1968 Pulley and V-Belt Routing with A/C & PS

[Gary B.]

With the release of the new 68-69 TIMJG, a question has been raised about the routing of V-belts on engines with A/C & PS. A third pulley was added to the lower crankshaft pulley for this application. Was this pulley added for both 427 and 327 engines?

Can you please post pictures of the front of your engine if your car is equipped with Air-Conditioning and Power Steering. Looking for all engine options that used Air Conditioning.

We are trying to see what pulleys were used and how the belts were routed.

Thanks for your help.

Gary Bosselman

[Joe L.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

With the release of the new 68-69 TIMJG, a question has been raised about the routing of V-belts on engines with A/C & PS. A third pulley was added to the lower crankshaft pulley for this application. Was this pulley added for both 427 and 327 engines?

Can you please post pictures of the front of your engine if your car is equipped with Air-Conditioning and Power Steering. Looking for all engine options that used Air Conditioning.

We are trying to see what pulleys were used and how the belts were routed.

Thanks for your help.

Gary Bosselman

Gary------

I'm out-of-town right now and can't get to my references to confirm. However, I can say this much: No pulley was added to the balancer pulley for any 1968 427 application. All 427 applications used a single, 2 groove balancer pulley.

300 hp small blocks with power steering, including those with A/C, did use a single groove, add-on balancer pulley in addition to the 2 groove pulley. 350 hp small blocks with power steering and without A/C did not use an add-on pulley. I just don't recollect the configuration for 350 HP with power steering and A/C.

All 1968 applications also were equipped with AIR.

[Gary B.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Joe;
I have seen two pretty original 68 427s with the crankshaft add-on pulley. The last was the Regional Meet in Frisco, TX. a few weeks ago. It was a PS and A/C equipped car. Both cars I have seen, nothing was routed around the add-on lower pulley. First car the A/C was not hooked up and AIR was missing. The car in Frisco, the A/C was routed over the water pump pulley, AIR pulley and A/C pulley.

I don't have access to lots of 68 Air Condition cars around here. Hence my post.

Gary Bosselman

[Joe L.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Joe;
I have seen two pretty original 68 427s with the crankshaft add-on pulley. The last was the Regional Meet in Frisco, TX. a few weeks ago. It was a PS and A/C equipped car. Both cars I have seen, nothing was routed around the add-on lower pulley. First car the A/C was not hooked up and AIR was missing. The car in Frisco, the A/C was routed over the water pump pulley, AIR pulley and A/C pulley.

I don't have access to lots of 68 Air Condition cars around here. Hence my post.

Gary Bosselman

Gary------

I'm out-of-town right now and, thus, cannot check my references; I'll do so when I get home about Saturday. Here's what I can say now, though:

Most 65-69 big blocks used a 2 groove, cast iron balancer pulley. It is impossible to use any add-on pulley with this balancer pulley, absolutely impossible.

Beginning with 1968, a 2 groove, stamped steel balancer pulley was used with most 427 applications. Theoretically, an add-on pulley could be used with this pulley but I am not aware of any add-on pulley that will "nest" with this pulley. There may be one but I just can't think of it as I sit here. As far as I recall, I have NOS examples of every pulley ever used for any 1968-72 Corvette [none for sale] and I just don't recall an add-on pulley for the 2 groove, stamped steel big block balancer pulley. But, as I say, there may be one that I've just forgotten.

By the way, there was NO 1968 to 1974 Corvette application, small block, big block (or medium block if they ever made any), which used a pulley system in which there were any unused grooves.

[Gary B.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Thanks for the reply.
In working on the new 68-69 TIM&JG, I looked a lots of 68-69s. I saw none with cast pulleys. I have two 68 435hp cars on my premises right now, both have stamped steel pulleys. Very original, unrestored cars. The L88's I got photos of, for the new manual, had stamped steel pulleys. So...
When you get home, I would appreciate you looking at your references and see what it says. If the manual is incorrect, I would like to correct it.
Appreciate all your help.
Gary Bosselman

[Joe L.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Thanks for the reply.
In working on the new 68-69 TIM&JG, I looked a lots of 68-69s. I saw none with cast pulleys. I have two 68 435hp cars on my premises right now, both have stamped steel pulleys. Very original, unrestored cars. The L88's I got photos of, for the new manual, had stamped steel pulleys. So...
When you get home, I would appreciate you looking at your references and see what it says. If the manual is incorrect, I would like to correct it.
Appreciate all your help.
Gary Bosselman

Gary------


I'll check when I get home. After 1967, the stamped steel big block balancer pulley did come into pretty widespread use. However, I believe at least some 1968-71 big blocks continued to use the cast iron pulley.

