Rare Pulleys

[Larry P.]

Re: Rare Pulleys

Neal, I know the question isn't for me, but thought I'd answer anyway. You and Loren are both correct.
In your example, the CS pulley is the drive pulley. So since the diameter of the CS pulley remains constant, increasing the AC pulley diameter will result in it spinning at a lower RPM.

[Joe R.]

Re: Rare Pulleys

Yes, the 346290 and 14023153 are standard-groove PS crank pulleys that nest with the deep-groove dual 3858533 crank pulley. So, in this respect, they are functional alternatives for duplicating the rather odd 1965 combination a standard-groove PS crank pulley used in combination with a deep-groove dual crank pulley.

As noted in my previous posts, the 3860457 PS pump pulley comes very close to lining up correctly with the above crankshaft pulley combination. I'll have a bit more info on this after I get another sample of the 3860457 (my current sample does not run true).

Okay, it took me a while to get back to this after I got a non-bent sample of the 3860457 pulley.

Attached is a photo of a mock-up I did on a 327/300 engine I have on a stand in the garage. Do not be put off by the small balancer on this engine. The front face of both the 327/300 small balancer and the L79 327/350 large balancer are both in the exact same place with respect to the block (I am 100% certain of this because I have previously compared both balancers on the bench). The back face of the larger balancer simply extends farther back toward the block.

The crankshaft pulley arrangement in this photo is a dual deep-groove 3858533 with a single standard-groove 346290 add-on pulley for power steering. If you look carefully you can see that the outermost groove on the crank is slightly narrower than the inner two grooves on the crank. The pulley on the PS pump is a standard-groove 3860457.

Neither of the PS pulleys in this photo were used for production on the '65 L79 with A/C and PS, but the actual part numbers that were used (3827843 add-on crank pulley and 3868892 PS pump pulley) are had to find, especially the 3868892 PS pump pulley.

What made the '65 L79 with A/C and PS configuration unusual is that GM used deep-groove pulleys for everything but the PS pulleys, which were standard-groove. It was very unusual for GM to mix the two pulley types on the same car. So, if an alert judge is looking at a '65 L79 with A/C and PS, they will be expecting to see standard-groove pulleys for the power steering only. And, they will expect the PS pulleys to line up properly.

For those unlucky owners that don't have the correct standard-groove pulleys for their power steering, I put together the combination in the photo to show how close you can come using other GM pulleys. By my measurements, the pump pulley is about .025" too far back, but it's pretty hard to tell. For those who seek perfect alignment, a bit of discreet shimming on the pump can easily add the required .025".

At present, this is my best shot at coming up with something that closely resembles the unusual original configuration that used standard-groove pulleys that are now very difficult to find.