Anyone out there with a 66 350HP and correct pulleys?

[Donald H.]

I have a 66 350HP that I have trying to get set up correctly with pulleys and belts. I've done a lot of research on this forum and actually have two threads that I started where I got info from others. My car is no A/C and No Power Steering.

I started out with all the wrong pulleys and now have what I believe to be correct based on my research:

Crank Pulley - #3858533. I bought this from GM as it is still available. Got the part number from research on this forum

Water Pump Pulley - #3770245. Got off Ebay and is correct per my research.

Alternator Pulley - #3871242. I have not been able to fine one of these, but I got correct dimensions from two sources and found one in Carlisle that matched the dimensions, e.g. diameter, overall depth, depth from alternator fan to V-Groove, etc. So what I have is withing 1/32" of the original.

Now my probelm - the double groove water pump pulley and double grooved crank pulley line up. Again from research on this forum, the alternator belt is supposed to go on the front grooves, and a captive belt on the rear. However, my alternator belt is a good 1/2" back of the front grooves of the Water Pump and Crank pulleys. I have some pictures attached, but it is difficult to see the issue.

If I move the alternator belt to the rear grooves, it will be better, but still will not line up. Is there anyone out there with a 66 L79 no A/C and no Pwr Steering with a correct pulley setup that I can talk to?

Thanks,

Don

[Scott S.]

Re: Anyone out there with a 66 350HP and correct pulleys?

I have a 66 350HP that I have trying to get set up correctly with pulleys and belts. I've done a lot of research on this forum and actually have two threads that I started where I got info from others. My car is no A/C and No Power Steering.

I started out with all the wrong pulleys and now have what I believe to be correct based on my research:

Crank Pulley - #3858533. I bought this from GM as it is still available. Got the part number from research on this forum

Water Pump Pulley - #3770245. Got off Ebay and is correct per my research.

Alternator Pulley - #3871242. I have not been able to fine one of these, but I got correct dimensions from two sources and found one in Carlisle that matched the dimensions, e.g. diameter, overall depth, depth from alternator fan to V-Groove, etc. So what I have is withing 1/32" of the original.

Now my probelm - the double groove water pump pulley and double grooved crank pulley line up. Again from research on this forum, the alternator belt is supposed to go on the front grooves, and a captive belt on the rear. However, my alternator belt is a good 1/2" back of the front grooves of the Water Pump and Crank pulleys. I have some pictures attached, but it is difficult to see the issue.

If I move the alternator belt to the rear grooves, it will be better, but still will not line up. Is there anyone out there with a 66 L79 no A/C and no Pwr Steering with a correct pulley setup that I can talk to?

Thanks,

Don

Don,

According to the 1966 AIM, the GM 3871242 alternator pulley is for big block with power steering (see UPC L72-A4).

According to Mark Gorney's recent pulley chart (2011), you have the correct crankshaft and water pump pulleys, but the alternator pulley should be GM 3829387. It looks like there are about six of them on the bay right now, from original to NOS to reproduction.

[Donald H.]

Re: Anyone out there with a 66 350HP and correct pulleys?

The number you suggested is also called out in the TIM & JG. I didn't have this book when I started the quest for correct pulleys. I found 5 or 6 instances in the forum where the #3871242 was called out as the correct pulley for my 350 hp.

There was also a disagreement as to where the captive belt goes. From what I could find in a search, there were pictures of the captive belt on the rear most grooves. If that is the case, then the 3829387 pulley would not work. I've seen picture of it and there is just not enough offset to place the alternator groove so that the belt aligns with the outside grooves on the waterpump and crank pulley.

So, if the #3829387 is correct, and since the TIM & JG says that is the correct part number, then the captive belt must be in the outside groove and the alternator belt on the inside.

I guess I'll now buy a 3829387 pulley.

Surely there is someone out there with a 66 L79 with original configuration that can confirm what is correct

Thanks,
Don

[Gary B.]

Re: Anyone out there with a 66 350HP and correct pulleys?

Don,

On my '66 L79 w/ no options the captive belt was in the groove closest to the radiator.

Gary

[Tony S.]

Re: Anyone out there with a 66 350HP and correct pulleys?

Mark Gorney has already done the research on your pulley set up. He published his research findings in an issue of the Restorer a year or two ago. It'll give you the correct answers for all of your pulley questions for your car.

Good luck

[Donald H.]

Re: Anyone out there with a 66 350HP and correct pulleys?

Mark Gorney has already done the research on your pulley set up. He published his research findings in an issue of the Restorer a year or two ago. It'll give you the correct answers for all of your pulley questions for your car.

Good luck

Yes I know about Gorney's article. However I don't have it. It came out about the time I joined the NCRS and it must have been in an earlier edition. I bought the disk but there is a gap in the Restorer editions of the disk and when I started to get actual copies. I think it must have been in an edition in between. I had asked on an earlier thread if someone could provide a copy of his article, but got no response.

[Donald H.]

Re: Anyone out there with a 66 350HP and correct pulleys?

Don,

On my '66 L79 w/ no options the captive belt was in the groove closest to the radiator.

