Hi,
Do you run a mechanical fuel pump? if so then the cam eccentric or bolt could be loose under the timing cover. There is also a cam 'walk' plate there at the front of the cam with 2 bolts holding it on. The only other thing attatched to the cam is the distributor, do you have the proper cam gear on it for a hydraulic cam, it's different than the roller cam gear.
Good Luck,
Perry.
