check timing chain stretch?

[merrill]

so, tomorrow I plan to check the valves on my 66 230 sl.  while I have the valve cover figured I would check a few things.

the bbb has the instructions on how to do this for the 190 d and 200d
page 05 -20/1.

how do you check the stretch on the 66 230 sl?

thanks
matt

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[al_lieffring]

As the timing chain wears (stretches) the valve timing becomes slower (after TDC). 4 or 5 degrees is fairly normal. Moving the chain one tooth on the timing gear chages the timing 18deg. In your other thread you say the timing is within 1 degree so that would indicate the chain has almost no wear.

Al  :O)

113-042-10-014715
built 11 Jan 66
904/396 blue, Ivory Tex
condition- rust bucket

[merrill]

Al,
so, torqued the head and adjusted all the valves today.
then double checked the engine timing.  still about 6 deg atdc.

The car idles super smooth.   I mean really smooth.  my buddy came over for a while and commented that he could barely feel the motor vibrations when he put is hand on the drivers rear fender.



Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[al_lieffring]

Matt.

The 4 or 5 degree ATDC that I was referring to is the crank position when the cam timing marks line up. Not the more precise cam opening spec, given in the BBB.
It sounds like you are in good shape.

If a chain was so worn that it had to be advanced 18deg to the next tooth on the sprocket(yes, I have seen them that bad) the tensioner would be past it's travel limit and the chain would not lay flat on the sprocet.



113-042-10-014715
built 11 Jan 66
904/396 blue, Ivory Tex
condition- rust bucket

[merrill]

Al,
so, now I am confused.  pls confirm If I have done this procedure correctly.

1. set crank at 0, cam sprocket marks are lined up, distributor rotor is pointing at #1.

2. continue rotating crank till #1 intake opens .4mm

3. measure crank, which on mine is 6 deg atdc

thanks

Matt
66 230 sl - "white"
78 300 D - Blue
98 C230

[Benz Dr.]

I look at the marks on the cam gear. When they are lined up then I look at where the marks are on the crank. Anything more than 3 degrees is pretty worn but even a new chain may not correct this. If the gears are heavily worn no amount of testing will give you an acurate reading. I always replace the crank gear during and engine rebuild.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061