Rocker Shafts, Pushrods, and Valves (5)

5 hours

The next step in our journey outwards on the engine was the rocker shafts.  The little mounting blocks have a gap on one side, and the instructions say to place install the shaft with the gaps facing down.  That didn't make sense to me at first, until I realized I could just remove the bolt from each end of the shaft and flip the blocks over.  Then I was able to install the shaft correctly.

In order to place the little swivel pads slightly off-center on each valve stem, I ended up having to use two of the square shims per mounting stud.  Once I got that figured out, I used the pushrod length tool to determine the correct pushrod length for the left side.  Using that as a template, I cut four pushrods to the appropriate length.  I just used a hacksaw to cut them and then filed and deburred the ends.  The little tips were pretty hard to insert.  I ended up heating the end of each pushrod quite a lot with a heat gun, and then hammering the tips on with a plastic hammer.  I'm confident they will definitely never fall out!

Next I put a pushrod in each tube, reinstalled the rocker shaft, and torqued it down.  Then I set the valve clearances per the manual.

Finally I installed the valve cover with its cork gasket.

The other side was not as easy!  It took me a good two hours of trial and error with the square shims, swapping around the round shims on the rocker shaft, and swapping rockers around to finally get all four adjusters lined up properly with the valves.

Then I used the pushrod tool again, on the #4 intake valve, to determine the required length, and I cut all four pushrods to that length.  However, when I assembled everything, I found that both pushrods on cylinder #3 were slightly too long.  I spent a bunch of time investigating how this could be, and I finally narrowed it down to just slightly inconsistent rockers and adjusters between the two cylinders. 

All four pushrods line up, so there's nothing wrong with the lifters:

And all four valves are flush with each other:

So that pretty much isolates the rocker shaft as the source of the differences:

Using the length tool I figured out cylinder 3 just needs pushrods about 1/8" shorter...  It's not much but it's enough to prevent me from backing out the adjusters far enough to set the valve clearances!  I've got some new pushrods on the way and I think that will take care of that.