Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

[Joseph A.]

I know there have been many questions about the correct pulley configuration for the 1965 327/350 w/PS & AC options. This is a 1 year only pulley setup which uses the deep groove C/S and W/P pulley's and the issue is the C/S add on and P/S pulleys. When I purchased my car all pulleys were still intact. I have included pictures of the complete setup as installed on my restored engine. The correct pulley part numbers are as follows, C/S pulley 3766987 (replacement 3858533 will work), C/S add on pulley 3827843, W/P pulley 3848904, and the P/S pulley 3868892.

[Joe R.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

I know there have been many questions about the correct pulley configuration for the 1965 327/350 w/PS & AC options. This is a 1 year only pulley setup which uses the deep groove C/S and W/P pulley's and the issue is the C/S add on and P/S pulleys. When I purchased my car all pulleys were still intact. I have included pictures of the complete setup as installed on my restored engine. The correct pulley part numbers are as follows, C/S pulley 3766987 (replacement 3858533 will work), C/S add on pulley 3827843, W/P pulley 3848904, and the P/S pulley 3868892.

Hi Joseph:

This is interesting to me because I have a '67, and for '67 the entire pulley set was standard-groove. My question is whether it is possible that for '65, they used deep-groove pulleys on the crank, water pump, and alternator, but standard-groove pulleys for the crank add-on pulley and the PS pulley.

Could you take a look at the crank pulley stack-up (effectively a 3-groove setup) to see if the add-on pulley looks like a standard-groove?

If it doesn't, could you try to measure the diameter of the PS pulley? So far I can not find much info on either the add-on pulley or the PS pulley part numbers that you mention.

[Joseph A.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

You are correct 66 thru 68 used the standard groove pulleys, as I stated 65 is a 1 year only pulley configuration. The W/P and C/S pulleys are deep groove while the C/S add on and P/S pulley are standard groove. That is why if you look in the compressor mounting section of the AIM you will see 4 spacers at the mounting points of the compressor that will say "L79 only". This pushes the compressor out 1/4" to make up the difference in the W/P and C/S pulley widths since they are deep groove pulley's. Also in 65 the W/P with A/C pulley is a smaller diameter than the non A/C pulley. I think they did this to speedup the water pump so when the A/C was on the engine cooled better.

[King M.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

I don't know about the one year only part. I have a 67 l79 c60 car with deep groove pulleys on wp and cs. They came on the car. There are a few other 67 in this configuration that have posted here as well.

[Joseph A.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

Attached is the W/P pulley section of a July 1969 Parts catalog, first of all we are talking AC & PS, a 67 327 with AC only uses the same W/P pulley as the 1965 deep groove, but if you do have PS it uses pulley 3883234 as shown and I believe that is a standard groove pulley. And as you can see it does not affect 65 because that configuration is by itself. I have also included the P/S pulley section and as you can see the P/S pulley is 65 only.

Water Pump Pulley Section

WP Pulley.jpg

Power Steering Pulley Section

PS Pulley.jpg

[Mark E.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

This thread from 2008 throws a lot of PNs around, but concludes deep-groove pulleys were probably not used on '65 Corvettes with A/C and PS. Has the thinking about this changed?

https://www.forums.ncrs.org/showthre...kshaft-pulleys

[Joseph A.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

I had a 65 previously where the car was a basket case and I was trying to find out what pulleys went on what engines. After deciding to sell the car, I purchased this 65. This car was complete and all the pulleys were in place that is why I posted this thread because of all the trouble I went through when I was working on my first 65. I have a friend who was a parts manager in the sixties and he had a July of 69 parts catalog and when I took off the pulleys they were a match to his parts book. They were deep groove pulleys on the W/P & C/S and standard groove C/S add on and P/S pulleys. If you look in the N40 section of the 65 AIM it shows a page for 65 L79 only and the pulleys they use. for the P/S pump it is 3868892. That is why they developed the 3868892 pulley because the standard 509 pulley only works with standard groove W/P & C/S pulleys not deep groove pulleys.

[Joe R.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

This thread from 2008 throws a lot of PNs around, but concludes deep-groove pulleys were probably not used on '65 Corvettes with A/C and PS. Has the thinking about this changed?

https://www.forums.ncrs.org/showthre...kshaft-pulleys

The above thread from 2008 contains several postings from me, so I won't repeat the content here. For 1966-67, a Corvette L79 that had *both* A/C and PS used the standard-groove pulley set. I think this has been well established by various researchers. Regarding the reason why, my theory is that GM found that the deep-groove pulley set (with three grooves on the crankshaft) pushed the PS pulley too far forward, causing possible interference with the frame rail. I have test-fitted this combination and it looks too close for comfort when considering normal production tolerances.

