just looked at a completely original 68z ,untouched car.The intake bolts are black phosphate. is this correct?
No, that is not right. All bolts were silver cad.
Jerry
The bolts on my low-mile '67 Z were not plated. I would guess they were supposed to be but maybe they were out of those bolts when the engine was assembled and they used the non-plated bolts. That sort of stuff happens from time-to-time.
-Jon
Flint-built Corvette engines with aluminum intakes used black phosphate plain hex bolts; commonly-seen headmarks on untouched original intakes are "A", "NAT", "UR", and "FP", although other have also been seen, and mixed usage on the same engine is common.
There are traces of silver cad on both of my survivor cars, the 67 Z (13,000 miles) and the early production 68 Z (23,000 miles). By pass fitting on the 67 has some orange paint on it and the 68 has no traces of orange overspray.
Jerry
THANKS FOR THE INFO GUYS.