I have turned into the Datsun tutor for a young lad(17”) Alex that has bought a 81zx project. The motor was half apart and the guy he bought it from was not the wrench on this car , just an owner . Anyways , the block and head were together in the car , but no induction or exhaust - that was all laying in the car . Dirty valve train like the valve cover was off for a long time . It’s been sitting for years . Took the head off to inspect and clean . Mating surface was flat . Cam is a CWC core and seems to be a stock replacement . Engine did turn over fine .
He brought me the head and I broke it down to be cleaned and to do anything else necessary for him to have a runner . I sent it to the machine shop and told them to check it out . Valve tips looked molested already like someone already did a valve job.
Got it back from the machine shop and they had taken .007 off the mating surface to clean up pitting and did a valve job . I started reassembly to check wipe patterns and I couldn’t get the cam in . I admit that when I took the head apart I did the quick and easy and removed towers and cam all at the same time , so I probably missed the cam was binding . Got out my straight edge out and found the top surface out of flat . This is where I realized I was dealing with a previously warped head . Shame on me and the machinist for not checking for time . In all fairness , who know if this shop ever saw an old Datsun head .
What to do now . The kid had.230$ in this head that the cam won’t turn . Took it back and head top surface skimmed . He said he took .017 off the middle and .002 off the sides? Not sure how he come up with that , but it’s flat and the cam turns perfectly . A quick wipe check showed the wipe pattern that will work , actually pretty well centered . I imagine that was because they dressed the tips of the valves . I also questioned the tipping of the valves and they assured me that they didn’t go too far which would compromise the hardness level.
So what happens to the combustion chambers ? It’s been shaved , so what’s the CR now ? How far off will they be from each other since the head had been warped ? See my findings . I guess I have some grinding to do