67 L79 crankshaft pulleys differences
I was looking at part numbers on the pulleys today on a c60 L79 HT engine. The crankshaft pulley is a 385833 (judging manual states it is for a non c60 engine) and not the 3850838 pully. Does anyone know what the difference is? Different diameter? Deeper groove?
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Re: 67 L79 crankshaft pulleys differences
King------
The 3858533 is a deep groove pulley and is used only with a deep groove pulley set. The 3858533 is 6-5/8" OD. It's not designed for the use with any add-on pulley.
The 3850838 is a standard groove pulley and is used only with a standard groove pulley set. The 3850838 is 7-21/64" OD. It can be used with appropriate add-on pulleys (e.g. GM #3751232).
Deep groove pulleys cannot be used with standard groove pulleys and vice-versa. The difference in groove depth creates a difference in groove spacing that will result in mis-alignment if the deep groove and standard groove pulleys are mixed in a set.
In general, L-79 with C-60 used a standard groove pulley set.In Appreciation of John Hinckley -
Re: 67 L79 crankshaft pulleys differences
Interesting.....thanks Joe!
The mismatched set has been on the engine i know for the last 30 yearsComment
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Re: 67 L79 crankshaft pulleys differences
King------
I don't know how they got the pulleys to align. Do you know the other pulleys to be of the standard groove type? Does the car have added-on power steering? It's possible that some L-79 might have been built with a deep groove pulley set. I don't know how this could have been done since the A/C compressor pulley is designed for use with a standard groove pulley set but perhaps there is some way it can be done.In Appreciation of John HinckleyComment
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Re: 67 L79 crankshaft pulleys differences
Joe the water pump pulley is 3848904. Is this a set? Is it possible the judging manual has transposed numbers? Or am I read g it wrong?Last edited by King M.; October 20, 2015, 02:35 PM.Comment
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Re: 67 L79 crankshaft pulleys differences
King-------
The GM #3848904 is a deep groove waterpump pulley and is usually paired with the deep groove 3858533. However, I don't think this pulley set was used with C-60 L-79 applications.
Attached are photos showing the difference in the grooves between the 3850838 and the 3858533 crankshaft pulleys. This difference is what precludes their use with other pulleys of a different set.
DSCN3191.jpgDSCN3192.jpgDSCN3193.jpgDSCN3194.jpgDSCN3195.jpgDSCN3196.jpgIn Appreciation of John HinckleyComment
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Re: 67 L79 crankshaft pulleys differences
The timjg shows the 3848904 w/p pulley paired with the 3850838 c/s pulley but that would be a mismatched set. Does the deep groove pulley set use a different alternator belt than the standard groove pulley set?
this is a c60 only no n40Comment
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Re: 67 L79 crankshaft pulleys differences
King-------
I think there are going to be some revisions to the pulley tables in the next edition.
The deep groove pulley set does use a different alternator belt than the standard groove set. However, I believe the only difference is a slight difference in length.
What is the waterpump pulley installed on this engine?In Appreciation of John HinckleyComment
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Re: 67 L79 crankshaft pulleys differences
The water pump pulley is the 3848904. I installed the alternator and put the quanta repop belt for a l79 c60 only and the belt was too long. Alternator went to its adjustment limits. The quanta belt fit below the top of the vee in the pulley.
wonder now if I should get a alternator belt for a non c60 perhaps it is a shorter belt. Would that count against me in judging?Last edited by King M.; October 20, 2015, 10:14 PM.Comment
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Re: 67 L79 crankshaft pulleys differences
King------
I've heard of lots of fitment problems with reproduction belts.
The GM #3848904 waterpump pulley and 3858533 crankshaft pulley are not the ones that GM originally specified for your application. They were not specified in either PRODUCTION or SERVICE. In addition, I do not understand how these could be made to align with the a/c compressor pulley which was designed for use with the standard groove pulleys. Is your a/c compressor belt slightly misaligned with the waterpump and crankshaft pulley grooves? If it came from the factory this way, I would say it's some kind of factory mistake. However, I can easily see how such a mistake could have occurred.In Appreciation of John HinckleyComment
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Re: 67 L79 crankshaft pulleys differences
image.jpgimage.jpgJoe here is the belt installed on the ac compressor the compressor may move back slightly when all is tightened up but I don't think it will move much. When you sight down both belts they are straight from alt and ac compressor to the two pulleys.Comment
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Re: 67 L79 crankshaft pulleys differences
King------
I would say that either the pulleys were changed at some point or this was a factory mistake.
While the A/C and waterpump pulleys may appear to be aligned, the misalignment would be slight and might be hard to detect visually.
What I know for sure is this: there was no deep groove a/c pulley and the a/c pulley was designed to work with the standard groove pulley set. If the a/c pulley was designed to align with the standard groove pulley set, then it could not align with the deep groove pulley set. However, the alignment difference would be slight. Still, it's not the kind of thing that GM engineering would ever have approved of.In Appreciation of John HinckleyComment
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Re: 67 L79 crankshaft pulleys differences
Joe was there a deep groove pulley for the alternator?Comment
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Re: 67 L79 crankshaft pulleys differences
Alternator pulley is a 3909817 on a 61 amp 1100750 alternator....Comment
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