Thank you so much. I always appreciate your kind feedback. Craig 👍👍
Good vedio send more
Great video and explanation; thank you very much. I tried to set the valves on my 250 (OHV motor) and there was no way I could loosen the valve adjusting locking nuts.. They just would not loosen... I was afraid I might strip them... The motor was on the F timing mark and both valves were closed, but even then I could not feel any "looseness" I`ve got no idea why? 😕
Thanks for your teaching. Had no idea how it works. Question: is having the piston to its highest position is what matters to start adjustment. Correct if wrong. Again thanks and Gob Bless.
very good
Thank you! Cheers!
Great job my friend. I have a 22 year old Peugeot 206 1.4i which has had a persistent misfire (P0200 and P0300) for several months (I have not driven it), I have replaced the sparks, the fuel injectors, the coil pack, the knock sensor, the camshaft sensor, done compression tests, tested the continuity and voltages across the ignition circuit, I have just replace the timing and drive belts (they were old anyway) and all that I have left is the valve clearances...I do get an occasional 'ping' during a misfire so I'm pretty confident it's the valves after watching this video....
I should add the P0200 was fixed by replacing the knock sensor...... it had cracked wide open.... was the original 2001 sensor.
wao what an explanation
Great video!!! Now do I set the clearance on both valves on the compression stroke,? Thanks again!!!
Thank you so much I really appreciate it. Craig
Excellent. And if the valve gaps are correct and there is still poor compression it means that you have other problems, such as damage to the valves as you describe. (Hope that's not so in my case, but I guess you may have another video covering that :) )
Good lesson, but I wonder how to find the TDC in a multicylinder diesel engine fitted with prechambers and not externally marked with some indication.
The video is very interesting. In your experience, is it possible that all 6 rocker arms on the right cylinder bank break and not a single valve is bent? Thank you for your feedback and best regards from Austria.
That was a very good instruction. I would like to add, because I got fooled once, that Briggs and Stratton Vanguard engines in the US call for an indicator stick, and they specify 1/4”
lower after TDC on compression as the set point. I’m not sure why, but that’s their spec.
Great tip!
I use a multimeter with a “frequency” function to set idle speed. Put an antenna on the positive input terminal, place the antenna just close enough to the spark plug wire to get a reading, not too close.
i.e: 1000 RPM= 16 2/3 RPS, or 17 hertz (rounded up). This assumes a lost spark system, whereas a distributor spark would be half that. Ok last Heloise Hint, don’t want to be a pest, but just to give back a token to repay all I have gleaned from watching your videos.
Thank you! Great explanation indeed. One question though: is my understanding correct that during a one full cycle the magnet on the flywheel passes by ignition coil twice? If so it appears to me that we get on spark at the end of compression and one more on exhaust? I'm not very sure how that works and everybody seems to say there is just one spark, and that is reasonably.
Thank you for kind comment. I really appreciate it. Secondly, you are absolutely correct about the spark firing twice for a full revolution of all four of the engines strokes on these small single cylinder Engines. Other people who have told you they do not fire on the exhaust stroke are confusing themselves with larger engine that use a battery to charge the sparking system to generate the spark. These systems have more advanced spark timing. These small lawnmower engines, however, are not that advanced.
They do not use a batter to charge the sparking system. Instead they use the magnet on the flywheel and the ignition coil pack. Every time the magnet passes the coil pack it will generate a spark, as you correctly said. This means that after the magnet has passed on the compression/power stroke, it's one full turn from this will indeed be the exhaust stroke, which is where the spark plug fires again.
Why does it do this? Well simply because of the design of the magnets positioning on the flywheel making for a simple and easy functioning sparking system function. Of course, the side effect of this system when it was developed was that the spark plug would fire on the exhaust stroke as well, but this was to NO detriment to the engines function what so ever.
On other larger engine types where the spark plug fires on the exhaust stroke, it is known a wasted spark system. Take a google search and search for this: Wasted Spark System.
I hope this helps
Craig
Ive always tried to explain to people the value of proper clearance as valve timing, especially those owning trucks
Great video Craig. I have always wondered why they went to the overhead valves. These engines having more parts seem to have more problems. I have a Techumse flat head on my 1974 Sears Rototiller and I run it every year 5 or 6 times, drain the gas from the carb, and put it away. The flat head seems like a more reliable engine. If you would, compare the flat head to your model here and note the differences between engines. Thanks
First of all, thank you for your kind feedback. I really appreciate it. And yes, you have given me a very good idea for a near future vid. I do have a flat engine somewhere in my pile of engines. I will pick out one and do a vid on the comparison, just as you said. I do have a list of a few vids to get through first but I will get round to then. Thanks again. Craig 👍👍👍
I love my flatheads, FLATHEADS FOREVER. But the OHV engine is better in practically every way possibe. Yes it sucks to admit it but it is no contest. Unfortunalty
Excellent video. I wonder if it is safe to use a rope to lock flywheel of lawn mower so that I can remove nut? I saw in one video guy said it is not safe to use piston stop tool on large engines like lawn mowers. Some guys using rope, but some saying could be issues with valves. I have a feeling it should be safe to put a rope in the middle of compression cycle as the both valves will be closed. Am I right?
Hi. In my opinion, using a rope to lock the flywheel of a lawnmower can be a useful method for preventing the engine from rotating while you work on it. However, it's important to use this method correctly to ensure safety and prevent any damage to the engine.
