rendyx
New Member
Considering my valve lash adjustment is approaching, I'm curious as to what is the cause for, and how to prevent, shims from ejecting. Thanks!
Preventing ejected shims
- Thread starter rendyx
- Start date
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rangerj
Active Member
RENDYX,
In order for a shim to get ejected it has to have room to get out. If the gap between the shim and the cam lobe is within specification, and everything else is in working order, an ejected shim is highly unlikely.
However, if the gap is out of spec and/or a spring is broken, or lost some of its tension and is not at the proper hight, then the shim could have enough room to escape from its proper place.
If the "bucket" the shim sits in sticks in its bore for a split second, the shim could have room to get out.
If you put together weak springs, worn shims and cam lobes, and high RPMs, all kinds of nasty stuff can happen.
If you are going to push an engine to its limits, you will have to maintain it to minimize breaking things. Even with the best care possible, as the number of miles goes up so does the amount of care and replacement parts.
Think about all this the next time you "drop the hammer" for a "launch". eek!
rangerj
In order for a shim to get ejected it has to have room to get out. If the gap between the shim and the cam lobe is within specification, and everything else is in working order, an ejected shim is highly unlikely.
However, if the gap is out of spec and/or a spring is broken, or lost some of its tension and is not at the proper hight, then the shim could have enough room to escape from its proper place.
If the "bucket" the shim sits in sticks in its bore for a split second, the shim could have room to get out.
If you put together weak springs, worn shims and cam lobes, and high RPMs, all kinds of nasty stuff can happen.
If you are going to push an engine to its limits, you will have to maintain it to minimize breaking things. Even with the best care possible, as the number of miles goes up so does the amount of care and replacement parts.
Think about all this the next time you "drop the hammer" for a "launch". eek!
rangerj
sdpatt
Sr. SHO Engr.
Once again, rangerj hits the nail on the head.
It always makes me feel good to see that valve gapping worksheet put to its intended use. Bravo.
It always makes me feel good to see that valve gapping worksheet put to its intended use. Bravo.
Slick_3.2
New Member
When I adjusted my valves I was worried about the same thing. I ended up just putting a little dab of JB weld under each shim. Make sure you re-check the gap after you do it.
philallemang
New Member
why did you put BJ WELD under them???? you probably not going to be able to get them back out!!!!!! they are not going to come out unless you have really sloppy cams and shimms.
shojuan
New Member
What he said! eek!
RStalveyARFF
too many shos
That was by far the most idiotic thing I have ever read on this forum. I'm sorry if that ****** you off but it's true. Not only did you change the clearance, you also made it so the shim would not have a solid, flat surface to sit on. Next time you pull your motor apart, check each shim's thickness. I bet you anything that there is EXTREME uneven wear.
sdpatt
Sr. SHO Engr.
No! You need to pull each and every one of those shims out and clean the glue off of the shim and tappet. You have disabled several of the key features of the inverted bucket tappet arrangement. The glue, while it sticks, which won't be long, will prevent the constant rotation of the shim under the cam lobe and defeat the oil film suction that helps to hold the shim in place. Also, if you added the glue after you determined the correct shim thickness, you reduced the measured gap by even the thinnest of films under the shim.
Since the shims are locked in place rather than floating on the thin film of oil in the tappet bucket, the wear may be rapid and significant. You may already have paid a high price.
[afterthought] I was shocked when I first read that quote above, and may have overreacted, but only you will know.
<small>[ February 10, 2003, 03:57 PM: Message edited by: sdpatt ]</small>
Scott is absolutly right. The cams lobes are just slightly offset of the shim to allow the shim to rotate and provide even wear. shrug I wonder how that will effect the cam lobes as well. Also that will probably change your gap due to the fact the JB weld will harden and the shim will no longer touch the bottom of the bucket. Shame on you.
Slick_3.2
New Member
Doesn't the shim stay in one place, and the whole "bucket" turns. I re-checked the gap with the JB weld in there.
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