I looked a bit more for specifics on your '78 Chevette and it appears that there is a Quick Check hole in the cam sprocket that aligns with a hole in the front cover when the crank timing mark is aligned at #1 TDC. Later pictures call out a "lock bolt" where the '78 diagram says "Quick Check Hole" but you may find it's threaded to allow a bolt to hold the cam in position? Link to Pic - https://www.google.com/url?sa=i&url=...AAAAAdAAAAABAI