Mechanical lifter problem/question
Thread Starter
Instructor
Joined: Feb 2002
Posts: 182
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From: Philo CA
Mechanical lifter problem/question
I was getting some serious lifter noise from the driver's side last weekend so I pulled the valve cover this morning. All of the rockers spec'd out perfect (.022) except for one. It was EXTREMELY loose (2nd rocker, 1st cylinder) so I tightened it down, put the cover back on, started it up, and the problem was solved. Can anyone explain why this would happen? I had the heads rebuilt about 1,000 miles ago so I thought they would be trouble free for a long time.
Under normal driving conditions how often should the valve lash need adjusting?
Under normal driving conditions how often should the valve lash need adjusting?
Le Mans Master
Joined: Dec 2000
Posts: 7,245
Likes: 4
Re: Mechanical lifter problem/question (sixtyseven427)
The nut may have lost its "squeezeability". Someone else will describe it better than I did with that word.
With the stock cam (assuming you have the stock 435 cam) every couple of months was my experience with some daily driving.
With the stock cam (assuming you have the stock 435 cam) every couple of months was my experience with some daily driving.
Le Mans Master
Joined: Apr 2000
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From: New York New York
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Re: Mechanical lifter problem/question (sixtyseven427)
It is not uncommon to have a self locking rocker nut back off. Did you use new lock nuts when you did the heads? They say once you remove the rocker arms you should replace the nuts. On race motors we used to use "poly-locks", which used an allen lock screw to prevent them from backing off.
With solid lifter cams this happens more frequently than with hydraulic lifters. I would guess it has to do with the clearance, maybe the pounding against the valve tip as the rocket hits it?:confused:
Maybe someone will know more.
As far as how often, just do it when you start to hear the difference.
With solid lifter cams this happens more frequently than with hydraulic lifters. I would guess it has to do with the clearance, maybe the pounding against the valve tip as the rocket hits it?:confused:
Maybe someone will know more.
As far as how often, just do it when you start to hear the difference.
Le Mans Master
Joined: Dec 2000
Posts: 7,245
Likes: 4
Re: Mechanical lifter problem/question (plaidside)
Plaidside,
You said it better than I. I should have added the phrase, "Did you use new lock nuts when you did the heads? They say once you remove the rocker arms you should replace the nuts.". :yesnod:
You said it better than I. I should have added the phrase, "Did you use new lock nuts when you did the heads? They say once you remove the rocker arms you should replace the nuts.". :yesnod:
Safety Car
Joined: Mar 2002
Posts: 3,780
Likes: 442
From: Southwest MI
Re: Mechanical lifter problem/question (67HEAVEN)
I started using the aftermarket tall nuts with the allen head set screw locks long (over 25 year)ago, they work good for me. Based on what you described, don't rule out the stud working out a bit (that's why we now use screw in studs).
Race Director
Joined: Apr 1999
Posts: 10,866
Likes: 717
From: Beverly Hills/Pine Ridge Florida
Re: Mechanical lifter problem/question (66427-450)
66427-450 makes a good point. If you still have the original "press in" studs, check to see that one hasn't pulled out. I had the heads rebuilt on my 63 about 5 years ago. The fellow who did them insisted on replacing the studs. He "pulled" the originals, and "pounded in" new press in replacements. To make a long story short, within weeks, I had one pull loose, and the valve started to clatter. Replaced it with a screw in stud. Fast forward another month or so...pulled 3 more. Replaced the remaining 15 studs with screw in's that time and have not touched my valves since. Chuck
Melting Slicks
Joined: Aug 1999
Posts: 2,848
Likes: 3
From: Atlanta, Ga, Fulton
Re: Mechanical lifter problem/question (Chuck Gongloff)
Another story of "things you gotta do" that don't work out. He insisted you do that and you end up holding the bag. Just great! I try real hard not to listen to the "street racer / hot rodder wisdom" ! Had the best luck with plain old stock parts in most cases. I know a machinist who drills holes thru the stud and the stud boss then put pins thru the holes to prevent the studs from pulling out. always seemed to work but the real issue is usually the lock nut. Always hated the poly locks cause you ended up needing some tall aftermarket valve cover that had the name of the manufacturer smeared all over it. Never liked those.
Melting Slicks
Joined: Oct 2001
Posts: 2,064
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From: Halifax, Nova Scotia, Canada
Re: Mechanical lifter problem/question (sixtyseven427)
In the "old days" we always double nutted the rockers. Adjust to desired setting, then spin on a regular nut, and tighten against the original nut.
Not an elegant solution, however it worked very well with our 'limited' budget cars.
Not an elegant solution, however it worked very well with our 'limited' budget cars.
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Melting Slicks
Joined: Oct 2001
Posts: 2,480
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From: Wa.
Re: Mechanical lifter problem/question (TheOman)
Always hated the poly locks cause you ended up needing some tall aftermarket valve cover that had the name of the manufacturer smeared all over it. Never liked those.
Team Owner
Joined: Oct 2000
Posts: 38,897
Likes: 1,925
From: Washington Michigan
Re: Mechanical lifter problem/question (Barry's70LT1)
All BB's have screw-in studs from the factory; did you use new rocker ball nuts when the heads were rebuilt recently? If those torque-prevailing nuts have been off and on more than a couple of times, they lose their prevailing-torque feature and can loosen up. I always use new nuts after a teardown.
[Modified by JohnZ, 12:18 PM 5/25/2002]
[Modified by JohnZ, 12:18 PM 5/25/2002]
Melting Slicks
Joined: Aug 1999
Posts: 2,848
Likes: 3
From: Atlanta, Ga, Fulton
Re: Mechanical lifter problem/question (JWD01)
Really what brand do you have? Not really critical right now since both my small block and big block both have screw in studs but I would like to know what brand clears the covers if you can tell me.
Melting Slicks
Joined: Oct 2001
Posts: 2,480
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From: Wa.
Re: Mechanical lifter problem/question (TheOman)
Really what brand do you have? Not really critical right now since both my small block and big block both have screw in studs but I would like to know what brand clears the covers if you can tell me.
After rereading the original post I realized the topic was about big blocks. I doubt if any brand will fit under the stock covers for them. I went aftermarket on my LS6 Chevelle but I was using roller rockers and had no choice. :cheers:
