L71 solid lifter adjusting nuts loosening by themselves
Thread Starter
Melting Slicks
Joined: Dec 2014
Posts: 2,787
Likes: 2,328
From: Central UT
L71 solid lifter adjusting nuts loosening by themselves
'68 L71. Lifters hadn't been adjusted since I bought the car 3.5 years ago, and probably long before that. I adjusted them and noticed 2-3 of the adjusting nuts were (IMO) way too easy to turn, while the rest were just fine. Got everything adjusted, sounded great, made a few good pulls through the gears, and heard a noisy lifter or two.
I adjusted them again Saturday and found one quite a bit out of adjustment (#6 intake). I made the right adjustment, but figured it would just change again until I did something to fix the nut - but went for a short ride anyway. Sure enough - the nut backed off some again.
Can I use poly locks and clear the stock valve covers? Is that the right solution? Is there a different/better solution?
As always, thanks for you help! Paul
I adjusted them again Saturday and found one quite a bit out of adjustment (#6 intake). I made the right adjustment, but figured it would just change again until I did something to fix the nut - but went for a short ride anyway. Sure enough - the nut backed off some again.
Can I use poly locks and clear the stock valve covers? Is that the right solution? Is there a different/better solution?
As always, thanks for you help! Paul
Drifting
Joined: Oct 2006
Posts: 1,875
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From: Persona Non Grata
2022 C3 of the Year Finalist - Unmodified
Perhaps they just need to be replaced. The nuts on mine were all replaced a few years ago and, thus far, hold fine. I can't answer your question re polylocks
Race Director
Joined: Jul 2015
Posts: 13,082
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From: SW Florida.
you usually have to cut the oil drip tangs off inside the valve cover and use double valve cover gaskets to get them to clear. orig jam nuts work fine until 54 years later and too many times being turned.
you really wanna play it safe, replace the rocker studs too...
you really wanna play it safe, replace the rocker studs too...
Last edited by derekderek; Sep 12, 2022 at 06:06 PM.
Racer
Joined: Feb 2002
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I have polylocks under the stock covers and there's no stacking gaskets or doing any bending to the oil drippers. As I recall, I had to grind the tops of the polylocks to get the clearance. Anyway, that's what was done and in the 20 + years since the rebuild, there has been no problems. One other thing about polylocks, it's best to grind the top to the rocker studs flat to ensure good surface for the hex set screw to "bite" into the top of the rocker stud.
Now. as for the stock lock nuts, I sometimes will deform them by whacking them with a hammer or they can be deformed by putting them in vice. It's sort of a trial and error type of thing as you don't want to deform them too much otherwise, the rocker stud threads may get damaged.
Now. as for the stock lock nuts, I sometimes will deform them by whacking them with a hammer or they can be deformed by putting them in vice. It's sort of a trial and error type of thing as you don't want to deform them too much otherwise, the rocker stud threads may get damaged.
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Safety Car
Joined: May 2001
Posts: 4,759
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From: Fairfax Virginia
I personally would want to verify that the nuts are "actually loosening" as opposed to any other possibilities. I would start by checking the cam's lobe by measuring the lift at the valve to be sure it is not something more serious happening inside your engine. It would be a fairly easy thing to check unless you decide to check all 8 cylinders.
If your cam's Lobes were getting wiped it might explain why the #6 intake is looser than the rest. I personally like to eliminate the possibilities before assuming the problem is solved. Even a collapsing lifter could be the cause but you should check to be sure and it might save you some hassles down the road.
Any bigger problems are best caught "early" especially on a Big Block with the higher cost of parts. With today's oil you need to double check because wear can be happening inside the engine that is presenting itself as something fairly simple.
Best Regards,
Chris
If your cam's Lobes were getting wiped it might explain why the #6 intake is looser than the rest. I personally like to eliminate the possibilities before assuming the problem is solved. Even a collapsing lifter could be the cause but you should check to be sure and it might save you some hassles down the road.
Any bigger problems are best caught "early" especially on a Big Block with the higher cost of parts. With today's oil you need to double check because wear can be happening inside the engine that is presenting itself as something fairly simple.
