1971 w114 250 running smooth, engine shaking

[donlawson84]

just put together my 250, started it up and running great. but at idle the motor is shaking side to side, its a decent amount. as i rev it into higher rpm's, it smooths out. any input?

[Frank Reiner]

Originally Posted by donlawson84

just put together my 250, started it up and running great. but at idle the motor is shaking side to side, its a decent amount. as i rev it into higher rpm's, it smooths out. any input?

If you would be so good as to expand on the highly technical term "just put together", it will probably be helpful for folks on the forum!

You might sense that there is an inherent contradiction between "running great", and "shaking side to side".

[donlawson84]

just rebuild the head, left carbs on manifold, left distributer, crank and cam in same timing location for reassembly. im going to check the ignition timing next, not sure if that would cause that. seems to be idling fine, just rough.

manual calls for a stroboscobe to set timing, i searched pelican parts and looked online. does it need to be specifically for adjusting mercedes timing?

[donlawson84]

Found small air leak on rear carb mount, sealed that up but no difference in rough idle. checking timing, searching online and not finding too much info besides everyone lining up cylinder one to TDC.
these pics are where the motor is lined up, the cam gear has a mark, the bottom end looks a little off. any help would be great

[joshhol]

I can't see the mark on the cam gear as well as I can see what's on the cam tower. If the cam gear is lining up with the mark on the tower but the pointer on the crank is off, you may have skipped a tooth in the timing chain.

[donlawson84]

the cam pic is upside down, its a dot and a larger circle. they are lined up with the notch on the cam housing.
The crank pic shows a notch just past the pointer.

[donlawson84]

here is pictures from another mark on the cam gear, and where it lines up with the crank pointer

[Frank Reiner]

Cam timing/chain wear are well within limits. You're OK.

[BWhitmore]

A strobe timing light is a common type of timing light used on all types of engines. The timing light is connected to the battery for power and also to number 1 cylinder. When number 1 cylinder fires the light will flash. The idea is to shine the flashing timing light at the timing mark to ensure that the timing mark is aligned with the pointer. This is done with the engine running at idle speed. If the timing mark is not aligned with the pointer, the distributor should be rotated while the engine is running in order to align the timing mark. Most major auto parts stores have tool loan programs and they usually will loan out timing lights with a deposit.

[donlawson84]

as of right now i am concerned with the mechanical timing. i removed the head and worried i may have jumped a tooth when re installing the cam gear. once i am assured that it right, i will check the ignition timing.

[JMela]

I'd make certain your carburetors are both balanced and feeding an equal amount of fuel at idle.

[Mike D]

What assurance are you waiting for? Frank told you the mechanical timing is correct. Looks as though you have apx. 5 degrees of wear on the chain/sprocket. It is within acceptable limits.

[donlawson84]

well then tomorrow im gonna be putting the radiator back in and buttoning up. next step is to check ignition timing and carbs

[Mike D]

Double check your plug wires for correct firing order. Easy mistake to make. I've made this "oops" probably a hundred times.

Since you haven't replaced the radiator this means you haven't tested the engine under a load. It's not uncommon for a mis-wired firing order to "smooth out" when there is no strain on the engine.

[scotty b]

have you checked the mounts ?