| Frank Reiner |
12-03-2018 04:39 PM |
Quote:
Originally Posted by DHartman66
(Post 3866719)
I'm working on a 1984 380SL and have changed the timing chain and guides. Upon replacing the sprocket to the cam, I noticed that the TDC marks on the cam did not match the 0 TDC on the vibration damper. I had assumed that I had somehow let the chain slip on the cam, so I removed the rocker arms, reset the cams to TDC with the vibration damper and reinstalled the rocker arms. To my shock, I found that the TDC for the #1 and #6 were not at 0 TDC but at 270 degrees; 90 degrees off! I verified that #5 and #3 were at TDC at 0 TDC, so the million dollar question is how can the crank get 90 degrees off?
|
DH:
What procedure did you follow to replace the chain? You have used the singular in speaking of replacing the "sprocket to the cam"; did you remove only one sprocket from its cam? Which side?
If you had removed cam followers (rockers) on both sides as a first step, the cams can be turned freely when the chain is removed.
In such a case, timing can be restored by first setting the crank to #1 TDC by feeling for piston position thru the spark plug hole. Then, set the cams w/ sprockets in alignment with their respective timing marks. If the chain has been fed in, the sprockets can be slid off the cams, and the chain hooked over the sprockets, and the sprockets returned to the cams. With the chain on the sprockets, and the sprockets on the cams but not over the keys, check for alignment of the keyways to the keys. It may be necessary to re-index the sprockets in the chain to obtain simultaneous alignment of crank at TDC and the cams on their marks.
When all three marks are aligned, and the tensioner reinstalled, then reinstall the followers. |
