Tappet clearance question

[Alk-3]

Hey everyone. I have a quick question. I have a noisy tappet that I've been chasing in and off for a few months now. It's a brand new turner head, and the truck runs really nice. Always starts on the first try, has good power, doesn't backfire, and in general is just a great running engine. I've adjusted the tappets as per the green bible, but number four is still noisy. When I was last adjusting it, I noticed if I keep turning the engine over (with the hand crank) I could get a much larger feeler gauge under it when it was not set for number 5 fully open. So my question is this.. Should the Tappet be adjusted for .011" while fully closed, or should it be adjusted so that .011 is its widest possible clearance at any stage of the valve train.
I hope that makes sense.
Also, I should mention, if I stick a .003 or so feeler under it while the engine is running, it's quiets down completely.
I don't mind living with the noise of it, but at the same time, I don't want to burn a valve, and don't want to have it adjusted too wide for no gain..
Hope all this makes sense.

[SafeAirOne]

Hmm.

Speaking from 2.5D experience only, I believe that the valve being adjusted shlould be fully closed when the reference valve is fully open. It sounds like your adjusting valve is still in motion when the reference valve is fully open for whatever reason.

[Alk-3]

I'm out here working on it now, and it seems maybe I was perceiving something that doesn't exist. It now seems the number four valve is fully open while valve number five is fully closed. The last time I was fussing with it, I was kind of rushing it, so I may have misjudged it a bit. I have now adjusted it to about .009 and it is quiet. I'm wondering if maybe the rocker itself has worn slightly so that it gives a bit of a false reading. I have had some time to work on it now, and just through some trial and error it seems that .009 is the sweet spot. I have an extra push rod, and so I reached it, and no difference, so I put the old one back, which appears in great shape.
I have now adjusted it back to .011 and will just live with the tapping. I'd rather be safe than burn a valve. As long as I understand the situation, I'm okay with it. Just not knowing why bothers me :rolleyes:
one of the tests I did was ace a .003 feeler gauge in it, while it was running and stood back and listened. It was dead quiet, but as soon as the feeler gauge fell out by itself I could hear the difference immediately.



Hmm.

Speaking from 2.5D experience only, I believe that the valve being adjusted shlould be fully closed when the reference valve is fully open. It sounds like your adjusting valve is still in motion when the reference valve is fully open for whatever reason.

[rwollschlager]

I have now adjusted it back to .011 and will just live with the tapping

Shouldn't it be 0.010?

[Alk-3]

Shouldn't it be 0.010?

Maybe. I'm not sure. I thought it was .011, but I've been wrong many times before.

[yorker]

http://www.roversnorth.com/store/images/Product/large/RNB566.JPG

http://www.lrfaq.org/Series/FAQ.S.tuning_2.25l.html

[TeriAnn]

Sounds like you just replaced the head.

When I have a head off there are a few things I like to do:


Roll each push rod on a flat surface to look for any sign of bending.
Closely examine the cup of each push rod for a hairline crack. I once had a pushrod with a hairline crack. it adjusted well statically but the cup opened up under pressure and sounded like a rod top end problem under load. Since then I've checked.
Check the surface of each rocker arm where it rides against the valve end. If there is any indentation I send the whole shaft off to have all the rocker arms resurfaced.
I also try to wiggle each rocker arm. If there is any noticable wiggle then the bushings are shot and you can never properly adjust the valves.
And I slide each arm sideways along the arm to see if there is any wear on the shaft itself.


Any automotive machine shop can easily recondition a rocker arm assembly with resurfaced rocker arms, new rocker shaft and new rocker bushings reamed to the correct tolerance. A worn rocker shaft assembly keeps you from getting a proper valve adjustment and can affect oil flow to the tops of the valves.

I look at checking over the rocker arm assembly as being part of a valve job or head gasket replacement. What better time to check the assembly over?

