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1941 valve adjustment


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I know this topic has been discussed a lot and I'm sorry to bring it up again but I could not find any reference to anyone who has adjusted their valves the way the manual suggests - hot and on a running engine. Has anybody tried this? Didn't you need 3 hands, one to loosen/tighten the locking nut, another to adjust the lash (screw) and a third to stick the feeler gauge in?  How did you do this with the rocker moving up and down?? I'd really like to do this properly and talk to somebody who's done it as I'm leery of doing it with the engine not running because then you have to bump the starter and hope the valve is in the right position, and the engine/valves will cool off as you go. I was hoping there would be a Youtube vid but no luck.  The procedure for my Packard was adjusting them cold, and turning the engine over by a socket on the harmonic balancer but no room on a Buick.....

Thanks,

Peter

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I did them hot and running on my Limited. Drive it for a while to get everything nice and warm, then dial the idle down as far as it will go and still stay running (like 300 RPM, it'll be rough, it'll be stinky, but it will still run). Remove the valve cover (you have a new gasket, right?). I tried using the one-handed tool, but it doesn't work as well as a simple box wrench and a screwdriver on a running engine. I found that I could adjust the valve with the screwdriver while I checked clearances with a feeler gauge (slight drag as you move it through), then I noted where the screwdriver slot was pointing and tried to lock it down at that point. Then I double-checked clearance once it was tight to be sure that nothing moved around--if it did, I tried again. On several I simply adjusted by ear until they were quiet, then checked clearance, and as long as it was .014 to .017, I left it alone.

 

That said, if your valves are quiet, LEAVE THEM ALONE! Don't go looking for problems where none exist. While adjusting valves was probably part of routine maintenance back then, it's probably a once-in-a-lifetime chore today. My valves were silent yet I figured that I should probably check them since I never had and didn't trust the previous owner's skills. Sadly, after I screwed around with them, the valves got VERY noisy and I had to try three or four times before I was satisfied. Now that I have them dialed in pretty well, they're OK but still a bit noisier than they were. As with many of the projects I undertake on my car, the valve adjustment was one that I regret doing.

 

If you don't need to do it, if they aren't noisy (a little ticking is OK), then I would say good enough and don't mess with it. They're solid lifters, so there's always going to be a little noise. A little ticking is OK.

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Well dang, I followed your thread back then Matt but wrongfully thought you did it with the engine off.  Sorry about that. 
 

My valves are not overly noisy but I want to make sure none are too tight, which I think a few may be. I did a quick engine- running lash check with the engine cold and found the .015” feeler gauge was a tight fit on at least 2 valves.  If they are at .015” cold, they will be a lot tighter hot which is, err, uncool, as in, bad. Maybe I’ll just mess with the few I’m concerned with. 
Thanks Matt

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With the engine hot, running at idle and the cover off; take the proper feeler gage and slide it between the rocker and valve.  If it goes in easy and the tick goes away,that valve could use some adjustment.  If it doesn't go in try a thinner feeler until it goes in.  If it is way off from the correct feeler, that valve needs to be adjusted.  

 

Bob Engle 

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2 hours ago, Matt Harwood said:

That said, if your valves are quiet, LEAVE THEM ALONE!

 

That's definitely the advice that I got (and followed) when I had Don Micheletti first look at my Super.  The valves were so quiet that he first thought someone had installed hydraulic lifters.  When we determined that was not the case, Don said, "Whatever you do, don't touch them!"  I haven't, and they continue to be super quiet.

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Whoa...great vid but not exactly confidence building. The guy with the screw driver and wrench was having a tough time...and, of course, there were 2 people when I’m hoping to do this without help. 
thanks for posting, most informative. 

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One person can do it with the right tool. Here is one example: https://www.ebay.com/itm/Snap-on-Tools-V-21A-Valve-Clearance-Adjusting-Tool-Vintage-Old-Antique-1944/373074670383?epid=1823968628&hash=item56dcfbb32f:g:bmMAAOSw3-te18y0

 

I personally have a different brand but the snap on one will work well. If you want to do it with a screw driver and wrench, it is a lot more work. The trick to make that easier (but not as easy as the correct tool) is to put a short piece of rubber hose over the end of the screwdriver so the rubber hose helps hold the screwdriver tip on the tappet adjustment screw. 

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Thanks. I learned of that tool here and there are usually several for sale on eBay. Matt didn’t have much luck with it so I backed off. In any event, I think things will go smoother if I can recruit a helper. An extra set of hands can’t hurt. Thanks again for the suggestions,

peter

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Yea man I wish I could but I’m worried as a couple of my valves are .015” COLD. I ran a .015” feeler gauge through all of them cold, right after start up to help identify any tight valves. Most of them measured more than .015” but 2 were a little snug. May just adjust those. As you know, tight valves are a bad thing. 

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1 hour ago, valk said:

Yea man I wish I could but I’m worried as a couple of my valves are .015” COLD. I ran a .015” feeler gauge through all of them cold, right after start up to help identify any tight valves. Most of them measured more than .015” but 2 were a little snug. May just adjust those. As you know, tight valves are a bad thing. 

 

 IF YOU MUST,  get it hot and then check all of the clearances. Yes, too tight can be bad, but not fatal as long as there is some clearance.

