Got a 478...

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Starting to look like an engine again.

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Another piece of the puzzle is the front pulley. I wrote about this in the 65 GMC build thread: I wanted to originally use the 478 pulley. However, it looks out of place, and it didn't fit after all. You would end up with an overdriven water pump as well.

Therefore modification of the 305 pulley is in order. I designed an adapter plate that can be used to bolt on external weights. It mounts onto the bolts holding the pulley in place, and nuts are used to fixture it. I am also working on a balancing fixture to determine the exact weight needed. The 478 pulley serves as a guide here.

Another 'upgrade' that I'm doing to the 305 pulley is the addition of the tapered sleeve, found in the bigger pulleys. This is a copper sleeve, that tightens onto the crankshaft when the front crankshaft bolt is tightened. It is easily added to the 305 pulley by machining a 15-degree taper into the bore.

More to follow.

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Balancing fixture in action. I had to add a 2mm thick steel plate to the adapter. The 2mm plate followed the same contours as the underside of the adapter. As you can see, I had to remove as much material as seen in the picture to recreate the balance. I also had the timing indicator and adapter and weight zinc plated to recreate the factory look. All bolts were secured with LocTite and the front pulley was installed and torqued to spec. The tapered sleeve helps it stay rigid to the crankshaft, which is a worthwhile addition with the added weight.

Since we're nearing the end of the engine build the following posts will be continued in the 65 GMC build thread, where we install the engine.

Any comments are, of course, welcome