With the clamp removed, the distributor lifted-out with a direct upward tug. | 
The next step before installing the new MSD distributor was to set the Y-block to its initial timing. First we removed the valve cover on the right bank to access a view of number 1's intake and exhaust valves. | 
Then, with all of the spark plugs removed, we turned the engine over with a socket attached to the bolt on the harmonic balancer until the TDC timing-mark on the harmonic-balancer pulley aligned with the timing pointer. |
We used a disposable drinking straw to drop into the cylinder and felt it rise to TDC to double-check the engine was at top dead center. | 
Initial timing means the engine is in its firing cycle. To establish that the engine is not 180 out of time, the intake and exhaust valves must be completely closed. Since a Y-block motor has solid lifters, it was easy to confirm that we were on the money by spinning the pushrods in our fingers. | 
The MSD Y-block distributor comes with a cast-iron gear, and should only be used with a cast-iron solid-lifter (flat-tappet) camshaft. It's a pretty safe bet that one is dealing with a cast-iron camshaft in their Y-block. If someone is unsure, the dilemma can be solved by installing an optional bronze gear from MSD, which suits either steel-billet or cast-iron camshafts. It was essential to coat the gear liberally with Comp Cams assembly lube. |
If the oil-pump drive isn't centered, it will be difficult to drop the new MSD distributor completely in. With one screwdriver we packed heavy (thick) grease all around the oil-pump drive (rod) while we used another screwdriver to keep the rod centered. | 
With the oil-pump drive held in place with the thick grease, our next step was to carefully drop the MSD distributor straight down, meshing with the helical-cut gear on the camshaft and then all the way home with the oil-pump drive rod fully inserted into the MSD distributor. | 
The location for number 1 can be placed at any of eight terminals on the MSD distributor cap. We used a piece of 3M tape to mark number 1 and then installed the MSD distributor cap. |