P.S.Questions 65 350hp w A/C

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

All-------


When you get right down to it, there really weren't all that many power steering pump and crankshaft pullies ever used on 63-74 Corvettes with small blocks.

Power Steering Pump Pullies:

GM #3770509-----stamped steel, 1 groove, standard groove pulley, 5-47/64" OD, "pancake" style pulley, MUST BE DRIVEN FROM OUTERMOST GROOVE OF THREE GROOVE PULLEY SYSTEM;

GM #3868892-----stamped steel, 1 groove, deep groove pulley, 5-23/32" OD, "pancake" style pulley, used only for 65-66, MUST BE DRIVEN FROM OUTERMOST GROOVE OF THREE GROOVE PULLEY SYSTEM;

GM #3834720-----cast iron, 1 groove, deep groove pulley, 6-1/8" OD, "drop-down" style pulley, MUST BE DRIVEN FROM OUTERMOST GROOVE OF TWO GROOVE CRANK PULLEY SYSTEM.

Crankshaft Pullies:

GM #3755820-----I believe this is a 1 groove pulley used for mostly C1 applications but also used for some early C2

GM #3747479-----stamped steel, 2 groove, standard groove, 6-5/8" OD

GM #3744043-----same as GM #3747479

GM #3858533-----stamped steel, 2 groove, deep groove pulley, 6-3/4" OD; used 1965-80

GM #3766987-----same as GM #3858533; used 63-64

GM #3850838-----stamped steel, 2 groove, standard groove, 7-21/64" OD;

GM #3911013-----stamped steel, 2 groove, standard groove, 7-47/64" OD; used for 1969-74 small blocks with C-60;

GM #3929697------cast iron, 2 groove, deep groove, used only for a few 1970-72 ZR1;

GM #3751232------stamped steel, 1 groove, standard groove; "add-on" pulley used for power steering driver;

GM #3827843------stamped steel, 1 groove, deep groove, "add-on" pulley used for power steering driver; 1965-66 SHP with C-60 and/or N-40

[Joe R.]

Re: P.S.Questions 65 350hp w A/C

I guess I'm way out in left field - I only know how to measure by using a ruler, tape measure or other primitive devices. Are we saying that there is another way to measure "deep" pulleys other than from the bottom to the top?

Hi Loren:

The difference between standard-groove and deep-groove pulleys is usually easy to see if you put one of each type side by side.

I believe you said you have a 533 dual crank pulley, which we know is deep-groove. If you put your add-on PS crank pulley or the PS pump pulley groove next to the 533 grooves, it should be fairly clear whether the grooves on the PS pulleys are about the same size as the ones on the 533, or are somewhat less wide and less deep.

[Joe R.]

Re: P.S.Questions 65 350hp w A/C

Joe------

The 1975-E80 power steering pump pulley was GM #346289. The E80-82 pulley was GM #14023175. The 14023175 replaced the 346289 for SERVICE after 1981 so the 14023175 is functionally interchangeable with the 346289. What the difference is between these 2 pullies I do not know. I believe that both are 5.72" OD, though.

The 14023175 remains available from GM to this day.

The above-referenced pullies cannot be used on a 1963-74 Corvette unless a 75+ pump is also used. The 75+ pump differs from the earlier in 2 basic ways:

1) The shaft is straight, non-tapered and designed for an interference fit on the pulley with no retaining nut used. This is the feature which necessitates the use of the above-referenced pullies;

2) The reservoir is a "one piece", "tear-drop" shaped with no ovoid, welded-on filler neck.

Hi Joe:

Thanks for pointing out the important difference in the 1975+ power steering pump shafts. I knew there had been a change somewhere along the way, but I did not know when it occurred.

Clearly, this means that no 1975+ pump pulley pulley can be fitted to a pre-1975 pump. So, the field of possible candidates is limited to 1963-74.

[Tony S.]

Re: P.S.Questions 65 350hp w A/C

Hello Joe, et al.

I have a '65 L79 with N40. My 3858533 crank pulley lines up perfectly with my 3834720 cast power steering pulley. Since my car does not have C60, I can't comment on a '65 L79 car with N40 and C60 since a car with those options requires a difference power steering pump pulley (steel 3868892 pulley). I believe James West has a '65 L79 car with both N40 and C60.

This discussion has been very helpful even though it has wandered a bit from the original question.

Mark Gorney's chart was really helpful. Mark, I hope you don't mind me publishing this list in the Kansas City Chapter's newsletter.

Thanks for everyone's input.
Best,
Tony

[Joe R.]