Best Regards,
Chris
Thread Starter
Melting Slicks
Joined: Dec 2014
Posts: 2,787
Likes: 2,328
From: Central UT
Made me laugh with that one! I've been on the forum long enough to - at least most of the time - understand who the smart and experienced ones are. And you are among them IMO. Thanks, Paul
Thread Starter
Melting Slicks
Joined: Dec 2014
Posts: 2,787
Likes: 2,328
From: Central UT
I personally would want to verify that the nuts are "actually loosening" as opposed to any other possibilities. I would start by checking the cam's lobe by measuring the lift at the valve to be sure it is not something more serious happening inside your engine. It would be a fairly easy thing to check unless you decide to check all 8 cylinders.
If your cam's Lobes were getting wiped it might explain why the #6 intake is looser than the rest. I personally like to eliminate the possibilities before assuming the problem is solved. Even a collapsing lifter could be the cause but you should check to be sure and it might save you some hassles down the road.
Any bigger problems are best caught "early" especially on a Big Block with the higher cost of parts. With today's oil you need to double check because wear can be happening inside the engine that is presenting itself as something fairly simple.
Best Regards,
Chris
If your cam's Lobes were getting wiped it might explain why the #6 intake is looser than the rest. I personally like to eliminate the possibilities before assuming the problem is solved. Even a collapsing lifter could be the cause but you should check to be sure and it might save you some hassles down the road.
Any bigger problems are best caught "early" especially on a Big Block with the higher cost of parts. With today's oil you need to double check because wear can be happening inside the engine that is presenting itself as something fairly simple.
Best Regards,
Chris
When I adjusted them a few weeks ago I made note of three that were loose (compared to the others) after I adjusted them. #6 intake was the 'loosest'. I don't think they had been touched in over 20 years and when I adjusted them 13 stayed nice and 'tight', and 3 were 'loose' on the stud, compared to the others, after I turned them.
After 3-4 good pulls through all the gears I had a bit of noise and sure enough, #6 intake was the culprit. So I adjusted it back and all was quiet again (or, the right sound for solids). I went for a drive, and just as I figured, after a mile or so I got the same 'too loose' tappet sound. #6 was loose again. I could move the nut with my fingers. There may be some other stuff going on, but it sure pulled like a freight train after I got the tri power working. But, we'll see! Thanks again, Paul
PS: if the lifters on this engine collapse, I have some real problems.
Is my vette stock?? HAHA
Joined: Oct 2015
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I used some polylocks under stock covers with no Issue.You may have to look for some short ones... If you go the polylock route grab one of these vavle lash tools as well. You are going to want something to make the adjustments easy and to lock them easy without having them change your lash. I like to get them very close and then turn the nut and the locking bolt at the same time. IT takes some practice but you can get pretty good at it after 16 times doing it...
https://www.summitracing.com/search?...olylock%20tool
these are for non roller rocker arms and 3/8 24 studs
https://www.summitracing.com/search/...ocker+arm+nuts
https://www.summitracing.com/search?...olylock%20tool
these are for non roller rocker arms and 3/8 24 studs
https://www.summitracing.com/search/...ocker+arm+nuts
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,094
Likes: 4,449
From: Marlton NJ
Crower makes some short polyloks that clear stock valve covers.
Yes the "pinched thread" on the original nuts wears out after a while and becomes loos e and too easy to rotate. There is a torque-to-turn spec they should meet. But why bother?
Polyloks will never back off, if tightened right, and if one gets loose, then you know you need to check for something wearing.
Yes the "pinched thread" on the original nuts wears out after a while and becomes loos e and too easy to rotate. There is a torque-to-turn spec they should meet. But why bother?
Polyloks will never back off, if tightened right, and if one gets loose, then you know you need to check for something wearing.