One thing I do know: the cast iron pulley and the stamped steel pulley are completely functionally interchangeable. So, one can be easily swapped for the other without changing anything else.

[Joe L.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Thanks for the reply.
In working on the new 68-69 TIM&JG, I looked a lots of 68-69s. I saw none with cast pulleys. I have two 68 435hp cars on my premises right now, both have stamped steel pulleys. Very original, unrestored cars. The L88's I got photos of, for the new manual, had stamped steel pulleys. So...
When you get home, I would appreciate you looking at your references and see what it says. If the manual is incorrect, I would like to correct it.
Appreciate all your help.
Gary Bosselman

Gary------

I've now been able to research this issue further. I find that it's pretty much as I mentioned above.

For 1965-67 Corvette, cast iron, 2 groove balancer pulley GM #3863108 was used for all big block applications.

For 1968-69 L-36, 2 groove, stamped steel balancer pulley GM #3921923 regardless of whether or not equipped with N-40 and/or C-60.

For 1968-69 L-68, L-71, and L-88, it's less clear. However, I think that most were equipped with the 3921923 stamped steel pulley. However, late 1969 L-88 was supposed to be equipped with the 3863108 cast iron pulley. It's possible, though, that some 1969 L-68 and L-71 were also equipped with the 3863108. The 3863108 was also used for all 1971 LS-6, its last PRODUCTION use. As I previously mentioned, the 3863108 and 3921923 are functionally interchangeable. Due to this fact and due to what I believe was some "factory uncertainty" on balancer pulley use for big block applications, I would recommend that any 1968-69 big block seen with either pulley be deemed to be correct.

I have confirmed what I mentioned above regarding an add-on pulley for big blocks. I cannot find that any such pulley ever existed or was used for any big block application in PRODUCTION. In addition, I know of no add-on pulley that will properly articulate with the 3921923 balancer pulley. If you have some 1968-69 big blocks that have an add-on balancer pulley (i.e. forming a total of 3 belt grooves at the balancer), I would love to see photos of that. Even more important, I'd love to know what the part number is of this pulley. Most pulleys have part numbers stamped on them.

[Jeff W.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Gary, my base model '68 has AC and PS. Do you continue to seek a photo? If so, can you be more specific as to the angle and field of view you are seeking?

Jeff (St. Louis - No, my car didn't end up very far away from its birthplace)

[Gary B.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Yes please. I received some photo's of a 327-350HP with PS and AC. A base motor would help tremendously. Still looking for 427 pictures though.
The pictures of the lower pulley arrangement, the power steering pulley and the water pump pulley arrangement would be great. I would like to make sure what we describe as pulleys is correct.

Thank you, appreciate your help.
Gary B

[Jeff W.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Does this help

[Joe L.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Does this help

Jeff------


This could be either 300 HP or 350 HP with C-60 and N-40. However, the AIR drive pulley has been removed.

[Jeff W.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Sorry for the poor post. I did that from my phone - fat fingered the upload button, tried to delete the duplicate images, and the system wouldn't let me edit my message that was 'too short'. Ugh!

The car is a 300 HP with AC and Power Steering. December 1967 build. When I first replied about my car I forgot the prior owner took off the AIR pulley (I have it). He had replaced the water pump with an incorrect version and the belt was catching on the pulley, so he removed it. I plan to restore it after I rebuild the original water pump.

I'm sorry I cannot be of more help.

Jeff

[Gary B.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

Jeff, Thank you for the pictures. Really appreciate the help. A picture of the "extra" lower crankshaft pulley that drives the power steering, and the stamped steel power steering pulley is what I was looking for. Thank you, thank you.
Gary Bosselman

[Jeff W.]

Re: 1968 Pulley and V-Belt Routing with A/C & PS

My pleasure. 'Glad it was helpful. Let me know if there is something more I may do.

Jeff