Gary

Do you per chance know what pulley you have on your alternator?

Thanks,

Don

[John O.]

Re: Anyone out there with a 66 350HP and correct pulleys?

Yes I know about Gorney's article. However I don't have it. It came out about the time I joined the NCRS and it must have been in an earlier edition. I bought the disk but there is a gap in the Restorer editions of the disk and when I started to get actual copies. I think it must have been in an edition in between. I had asked on an earlier thread if someone could provide a copy of his article, but got no response.

The article is in Volume 35, Number 4 Spring 2009 issue of the Restorer. I have this issue and will send it to you. Hope it helps.

John

[Vinnie P.]

Re: Anyone out there with a 66 350HP and correct pulleys?

I apologize for not seeing this thread earlier...here's the article...

https://www.ncrs.org/restorer/1966%20small%20block%20pulleys.pdf

[Joe L.]

Re: Anyone out there with a 66 350HP and correct pulleys?

The number you suggested is also called out in the TIM & JG. I didn't have this book when I started the quest for correct pulleys. I found 5 or 6 instances in the forum where the #3871242 was called out as the correct pulley for my 350 hp.

There was also a disagreement as to where the captive belt goes. From what I could find in a search, there were pictures of the captive belt on the rear most grooves. If that is the case, then the 3829387 pulley would not work. I've seen picture of it and there is just not enough offset to place the alternator groove so that the belt aligns with the outside grooves on the waterpump and crank pulley.

So, if the #3829387 is correct, and since the TIM & JG says that is the correct part number, then the captive belt must be in the outside groove and the alternator belt on the inside.

I guess I'll now buy a 3829387 pulley.

Surely there is someone out there with a 66 L79 with original configuration that can confirm what is correct

Thanks,
Don

Don-------


If you obtain and install the 3829387 alternator pulley, all of your pulley alignment problems should be over. If they're not, then you have some other problem besides pullies because you will definitely have the correct pulley set for your application.

The most common "other problem" is the incorrect positioning of the waterpump hub on the shaft. There were 2 different hub locations used on these pumps and they differ by 1/8".

[Gary B.]

Re: Anyone out there with a 66 350HP and correct pulleys?

Do you per chance know what pulley you have on your alternator?

Thanks,

Don

Don,

I don't. The alternator that was on my car when I bought it was not original and I sold it some years ago. I bought a restored and correctly dated alternator from John Pirkle and that came with whatever pulley he believed was correct for my L79.

Gary

[Donald H.]

Re: Anyone out there with a 66 350HP and correct pulleys?

I apologize for not seeing this thread earlier...here's the article...

https://www.ncrs.org/restorer/1966%2...%20pulleys.pdf

Thanks, I think the first Restorer I got after I joined was Fall 2009 so I missed that article

[Scott S.]

Re: Anyone out there with a 66 350HP and correct pulleys?

The most common "other problem" is the incorrect positioning of the waterpump hub on the shaft. There were 2 different hub locations used on these pumps and they differ by 1/8".

Joe,

What is the procedure to determine whether the water pump hub is in the correct location? And if it's not in the correct location, how do you "fix" it?

[Joe L.]

Re: Anyone out there with a 66 350HP and correct pulleys?

Joe,

What is the procedure to determine whether the water pump hub is in the correct location? And if it's not in the correct location, how do you "fix" it?

Scott------


Well, the best procedure is the empirical. In other words, determine how far the alignment is off and then adjust the hub to correct it. Since you know that you have the correct waterpump and crank pullies, when you obtain the correct alternator pulley, you'll know that you have the complete correct pulley set.

Then, you measure how much the waterpump pulley mis-aligns from the crank pulley. clem has posted a procedure for measuring the amount of mis-alignment.

If the waterpump pulley is too far REARWARD, then I would recommend the use of spacer(s) to shim the pulley forward. The spacers are placed on the waterpump hub before the pulley is installed. Spacers can be obtained from automotive speedshops such as Summit Racing under Moroso or Mr. Gasket brand names. It is much easier and safer to use spacers than to try to re-position the hub for this sort of mis-alignment condition.

If the waterpump pulley is too far FORWARD, then it needs to be pressed further back onto the shaft. Unfortunately, the proper way to do this requires removal of the pump from the engine. Then, with the pump's rear cover removed and the end of the shaft supported, press the hub further onto the shaft by the required amount.

Obvious question: can you just drive the hub further onto the shaft with the pump still installed on the engine? Yes, you can but you risk damaging the bearing doing it this way. But, you MIGHT get away with it.

[Rich G.]

Re: Anyone out there with a 66 350HP and correct pulleys?

Searched this thread because on my 66 L79 the captive belt is in front of the alternator belt and I wondered if that was backwards. The car is a driver and I have no idea which pulleys are where for what,or even if the alternator set up is correct but I have always wondered. Gary B's post above indicates his car is configured that way too. I know this thread references an article which I don't have and Vinnie P posted link to it, but the link is dead.

So the simple question is, is the captive belt closest to the radiator or not?

Rich G.