How to Rebuild a Corvette 454 Engine - Part 10 continued

So, with the heads and guide plates installed I can now start assembling the valve train. Before installing the new pushrods I first thoroughly cleaned each one and then wiped them down with a lightly oiled rag.

Installing pushrods is pretty simple - just drop them into place and double check that each one is seated properly in the lifter.

Next I installed the rocker arms and tightened the rocker arm nut to zero lash using the method I described in my last update.

Once at zero lash I turned each nut and additional one-half turn, installed the locking nuts and tightened them down. In the photo below you can see that I've also applied a bit of moly grease to the tip of each pushrod and valve stem to reduce wear during initial startup.

Uh-oh! After I got about half way done I noticed that my rockers weren't centered properly over the valve tips. I don't want to be replacing the valve guides any time soon so I'll have to fix this. The problem was that, although one rocker arm was centered over the valve tip, the other was quite a bit off center. This meant that each guide plate needed to be modified to properly establish the valve train geometry.

Here's a close-up photo of one of the rockers. As I mentioned, the roller tip should be centered over the valve tip to prevent side loading of the valve guide. That's certainly not the case here.

Apparently Airflow Research heads are notorious for having this problem. It's not a big problem, but a pain to fix nonetheless. Anyway, simply shifting the guide plate back and forth didn't do the trick. Instead, I had to disassemble the valve train, remove the rocker studs and guide plates and then do some modification work to the guide plates. Using a Dremel tool I enlarged the holes for the rocker arm studs just a bit. Next I either flattened or increased the camber of the center portion of the guide plate as needed to get the proper rocker arm alignment. It took numerous tries to get each one right, but after a several hours I managed to get the rocker arm geometry dialed in pretty good.

Here are the rocker arms after adjusting the guide plates and getting everything reassembled. At this point I've established that the valve train geometry is correct by 1.) centering the rocker movement in the left-right direction via. pushrod length and 2.) centered the rocker arm movement in the front-back directions by adjusting the guide plates as necessary. I should also note that during the valve train assembly I checked that the valve springs were not binding at full lift, that there was sufficient clearance between the rocker arms and valve spring retainers, and that the pushrods did not rub against anything when the engine was turned over.

In the end this whole process took a while longer than I had planned. Not only is there a lot to check, but getting everything set up properly is time consuming. In the end it will be worth it though!

Below are a few photos of the motor with the heads and valve train fully installed.

Next on the to-do list is getting the intake in place and then bolting on parts such as the carburetor, water pump, alternator, etc. It won't be long before I have this motor on a dyno and we all get to see what it can do!

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