Your understanding is correct: When you insert a rope into the spark plug hole and position the piston in the middle of the compression stroke, both valves should be closed. This is a safe position to lock the engine because it prevents any potential interference between the valves and the piston. It's a common practice among mechanics and DIYers for performing maintenance tasks like removing the blade or working on the crankshaft nut.
The key is to ensure that the rope is inserted far enough into the cylinder to provide adequate resistance when you turn the crankshaft nut. This resistance effectively "locks" the engine, preventing it from turning while you apply force to loosen or tighten the nut.
Using a piston stop tool is another method, but as you mentioned, it may not be suitable for larger engines like lawnmowers. Using a rope is a practical alternative, and as long as you follow the correct procedures and ensure that the rope is properly inserted to stop the piston, it can be a safe and effective way to work on your lawnmower engine.
Always exercise caution and follow safety guidelines when working on any machinery, and consult your lawnmower's manual for specific recommendations related to maintenance and repair procedures.
Thanks
Craig
I have a highly modified engine (+13mm bore size, 2 valves per cylinder to 4 valves sohc) the manufacturer specs for valve clearances does not work anymore ,how do i figure out how much clearance should i need?
How can you til if the valves should be offset when manual shows either or or doesn't say?
Like .004 to .008 intake & .006-.008 exhaust. Or mfg manual says .004-.006 inch on both.
But doesn't say if it should be offset for a 208cc generator.
I only hear offset the valves from the technicians by example of operation.
So offset or not?
if youve got a range [ 0.022" - 0.032"] for the valve lash and have got cold start misfires. are the valves too tight too lose? I've got a G.D.I. engine 2016 only 30k miles with cold start misfires? do you use the looser end of the spec to adjust or shoot for the middle of the spec?
Backfire is exhausted is too tight? That's been my experience.
That was an amazingly detailed video. I haven’t found it explained better anywhere else. Curious if you think that setting an intake valve .01mm over spec would cause an issue? I know some engines give a range, but my particular one on a motorcycle does not. I had it set to spec and it seems to have tightened prematurely after only 1500 miles causing performance issues. I don’t know if this is a feature of a new engine, or if I should set it slightly looser to extend the time between service. It calls for .08mm and I’m thinking of setting to .09 next time. There isn’t a lot of information about things like this. I would greatly appreciate your or anyone else’s opinion. Thanks.
Hi. First of all, thank you for your really kind and thoughtful feedback. I really appreciate it. Now to answer your question, in my opinion of course, . When it comes to valve clearances, precision is key, as even a small deviation can affect the performance of your engine. Setting your intake valve clearance at 0.01mm over the specified measurement may seem minor, but it can indeed have an impact. However, valves can tighten over time, especially in new engines as they go through a break-in period. This tightening is often due to the valve and seat wearing in and finding their fit, which can cause the clearances to reduce. If you've experienced a premature tightening after only 1500 miles, this could well be a sign of normal settling.
Setting the valve clearance to 0.09mm, a slight increase from the specified 0.08mm, could provide a buffer against this premature tightening. However, just be mindful of the potential for increased wear over time, which could lead to a larger than intended clearance if it's set looser from the start.
If you feel that you had no issues though and so are comfortable carrying on setting your valves this way then that's absolutely your choice. Every engine is unique and how it wears in can vary, I personally would just keep in mind that regular maintenance and checks are crucial for the longevity and performance of your motorcycle engine.
But anyway, thank you for sharing your experience with you motorcycle here.
Thank you
Craig
@@TheRepairSpecialist I really appreciate you taking the time to respond. I think based on your opinion I’ll chalk it up to extended break in and stick with the spec for now. The issue it was having was that after an hour or so the engine would start to hesitate, sputtering as though it was running out of fuel although it wasn’t. After checking other things I checked the valves. I don’t guess they were more than .005 tight, but it seems that it caused the issue when it got up to full temp. I wouldn’t have thought the tolerances could be so slight. Thanks again.
Can you do a video on valve overlap? Because i think you may have a realization on what each valve is actually doing in realation to piston position. Great video though nonetheless.
Great cut away engine! Instead of going for top dead center, I rotate the engine until one valve is completely open (on the top of the cam lobe.) This tells me the other valve is completely closed. I adjust the closed valve, rotate until that one is completely open and adjust the other valve - which is now completely closed. This also takes the compression release mechanism out of the equation because it will not be in place with one valve completely open. I wonder if my practice is sound (it seems to be and seems to work?) So many folks do the TDC on compression thing that I wonder. Thoughts?
First of all, thank you for your kind feedback. I really appreciate it. As for the way you adjust your clearances, I also adjust the clearance this way myself. I too have never had an issue with. I find it just as accurate as the method I showed in the video. I think it’s just a case of preference really, and it seems that the more experienced mechanics among do it the way you mentioned. I think it’s also a generation thing to a degree. When I was taught how to set clearance back in the late 80’s, it seemed to be the old fashioned way of doing it. I have some old Honda engine service manuals and in them is the method you explained. I think it’s just become a little more popular in recent years to adjust them as I showed in the vid. But in my opinion your method is great 👍
This is great. My mechanic told me that he did not want to further adjust valves in my 98 Accord to silence the rocker arm clatter - he was afraid of going “too far”. Is that legitimate or is he perhaps lying and never even removed valve cover?