Hi Joe:
Do your sources show the 3848904 dual, deep-groove water pump pulley being used on any 1966 or 1967 Corvettes, possibly the L79 when equipped with A/C but no power steering?
I have conflicting information about whether the L79 with A/C and no PS used the deep-groove pulley set consisting of the 3848904 on the water pump and the 3858533 on the crank, or the standard-groove pulley set consisting of the 3890419 on the water pump and the 3850838 on the crankshaft.
My theory is that when the L79 had A/C and no PS, it used the deep groove pulley set, and when the L79 had A/C and PS, it used the standard-groove pulley set.
Note that for an A/C car, the 3848904 deep-groove water pump pulley would be preferable to the standard L79 3770245 deep-groove pulley, since the smaller diameter of the 3848904 would spin the water pump and fan faster, as was customary for other A/C pulley sets of the period.
The justification for using standard-groove pulleys on this one L79 application is that in a configuration that required three belt grooves with the PS belt in the forward-most position, the PS pump pulley of a deep-groove stack-up would hit the frame rail where the frame kicks up right in front of the pump. The triple deep-groove stack-up is 3/8 inch thicker than the triple standard-groove stack-up, and clearance in the PS pulley area is very tight.
If, in fact, the L79 pulleys were changed to a standard-groove set *only* for the unique combination of A/C and PS, it would explain the need for the unique "HP" code associated with that combination. The standard-groove pulley set appears to use a different hub spacing on the water pump, as we discussed a few weeks ago.
I'm just trying to sort out the possible reasons for some of these little mysteries. I am finding that "pulley set engineering" is more complex than it first appears, and GM's thinking behind the various combinations they used may take some digging to discern.
Do your sources show the 3848904 dual, deep-groove water pump pulley being used on any 1966 or 1967 Corvettes, possibly the L79 when equipped with A/C but no power steering?
I have conflicting information about whether the L79 with A/C and no PS used the deep-groove pulley set consisting of the 3848904 on the water pump and the 3858533 on the crank, or the standard-groove pulley set consisting of the 3890419 on the water pump and the 3850838 on the crankshaft.
My theory is that when the L79 had A/C and no PS, it used the deep groove pulley set, and when the L79 had A/C and PS, it used the standard-groove pulley set.
Note that for an A/C car, the 3848904 deep-groove water pump pulley would be preferable to the standard L79 3770245 deep-groove pulley, since the smaller diameter of the 3848904 would spin the water pump and fan faster, as was customary for other A/C pulley sets of the period.
The justification for using standard-groove pulleys on this one L79 application is that in a configuration that required three belt grooves with the PS belt in the forward-most position, the PS pump pulley of a deep-groove stack-up would hit the frame rail where the frame kicks up right in front of the pump. The triple deep-groove stack-up is 3/8 inch thicker than the triple standard-groove stack-up, and clearance in the PS pulley area is very tight.
If, in fact, the L79 pulleys were changed to a standard-groove set *only* for the unique combination of A/C and PS, it would explain the need for the unique "HP" code associated with that combination. The standard-groove pulley set appears to use a different hub spacing on the water pump, as we discussed a few weeks ago.
I'm just trying to sort out the possible reasons for some of these little mysteries. I am finding that "pulley set engineering" is more complex than it first appears, and GM's thinking behind the various combinations they used may take some digging to discern.
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