Thread Starter
Melting Slicks
Joined: Dec 2014
Posts: 2,787
Likes: 2,328
From: Central UT
I used some polylocks under stock covers with no Issue.You may have to look for some short ones... If you go the polylock route grab one of these vavle lash tools as well. You are going to want something to make the adjustments easy and to lock them easy without having them change your lash. I like to get them very close and then turn the nut and the locking bolt at the same time. IT takes some practice but you can get pretty good at it after 16 times doing it...
https://www.summitracing.com/search?...olylock%20tool
these are for non roller rocker arms and 3/8 24 studs
https://www.summitracing.com/search/...ocker+arm+nuts
https://www.summitracing.com/search?...olylock%20tool
these are for non roller rocker arms and 3/8 24 studs
https://www.summitracing.com/search/...ocker+arm+nuts
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,216
Likes: 9,354
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Im sure he checked the sizes before ordering, the links were general pieces not just one. IF he had ordered the wrong size due to my suggestion then its on me for not posting the correct size. If thats the case we can work it out
Old Pro Solo Guy
Joined: Dec 2017
Posts: 8,094
Likes: 4,449
From: Marlton NJ
Here's a link to the short Crower polyloks for BBC:
https://www.summitracing.com/search/...rder=Ascending
Here's a comment from reknowned racer David Pozzi: "Don't use Polly locks with stock rocker studs. Stock studs are not machined flat on top, the nut can tilt to one side when tightened & the uneven stress split the nut along the thread. It happened repeatedly on a friends race car, small block with BB 7/16" GM studs. Some brands of rockers use a thinner wall nut than others. I know an engine builder who spot faces the GM studs on a valve grinder machine, but ARP stuff isn't that expensive and it's ready to go."
My engine builder even went so far as touching the face of my ARP studs, just to make absolutely sure they are flat. But he is just that meticulous. He built many thousands of 9000 rpm drag engines, that don't break. Sometimes he just shortens the polyloks, 3/8" or so. But he always clays the polylok to valve cover clearance. If not, you can get some pretty funny noises LOL!
My rule is: Any non factory part requires double checking everything.
https://www.summitracing.com/search/...rder=Ascending
Here's a comment from reknowned racer David Pozzi: "Don't use Polly locks with stock rocker studs. Stock studs are not machined flat on top, the nut can tilt to one side when tightened & the uneven stress split the nut along the thread. It happened repeatedly on a friends race car, small block with BB 7/16" GM studs. Some brands of rockers use a thinner wall nut than others. I know an engine builder who spot faces the GM studs on a valve grinder machine, but ARP stuff isn't that expensive and it's ready to go."
My engine builder even went so far as touching the face of my ARP studs, just to make absolutely sure they are flat. But he is just that meticulous. He built many thousands of 9000 rpm drag engines, that don't break. Sometimes he just shortens the polyloks, 3/8" or so. But he always clays the polylok to valve cover clearance. If not, you can get some pretty funny noises LOL!
My rule is: Any non factory part requires double checking everything.
Thread Starter
Melting Slicks
Joined: Dec 2014
Posts: 2,787
Likes: 2,328
From: Central UT
Hi, I wanted to provide an update on the solution I implemented.
I got the short polyloks. While I was at it, I found some Melling rocker nuts that looked like they were high quality. I decided to install the Melling nuts on the two rockers that had loose nuts, and they were nice and tight. I took the car out and ran it through the gears a few times and it appears to have solved the problem. I rechecked the lifter adjustments when I got back, and they were spot on. I'm going to keep the poly's and install them (and new studs) if I have any further issues but, for now, it's good to go. Just in time for the first snow.
Oh well, I have several winter projects to keep me going.
Again, thanks to each of you who provided help and guidance! Paul
I got the short polyloks. While I was at it, I found some Melling rocker nuts that looked like they were high quality. I decided to install the Melling nuts on the two rockers that had loose nuts, and they were nice and tight. I took the car out and ran it through the gears a few times and it appears to have solved the problem. I rechecked the lifter adjustments when I got back, and they were spot on. I'm going to keep the poly's and install them (and new studs) if I have any further issues but, for now, it's good to go. Just in time for the first snow.
Oh well, I have several winter projects to keep me going. Again, thanks to each of you who provided help and guidance! Paul