I have a 85 351W From a F-150 pick-up which I have recently rebuilt.
During cam break in I had a drop in oil pressure from 40 to 20 psi half way through break in, it then even got to about 15psi I shut it down, I wasn't sure if it was the gauge or something else.
I changed the oil and filter the oil was pretty dark but didn't have anything really noticeable as damage.
After I'd changed the oil I also added another gauge to double check the one I was using I then reprimed the oil pump with my drill, it went to 40psi both gauges after running engine after about 5 minutes oil pressure started to drop again.
My engine has a Comp Cams camshaft with flat tappet lifters which are also Comp Cams I initially used Joe Gibbs break in oil which has the ZDDP additive in it, second time I used 5w30 with Lucas Oil ZDDP additive, can any body help me out? Thanks