Re: P.S.Questions 65 350hp w A/C

All-------


When you get right down to it, there really weren't all that many power steering pump and crankshaft pullies ever used on 63-74 Corvettes with small blocks.

Power Steering Pump Pullies:

GM #3770509-----stamped steel, 1 groove, standard groove pulley, 5-47/64" OD, "pancake" style pulley, MUST BE DRIVEN FROM OUTERMOST GROOVE OF THREE GROOVE PULLEY SYSTEM;

GM #3868892-----stamped steel, 1 groove, deep groove pulley, 5-23/32" OD, "pancake" style pulley, used only for 65-66, MUST BE DRIVEN FROM OUTERMOST GROOVE OF THREE GROOVE PULLEY SYSTEM;

GM #3834720-----cast iron, 1 groove, deep groove pulley, 6-1/8" OD, "drop-down" style pulley, MUST BE DRIVEN FROM OUTERMOST GROOVE OF TWO GROOVE CRANK PULLEY SYSTEM.

Crankshaft Pullies:

GM #3755820-----I believe this is a 1 groove pulley used for mostly C1 applications but also used for some early C2

GM #3747479-----stamped steel, 2 groove, standard groove, 6-5/8" OD

GM #3744043-----same as GM #3747479

GM #3858533-----stamped steel, 2 groove, deep groove pulley, 6-3/4" OD; used 1965-80

GM #3766987-----same as GM #3858533; used 63-64

GM #3850838-----stamped steel, 2 groove, standard groove, 7-21/64" OD;

GM #3911013-----stamped steel, 2 groove, standard groove, 7-47/64" OD; used for 1969-74 small blocks with C-60;

GM #3929697------cast iron, 2 groove, deep groove, used only for a few 1970-72 ZR1;

GM #3751232------stamped steel, 1 groove, standard groove; "add-on" pulley used for power steering driver;

GM #3827843------stamped steel, 1 groove, deep groove, "add-on" pulley used for power steering driver; 1965-66 SHP with C-60 and/or N-40

Hi Joe:

Thanks for this excellent summary. Aside from our ongoing discussions about the 1965 configuration, this seems to confirm that with the possible exception of 1965, GM never installed a full deep-groove pulley set on 1963-74 Corvettes that were equipped with A/C *and* PS.

This is one of the interesting conclusions I had reached during my more limited research on C2 pulleys. It seemed unusual that GM would not use deep-groove pulleys on just this one configuration of SHP engines (A/C and PS together) that would otherwise have had deep-groove pulleys installed. My theory, as mentioned earlier, is that a full, triple deep-groove pulley set would place the PS pump pulley too close to the frame rail to meet GM's requirements for clearance tolerance stack-up.

From the earlier comments posted in this thread, it is not clear to me whether the two 1965 PS pulleys (3827843 add-on and 3868892 pump) were standard-groove or deep-groove. I think Mark Gorney may have described then as standard-groove based on his reading of the drawings. Hopefully Loren will post soon after he has looked at the 3868892 that he has in-hand.

[Mark G.]

Re: P.S.Questions 65 350hp w A/C

Anthony -

Yes, by all means; that's why we do these activities. I have dibs on the "Restorer" article(s). Email me for an updated chart; this discussion improved the data. Include the format you will need.

Mark

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

Hi Joe:

Thanks for this excellent summary. Aside from our ongoing discussions about the 1965 configuration, this seems to confirm that with the possible exception of 1965, GM never installed a full deep-groove pulley set on 1963-74 Corvettes that were equipped with A/C *and* PS.

This is one of the interesting conclusions I had reached during my more limited research on C2 pulleys. It seemed unusual that GM would not use deep-groove pulleys on just this one configuration of SHP engines (A/C and PS together) that would otherwise have had deep-groove pulleys installed. My theory, as mentioned earlier, is that a full, triple deep-groove pulley set would place the PS pump pulley too close to the frame rail to meet GM's requirements for clearance tolerance stack-up.

From the earlier comments posted in this thread, it is not clear to me whether the two 1965 PS pulleys (3827843 add-on and 3868892 pump) were standard-groove or deep-groove. I think Mark Gorney may have described then as standard-groove based on his reading of the drawings. Hopefully Loren will post soon after he has looked at the 3868892 that he has in-hand.

Joe-----


I have an NOS GM #3868892 but my back hurts just thinking about lifting and going through all those parts group 6 tote bins to find it.

[Scott S.]

Re: P.S.Questions 65 350hp w A/C

Joe-----


I have an NOS GM #3868892 but my back hurts just thinking about lifting and going through all those parts group 6 tote bins to find it.

