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  #1  
Old 08-23-2003, 12:50 AM
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new cam and ball studs

just to add to chuck's post...

now that you have run different rockers on your cam (each lobe and rocker have a unique relationship) that is to say that when you remove a rocker every publication tells you to keep the relation of which rocker went where so that you won't migrate a problem of bad lifter to the cam..

even when you first start any new cam with new lifters once you've established oil pressure you must raise the rpm for proper break in of the cam. now that you have switched rockers to you cam you may have drug in another set of wear patterns which may shorten the service life of your cam.

now with that said i ran my 88 for several months banging away. i figured the cam was already lunched so how much more could i damage it. what really got me motivated to fix the problem is that it was embarassing at drive thrus. when i finally pulled it down i had only 1 rocker that failed. the cam had ground about .060 in off the top of the rocker. well that grinding also took the cam out. now the 1 rocker was bad 7 were still good but i wouldn't dare put an old rocker with wear patterns on a new cam. think about it... you wouldn't put a new bearing on an old race that had been scored right!!

good luck with your project and let us know how things turn out.
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1972 350sl Red/Blk 117k
1988 420sel charcoal/Blk 140k
1987 420sel gold/tan 128k
See My Cars at:http://mysite.verizon.net/res0aytj/index.html

Pound it to fit then Paint it to match!

There is only First Place and Varying degrees of last!

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  #2  
Old 08-24-2003, 03:28 PM
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Clacking from Valve Covers - rocker arms?

I read the articles Chuck recommended on hockey pucks and ball studs.

In my opinion, the clacking is louder with the new used set of rocker arms. Maybe my mechanic did not know that when changing the rockers that the pre-load adjustment has to be done on the HLCs? Maybe the old shims were left in place and just the rock arms were changed?

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  #3  
Old 08-25-2003, 01:58 PM
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good morning

what happened when i replaced my cam was that the current ball stud / height checking tool showed that i did not need to adjust any of them. i did buy the factory tool to check and each one was dead nuts in the middle of the red line. coincidence? don't know the only thing i do know is that i replaced the one bad ball stud, all new rockers and the cam and i made no shim adjustments.

as for your situation that is a big fat maybe. you'd have to look and see (using a height checker) where the red line is in comparison to the ball stud. but believe that there is no mistake where that red line is on the height checker. they know exactly the dimension on the rocker, cam lobe ball stud and valve spring height/shim. that height checker

i made a post last week but it never showed up. in it i had made a comment about putting a new bearing in an old race that had been scored. well that is my take on putting different used rockers on a known good cam. you just shouldn't do it.

the cam rocker relation is unique to each lobe. you would never take out rockers and throw them in a box mixed up then re install on your cam on just any lobe nor would you use old rockers on a "new" cam. note: a new cam requires an initial break in. when you install a new cam you must run up the rpm and let is set for 20 plus minutes so the cam and rockers can break in.

so was your mechanic correct in doing so... don't know i just know that i would never do what he did. now i'm sure he's had a wide spread of customers some say fix it as cheap as you can and some that are the make it perfect customer. he may have miss read what you told him.

i don't recall now. did he replace any ball studs in this process?? if he didn't you may still have the same problem now as you did in the beginning. the tapping noise will come from a ball stud collasping or the rocker/cam is ground down changing the rocker's angle thus releasing the valve spring's force on the rocker and viola a tapping sound.

you may get varing opinions on my take of the rocker and lobe relation and folks who have never bothered with how the rocker and lobe work together. this has just been "IMHO".

good luck
craig
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Thanks Much!
Craig

1972 350sl Red/Blk 117k
1988 420sel charcoal/Blk 140k
1987 420sel gold/tan 128k
See My Cars at:http://mysite.verizon.net/res0aytj/index.html

Pound it to fit then Paint it to match!

There is only First Place and Varying degrees of last!

Old age and deceit will overcome Youth and Enthusiasm every time!

Putting the square peg in the round hole is not hard... IF you do it fast enough!

Old enough to know better but stupid enough to do it anyway!
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  #4  
Old 08-25-2003, 11:01 PM
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No ball studs or HLCs were replaced. I'm thinking I may well have the same problem as originally identified.

I have never heard of soft cams on a 116 engine, have you? I presume it really depends on the frequency of the oil changes, but I'm thinking the cams should be good 400K to 500K miles. I only have about 165K miles on it. I would think the first components to need replacing would be the HLCs.

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