silver small blocker

So I just had a head gasket replaced due to a leak on cyl 7. My mechanic told me the engine had a little sludge so he changed the oil out twice after running it for a while. After 2 hours of driving after the repair the lifters started making a lot of noise. The mechanic tells me no/little oil is making it to the cam and valves but the oil pressure is fine. Any thoughts on where the clog/problem might be and how to clear it without a complete tear down? The engine is from a 97 Z 28 w/ 6 speed and has 135K on it without prior problems. I bought it new.

zman1969

iTrader: (91)

if the head gaskets had been leaking internally and intermixing with oil - that can tear up your bearings and it would also affect your oil pressure some. small blocks arent known to do that but maybe thats why he changed the oil twice? -intermix is bad for bearings