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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53153
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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I have a 68 280 sl were are the timing marks on the crank?

Customer Question

hi i have a 68 280 sl were are the timing marks on the crank?
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi, are you trying to set the ignition timing?

Customer: replied 1 year ago.
no i replaced the head and trying to find tdc on the crank for the timing chain
Expert:  Marty replied 1 year ago.

Ok, is the head back on the car already? Are the rocker arms installed?

Customer: replied 1 year ago.
it is
Expert:  Marty replied 1 year ago.

Rocker arms off?

Customer: replied 1 year ago.
No it's not do I need them off
Expert:  Marty replied 1 year ago.

I'm just concerned that you might have bent the valves when you set the head on. Are the valves of #1 cylinder closed? Was the #1 piston up when you set the head on?

Customer: replied 1 year ago.
Well it wasn't bolted down yet and couldn't find the marks on the crank
Expert:  Marty replied 1 year ago.

I'm assuming that the crank pulley is still on the crankshaft. The marks are all the way in against the block on the innermost crank balancer. There are two sets of marks on the balancer. You use the ones that are closest to the motor. The pointer is on the right side upper at about the 1 o'clock position as you are facing the motor.

Customer: replied 1 year ago.
But if I have that on 0 #1 cyl is not tdc
Expert:  Marty replied 1 year ago.

You have to be careful that you don't run the valves into the pistons and bend the valves. When installing the head you should set the cam on the timing mark with the lobes of #1 cylinder pointing up. The #1 piston should be at TDC when installing the head. You can back the crank up about 20° just to be sure nothing hits when you set the head on then rotate the crank to TDC and install your chain.

Expert:  Marty replied 1 year ago.

Someone may have installed the balancer incorrectly. Can you easily remove the head and visually put the piston at TDC?

Expert:  Marty replied 1 year ago.

Do you see the two sets of marks on the crank pulley?

Customer: replied 1 year ago.
I set the most inner set of marks to zero
Customer: replied 1 year ago.
the head is off at this moment
Expert:  Marty replied 1 year ago.

Ok, when you put #1 piston at TDC you will need to make your own reference mark on the crank pulley.

Expert:  Marty replied 1 year ago.

Check the outer marks and see if they line up but most of the early SL's used the inner marks.