Valve Adjustment Gain Anything?

calimobber

calimobber

Member
So long story short 12 years ago my tensioner bolt stripped when doing the timing belt so I red locked tightened it and it held 13 years but finally got loose and messed up my belt.

So im tearing into the timing belt/ water pump...and figured this is a good time to do the valve cover too. I might as well check the valves while the cover off.

So the big question is has anyone who took the time to swap shims and get it back into spec did you feel any difference? any more power or mpg?

If you dont really gain anything other than maybe preventing possible burnt valves im leaning on prob skipping adjustment unless waaay off. at 275k miles ill prob just keep her going and replace the whole engine with a JDM if it gets that bad.
 
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I would agree, unless the valves are really tight, I wouldn't mess with them and it's doubtful you would notice any change in performance by bring valve clearance into spec that are not exceptionally tight.
 
I did mine at ~325k miles recently (for the first time). About 1/4 of the valves were out of spec slightly, none were excessively tight. Depending on use patterns and oil change history, your results will vary. If you have the valve covers off, definitely check them, at least. I did mine in preparation for a supercharger install...

Report actual clearances and get feedback at that point. Unless you really need to get back on the road ASAP, there's a chance it will be worth doing the valves even though it is a pain.

-Charlie
 
I checked my 2000 4runner with around 250k miles and the valves weren't technically out of spec but they close to being out so I adjusted them back to the middle or upper part of the spec. However, in the video below, my buddy Wei's valves were way out of adjustment. How he didn't burn up a valve, I don't know. If I were you, I'd check your valve lash. Ignorance isn't always bliss. Replacing heads is a ton of work.

<iframe width="560" height="315" src="https://www.youtube.com/embed/MOlmjtlO7TI?si=ot4G5k9OIU0F5sSt" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
 
mtbtim said:
I checked my 2000 4runner with around 250k miles and the valves weren't technically out of spec but they close to being out so I adjusted them back to the middle or upper part of the spec. However, in the video below, my buddy Wei's valves were way out of adjustment. How he didn't burn up a valve, I don't know. If I were you, I'd check your valve lash. Ignorance isn't always bliss. Replacing heads is a ton of work.

<iframe width="560" height="315" src="https://www.youtube.com/embed/MOlmjtlO7TI?si=ot4G5k9OIU0F5sSt" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
Click to expand...


Yeah Ive watched your videos timmy for everything, love it. But I havent heard a single person with burnt valves...i know i know it prob does happen but out of everyone im shocked how little we hear, it seems like even when they finally get out its still not enough to hurt anything. I guess ill see when I dive in. i have a few cars so it can sit but I like to get back at it soon. thanks.

mostly was curious if it gained any power back but guess not
 
That would really depend how far the valves are out of spec. I know if they get too tight, there is a possibility of cracking the head. As that's a secondary cause of cracking heads between the middle cylinders. The first cause is extreme overheating warping the head. Plus if they are staying open, your definitively loosing power. Every 250 to 300K seems to be the range for good valve adjustment check. If the cover is off. Like the others stated, wouldn't hurt to at least check the valve clearance.
 
I watched Tim's video completely and his advice at the end is spot on. I had a Honda motorcycle, CB900F, DOHC, and it had the same valve adjust procedure as it was shim on bucket. Make your valve lash readings, remove each shim and mic them, reinstall them and then go order/find the shims you need to complete the job and then complete the job. Having the right tools is also a bonus, Honda had an excellent tool for the job and it was not a bad job at all. This, however, is more involved.
 
I'd for sure check them while you've got access. And leave it along unless you find tight or really loose valves. Loose valve just make noise, they have to be ridiculously loose before it starts causing performance issues (delays valve opening and shorter duration), tight valves can cause a burnt valve if they get much tighter and start hanging open slightly.
 
Well valve gaskets replaced and valves checked.

everything was in spec except 2 exhaust were slightly over. I think the high limit is .014 on exhaust and one or two was .016 so I think all is well. Most intakes were still rock solid at .006 or whatever which is wild for 278k miles.

Plans to have all the timing belt put back together and have her running tomorrow. I swear the most annoying thing ever is to get the timing belt on and do a manual rotation to find the crank is one tooth off, then have to re do it all and have the same thing happen. Def need to have the crank a little to the left of the mark to get everything to align right.

Cheers
 
The big problem I found when adjusting them was the wait time to get new shims delivered. It took almost a week to measure, calculate, order, receive and install the shims. They were about $12 each, so pre-ordering assorted sizes was too expensive for me. I used ToyotaPartsDeal.com who shipped from OR, which is next door to me, so shipping may take longer for others. I found a couple out of tolerance and am happy I did it.
 
bwallick said:
The big problem I found when adjusting them was the wait time to get new shims delivered. It took almost a week to measure, calculate, order, receive and install the shims. They were about $12 each, so pre-ordering assorted sizes was too expensive for me. I used ToyotaPartsDeal.com who shipped from OR, which is next door to me, so shipping may take longer for others. I found a couple out of tolerance and am happy I did it.
Click to expand...
I had some nervous time after installing the shims I had calculated... luckily, it all worked out decently.

-Charlie
 
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