However, there has been conjecture that the 1965 configuration might have been deep-groove. The problem is that the add-on crank pulley and the PS pulley are extremely rare. I have never found an example of either one.

I think Joseph Aronne has finally solved the mystery. For 1965, GM got a little extra room (about 1/8 inch) by using a standard-groove add-on crank pulley and a standard-groove PS pulley. All the other pulleys were deep-groove.

My guess is that GM found even this concession did not provide enough room to cover normal production tolerances, so in 1966 they threw in the towel and just used a full standard-groove pulley set. That moved the PS pulley back another 1/4 inch compared to the 1965 configuration.

[James W.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

Here are some pictures of my unrestored '65 with L79, A/C, and P/S. Sorry I don't have better pictures of the power steering pulley. Yes, the belts in a few of the pictures do not line up due to a water pump rebuild and not getting the hub correctly relocated in the shaft. That has since been corrected.


Regards,

James West

[Joe R.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

Here are some pictures of my unrestored '65 with L79, A/C, and P/S. Sorry I don't have better pictures of the power steering pulley. Yes, the belts in a few of the pictures do not line up due to a water pump rebuild and not getting the hub correctly relocated in the shaft. That has since been corrected.


Regards,

James West

Hi James:

Thanks for posting this. I thought I understood (finally) the 1965 setup, but the crankshaft pulleys in photo #3 do not look like what I expected to see. I expected all three grooves to be stacked back-to-back, but the groove on your add-on crank pulley for the PS pump appears to be sitting somewhat forward of the of the main crank pulley.

I'm wondering whether it is possible that the crank add-on puley is correct, but the crank's dual pulley is actually a standard-groove rather than a deep-groove. That would accout for an approximate 1/4" gap between the dual pulley and the add-on pulley. It would also aggravate the alignment issue between the water pump pulley and the crank pulley.

[Mark E.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

More general, but related, dumb questions here:

How does a deep-groove pulley differ from a standard-groove pulley? Deeper, or wider, or both? By how much?

How many different pulley groove sizes are there? Only two (deep and standard)? Or are there also different widths to accommodate different belt widths?

[Joe R.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

More general, but related, dumb questions here:

How does a deep-groove pulley differ from a standard-groove pulley? Deeper, or wider, or both? By how much?

How many different pulley groove sizes are there? Only two (deep and standard)? Or are there also different widths to accommodate different belt widths?

Hi Mark:

Attached is a photo that shows a double deep groove pulley next to a double standard-groove pulley. Since the angle of a V-belt is fixed, making the "V" deeper also makes it wider. Deep-grooves are nominally 1/8 inch wider that the top than standard-grooves.

The problem grows as you stack more grooves. In a C2 with A/C and PS, the crank pulley has three grovves (made up of a double-groove pulley with an add-on single-groove pulley. For the outermost pulley that is used to drive the PS pump, the difference in the PS pulley centerlines between a standard-groove setup and a deep-groove setup is 3/8 inch.

You can see how things get messy if you try to mix standard-groove pulleys with deep-groove pulleys. Many of the pulley alignment problems I have seem are caused by mixing the two types.

Regarding you question about how many versions of each type there are, I have always assumed that GM used only one size of standard-groove and one size of deep-groove, but that is just an assumption. For all of the pulleys I have, the grooves seem to be just one width for each of the two types.

[Mark E.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

Thanks Joe! Very helpful.

I understand the same width belt is used in standard and deep groove pulleys. This places the top of the belt below the top of the deep groove pulley for more control at high RPM. Is this correct?

I haven't paid close attention, but I also believe the standard groove pulleys seem to be the same width. Maybe others can comment about this.

But if this is the case, why are different width belts specified? For example, I think all the pulleys on my '70 LS5 are standard groove (and the same width) yet two belt widths are specified (15/32" for WP and AC; 7/16" for alt and PS; ).

So this means the top of the 7/16" belts appear lower than the 15/32" belts (which looks a bit funny). Is this correct?

Is this because wider belts are specified for higher loads (in this case, the WP and AC have higher loads, so they use a wider belt than the alt or PS)?

[Leif A.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

FWIW...my '67 with C60 and PS.

[Mark E.]

Re: Correct 1965 327/350 W/AC & PS Pulley Configuration (includes pictures)

It looks like Leif's C/S has three standard grooves with no gaps between them. While James' C/S has two deep grooves behind a standard groove PS add-on pulley with a greater gap in between.

Correct?