What should compression be in a 12 valve? Got mine up and running after who knows how long and it's bad! Gonna check timing first but this thing won't start on it's own. Needs some spray to get it going. Once it does it's nothing but white smoke. So before I start putting money into this thing I'd like to be certain I have a solid motor first.

 

I just tested my 300K mile 96 12 valve and got 400-410 on all but one cylinder. I was told that 375-425 is acceptable but that consistency between cylinders is more important.

White smoke is usually a sign of slipped/retarded timing. Or a puked head gasket letting water in. Injector tips will show something other than soot if water is making its way into a cylinder.

 

Thank you for that! Truck has almost 300k. Hasn't ran in who knows how long. I just hope it is timing and nothing major.

 

Low fuel delivery system pressure will also cause white smoke.
http://www.cumminsforum.com/forum/94...-12-valve.html

http://dodgeram.info/tsb/1996/14-07-96.htm