Lift with your legs, Joe

[Joe R.]

Re: P.S.Questions 65 350hp w A/C

Joe-----

I have an NOS GM #3868892 but my back hurts just thinking about lifting and going through all those parts group 6 tote bins to find it.

Hi Joe:

In an earlier post, Mark Gorney said that in the GM drawings, standard-groove pulleys were always specified using a 5/16 (.3125 inch) diameter round pin seated in the groove, while deep-groove pulleys typically used a 7/16 (.4375) round pin.

In the drawing Mark posted for the 3868892 pulley, the pin is .3125 inches. So, by this inference, the 3868892 would be a standard-groove pulley.

The pin diameter is not visible in the partial drawing that Mark posted of the corresponding 3827843 add-on pulley, but I suspect that the groove type would match the 3868892.

In any event, perhaps you can hold off on digging out your NOS 3868892 pulley. If I recall correctly, Loren Lundberg said he has one that he removed from his 65. I'm hoping Loren will be able to compare the groove width to his 533 crank pulley and tell us what he finds.

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

All-------


OK, I "bit-the-bullet" and dug out an NOS GM #3868892 pulley. I got lucky; I found the pulley in the third group 6 tote-bin and there were MANY more to go through if I did not find it. You got lucky, too, because if I had not found it by the 5th or 6th bin, I would probably have given up and "washed my hands" of the whole deal.

Anyway, it turns out that the 3868892 pulley is, in fact, a standard groove pulley so that means that the ONLY deep groove pulley used for 63-74 small block Corvette power steering pumps was the cast iron, "drop down", GM #3834720.

This 3868892 pulley is interesting and after looking at it for the first time in about 10 years I recalled what the primary difference is from the much-more-common GM #3770509: the location of the mounting hub is considerably different between the 2 pullies. This would result in the 3770509 seating on the shaft at a location that is 0.44" closer to the pump than the 3868892. Although there are other design features which differ between the 2 pullies, this is the only real FUNCTIONALLY-RELATED difference. Although GM P&A specs show the pullies to be slightly different in OD, the as-measured OD is exactly the same between the two pullies----5.74".

Another interesting thing I noted is this: this 3868892 pulley appears to have been manufactured no later than about 1966. The 3770509 pulley pictured was manufactured in late 1983 or earlier and is labeled as "Made in Canada" on the GM box. However, both pullies have a "P" stamped on the face. I presume the "P" to represent the manufacturer. So, while manufactured 17+ years apart and, possibly, in different countries, both were apparently manufactured by the same source.

I'm including photos of the pullies. I took quite a few photos and since there seems to be a lot of interest in this pulley and the difficulty for others to obtain, I'll post them all in subsequent posts.

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

More photos of the pullies:

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

And even more and, by the way, in case anyone does not understand me by now, these pullies are NOT FOR SALE:

[Scott S.]

Re: P.S.Questions 65 350hp w A/C

Thanks Joe!

[Joe L.]

Re: P.S.Questions 65 350hp w A/C

All------


For the sake of completeness, I'm including photos of the cast iron, "drop-down", GM #3834720 power steering pump pulley. This is the only other pulley originally used for any 1963-74 small block Corvette with power steering.

This pulley seats on the shaft at a dimension 0.41" closer to the pump than the 3770509 and 0.85" closer than the 3868892.

The third photo in the series shows a comparison between the groove on the 3834720 pulley on the left and the 3770509 on the right.

And, that's it! Pictured here and above are all of the power steering pump pullies ever used on a small block Corvette from 1963 to 1974.

[Joe R.]

Re: P.S.Questions 65 350hp w A/C

All-------


This 3868892 pulley is interesting and after looking at it for the first time in about 10 years I recalled what the primary difference is from the much-more-common GM #3770509: the location of the mounting hub is considerably different between the 2 pullies. This would result in the 3868892 seating on the shaft at a location that is 0.44" closer to the pump than the 3770509.

Hi Joe:

Thanks for digging out your 3868892. I just want to clarify what you mean by the 0.44" difference.

I would expect the 3868892 to place the belt groove of the pulley farther forward (farther from the pump resevoir) than the 377509. The reason is that if the 3868892 is intended to line up with the 3827843 add-on pulley that seats properly in the 3858533 crank pulley, the centerline of the belt groove would have to move forward by the difference in thickness between the standard-groove 3850838 dual crank pulley and the 3858533 deep-groove dual crank pulley. I believe that difference is approximately .330 inches.