 

  Ben

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2 hours ago, valk said:

Yea man I wish I could but I’m worried as a couple of my valves are .015” COLD. I ran a .015” feeler gauge through all of them cold, right after start up to help identify any tight valves. Most of them measured more than .015” but 2 were a little snug. May just adjust those. As you know, tight valves are a bad thing. 

 

Yes, but are they noisy?  That's the question you should be asking yourself.

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After sleeping on this, I’m going to warm it up thoroughly and measure all the valves by the “go, no- go” method. Measuring the valves while the engine is running is easy and accurate so I’ll get good baseline measurements. I’m hoping only a few will need attention so I’ll take it from there, and adjust the outlier valves with the engine off. And then check everything again with the engine running. 
 

I always thought that only loose valves made noise and tight valves do not so relying on noise to identify tight valves won’t work. I feel pretty confident now but then again, it’s early....

thank you all for your help and sorry about beating this topic to death. 
peter

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The go/no-go method isn't really all that it's cracked up to be. The .015 feeler may just fit, but the .016 feeler may also squeeze in there. I found it very difficult to get it to that exact edge where one would go in but the other wouldn't. As I said, some I just tuned by ear until they were quiet and then measured and as long as they were more or less close to spec, I left them alone. Even if one or two are tight, my gut says to leave them alone. I [wrongly] assumed mine were haphazardly and incorrectly done simply because of all the other messed-up stuff I'm finding as I go through my car, but I ultimately learned that someone set up those valves to make them as quiet as possible and did a very good job. So what if a few were over or under spec? There's wear to consider, particularly on the rocker arm tip which can not only wear but also changes shape, so it's not a definitive yes/no situation with 80-year-old parts with untold miles of usage. Like I said, I should have just left it alone. Now it's in my head and every time I start it and hear a little ticking, I think, "I can do better."

 

Quiet is still probably your best barometer if everything is pretty close to spec. Much too tight (I'd say less than .012) is bad, but just a little tight won't hurt anything. Too loose won't hurt anything, either, but it's noisy.

Edited by Matt Harwood (see edit history)
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Couple of final thoughts, 1) my valve train is close to new so wear would be minimal; and 2) the document below is taken from the official Buick "1941 Buick Parts and Service Bulletins" which warns of overly tight valves. 

buickvalveadjustment.jpg

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i don't get it. I understand that the hot block and head raises the rocker shaft and opens the lash. But the pushrods also expand, but to a lesser degree because the oil is not as hot as the water. OK. So the hot water accounts for a lot of increase in lash, but a small amount of expansion in the pushrods should make up for some of that. (any increase in pushrod length would decrease lash). Right? Seems to me that we ought to know how to adjust valves at room temperature (no warm-ups, just room temp) that becomes the proper gap at normal operating temperature. 

I was not able to manage adjustment while running. I ended up adjusting for .017 cold, and then after a run (probably not highway hot) they were .014 to.016) They are a little noisy so I may revisit.

Thoughts anybody? 

 

 

 

 

 

 

 

 

 

i

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It varies by engine. some types loosen with heat, some tighten. Cast iron may expand at a different rate than steel? Rocker arm ratio would also have some effect. Hot valves are probably responsible for the tightening.

 

I would rather hear them a little too much than NOT hear them. Too tight will get you burned valves. When there is doubt, I recheck with a dial indicator at the valve. It compensates for wear on the surface the feeler gauge touches (the rocker arm and valve tip on a Buick).

 

Edited by Bloo (see edit history)
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I've learned over the years that the car will usually tell you what it needs. When something isn't quite right, I try to trust my gut instincts. If the valves are quiet and everything else is otherwise healthy, you'll know it. If they're tight enough to burn a valve, you'll know it. If they're too loose, you'll know it. Again, mine were virtually silent and I stupidly thought I should just go in and mess with it anyway. Now I know better. These cars aren't driven hard or fast enough to make a slightly-too-tight valve an issue. Much too tight is bad, but one or two thousandths on either side won't affect anything. I probably drive mine harder than anyone else and I'm not worried at all about it. One, maybe two, are still ticking at idle but it's otherwise quiet. Maybe I'll go after them, maybe not, it runs like a million bucks now. As Bloo points out, the tips of the rocker arms are going to have some wear and there's no such thing "brand new" rocker arms so it's not quite going to be like it was when it was new. The shape may have changed subtly. If absolute perfection is desired, the dial indicator method is by far the best way but on these cars that kind of precision isn't really necessary and again, the car will tell you if you get it wrong.

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Gentlemen...........fix it tilt's broke! 😎

 

I get both sides of the argument........I would check the valves while it's hot and running........just my 2 cents.

Edited by edinmass (see edit history)
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3 minutes ago, edinmass said:

Gentlemen...........fix it tilt's broke! 😎

 

 

That's my technique and nobody does it better.

 

Nobody.

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I used to keep 4 Buick straight 8's running and I learned the best way to get the most power out of the engine was to adjust the valves.  I would do a hot adjust on a running engine, then recheck the clearance again to make sure I got it right.    As I was told by a second generation straight eight engine rebuilder (Jim Swanson) adjusting the valves hot with the engine running allows one to adjust excess clearance due to wear out of the valve train.

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Dave B came by in his beautiful ‘41 today and we measured and adjusted my valves hot. Since they were quiet to begin with, and there is strong support for leaving well enough alone, we only adjusted 2 (with the engine off) that were clearly not as tight as the others and buttoned her up. And now I have peace of mind none are too tight. Thank you Dave! 

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