From a previous post:
I hope someone can help me. I have a 1985 Dodge 150 Royale with a slant six motor. As it turns out the previous owner changed motors and the one that is in seems to be from the late 1970's (the valve cover is anyway). Here's the dilemma. The motor kept bogging down so I went through everything external (carburetor, distributor, plugs, cap, rotor and wires) kept skipping time so I replaced the timing chain. Here's where the dilemma comes. When I went to replace the timing chain, the timing marks were off, actually 180 degrees off. In both the chilton's manual and the Haynes manual, the timing marks are supposed to face each other. However before I removed the old timing chain the crankshaft mark was facing up like it is supposed to, however the camshaft mark was on top away from the crankshaft. The marks were in line with each other, just not facing each other. Well I kind of got prematurely excited figuring that was why the motor wouldn't run properly. So I followed the instructions in the manual and lined up the timing marks facing each other. Now the motor won’t run at all. Has anyone ever experienced this?
Before I removed the old timing chain I did crank it over, no matter how many times I cranked it, the timing marks never matched up except as described in my initial post. Also tried moving the rotor 180. HMMMM.

I think by turning your cam 180 you threw the distributor off by 180.

have resolved to taking the timing chain cover off and starting from scratch. Probably my oversight. Thanks To all that responded. I would also like to add that this is a facinating forum for anyone who needs information on a slant six engine. One of the best forums I ever been to. You have my contribution