[lincoln lass]

Common sense as usual, from Teriann :thumb-up:

[Alk-3]

Yes I have replaced the head just a few weeks ago.. I was chasing this loud Tappet when I discovered the old head had a crack in it..
I did roll each pushrods on a glass surface, and all of them were straight.
I dont think there is a hairline crack because I replaced the noisy pushrods with a brand new one, and no change. I then swapped the old one back in.
I suspect that this might be caused by two things. A bit of slop in the rocker arm bushings, coupled with slightly worn rocker arm surfaces where they meet the valve, and finally, the fact that I've been leaving them a bit wide. I've actually been adjusting them so I can just fit a .012" feeler in there, but it's a bit tight, so I think I just am going to buy the whole rocker arm assembly from turner, and readjust everything to the proper .010" if that doesn't help, then I'm living with it as is.

[cedryck]

nice report terry,,,,

[westcoastkevin]

Yes I have replaced the head just a few weeks ago.. I was chasing this loud Tappet when I discovered the old head had a crack in it..
I did roll each pushrods on a glass surface, and all of them were straight.
I dont think there is a hairline crack because I replaced the noisy pushrods with a brand new one, and no change. I then swapped the old one back in.
I suspect that this might be caused by two things. A bit of slop in the rocker arm bushings, coupled with slightly worn rocker arm surfaces where they meet the valve, and finally, the fact that I've been leaving them a bit wide. I've actually been adjusting them so I can just fit a .012" feeler in there, but it's a bit tight, so I think I just am going to buy the whole rocker arm assembly from turner, and readjust everything to the proper .010" if that doesn't help, then I'm living with it as is.

It seems a little excessive to buy a whole rocker assy. If the noise goes away at 0.009"/0010" when hot. set it like that and forget about it for six months and check it again.

[Alk-3]

It seems a little excessive to buy a whole rocker assy. If the noise goes away at 0.009"/0010" when hot. set it like that and forget about it for six months and check it again.

Yes, I will check the settings once again, and tighten them up a bit before I buy a new rocker assembly, but at this point I'm not expecting any real miracles. I don't mind spending a bit of money for the ease of the job rather than having the old one reconditioned. I have to have the truck on the road, as it's my only mode of transport, so sending the rocker assembly off for reconditioning is not worth the $150 for a new one..

[Alk-3]

Oops. Double post.

[Billy5]

Good morning, not to add confusion to the mix but..lol. The advice I have been given for adjusting the valves is to adjust them so .09 slips through easily, .10 slips through firmly and .11 will not go through at all. Also, I have read that the screws holding the info plate on the valve cover can sometimes make the noise too. I have a tick as well, but my thinking is .10 hot or cold, seems like they wanted some play in there.

[Alk-3]

Okay, I've adjusted everything about four hundred times now, with no luck. I got a whole new rocker shaft and rocker arms from turner, and assembled it carefully, and reinstalled everything.. Still the same tapping.. Uhhg.
So here is what I'm now thinking: the tapping is intermittent, and comes on every couple of seconds, and lasts a couple of seconds. I'm starting to wonder if my number four valve has a slightly out of round cam follower. I've played with things while the engine is running, and slipping feeler gauges under the rocker arm quiets things down completely, but it seems if I try to do this durring the noisy few seconds, it's a bit looser than when it sounds normal. I've replaced the whole head, so new vales, guides etc.. I've now also replaced the whole rocker arm assembly, and I have swapped in a new pushrod, all with no effect on the tapping noise.
For arguments sake, couldn't I just adjust it down to a few thousandths or untill it stops making the noise and leave it at that? Is the specified clearance just an arbitrary number that will allow the valve to fully seat, so really any amount of clearance is sufficient, or does the clearance effectively determin the duration the valve is seated? I'm trying to learn just how this stuff actually is designed to work, and why, in order to determine the safe limitations in actual practice.
On the other hand, does it hurt to have to rocker set for slightly too much clearance.. Say, .013" or .014"?

[TeriAnn]

The little adjustment spec plate on the valve cover is held on by 2 screws. At least one of the screws is directly over a rocker arm and with a slightly thin valve cover gasket, rocker arms have been known to contact the end of the screw.

Try removing the screws and seeing if the tapping goes away. If that's the case the cure is to put the screws back on then grind off a little from the bottom end of the screws.