'72' Merc 650 timing issue

[fmfmedic]

Hi; I've been working on a friends motor, a 1972 Merc 650 4 cylinder. It ran fine until the corroded distributor wires shorted out at the distributor. Put in a new distributor and used the old cap. Did not remove the flywheel or any other components. Now the TDC mark lines up with the distributor when number 3 cylinder is at TDC instead of number one. With number one at TDC, the flywheel is 1/4 turn BEFORE the timing mark. At this point I am thinking of pulling the flywheel and repositioning it, but I shouldn't have to since it was running well before. Could I simply change the wire positions? Or is it possible the distributor cap is rotated? I didn't think there was enough play in the wires to do that. Any advice would be helpful. I do have the manual, but it doesn't cover this.

 

[CharlieB]

Re: '72' Merc 650 timing issue

Two piece flywheel and you took it apart rather than pull the hub off the crank?

It's real easy to get the outer half out of time from the crank that way.

Turn the motor so #1 is at TDC, unbolt and reposition the outer half of the flywheel. Recheck your TDC mark and the distributor pulley alignment mark.

 

[fmfmedic]

Re: '72' Merc 650 timing issue

As I said, I didn't remove or loosen anything other than the distributor. Never touched the flywheel. I did, however take off the spark plug wires in order to make room to remove the distributor. They may have been out of order so somebody could time the thing to number three cylinder.

I'll remove the eight bolts, move the outer flywheel and reset the timing. Sounds a lot easier than buying and using a flywheel puller! Plus, it will set the timing to match the book.

 

[fmfmedic]

Re: '72' Merc 650 timing issue

OK, I set Number 1 to TDC according to a dial guage, moved the flywheel to TDC and reconnected the spark plugs in order. I'll complete the timing when the owner gets back to town and can help. This engine is not a '72' by the way. Double checked the SN and it's a late 1971, and this manual starts with the 1972 model. No help there. No wonder it's almost identical with my 1968.

Thank you CharlieB, for your help and advice