LSV

Does anyone have a diagram showing how the belts and pulleys are supposed to be on a 1970 454 Air equipped Corvette?

I'm attempting to finally get my AC up and running and the previous owner did some strange things with the belts and pulleys and I'm trying now to get them straightened out.

Currently I have a 3 groove pulley on the water pump, and a 2 groove pulley on the crank. One belt is on the 2nd groove from the block on the WP and crank going to the PS pump (which has a double groove pulley on it). There is then a belt going from the PS pump to the alternator.

The 1st and 3rd groove on the WP pulley are empty as is the first groove on the crank pulley.

I've got the AC cmpressor mounted, it appears to line up with the 3rd groove on the WP pulley...but it might be forward about a half inch...and the belt that Napa says it calls for is WAY too long to work.

I'm assuming things are way off from what they are supposed to be...so I'm looking first to see how they are really supposed to be...then I'll look for what I can do to get my AC cooling.

Any help will be greatly appreciated...

Thanks....

iree75

Since I wanted to do a big block conversion on my 75 and keep the A/C plus P/S I did a bit of research on this. Lucky for me, a friend has a 74 454 vert with PS and A/C all intact. I believe that a 70 would be the same.

There is a belt that should go on the inner most w/p and crank pulley only. Since neither of these move to tension the belt, there is an idler that pushes in on this belt to tension it. (You may be missing this) I believe Chevy did this because the A/C is driven just off of the w/p (3rd pulley). I have pics of the 74 at home and will try to post them tonight, if no one beats me to it. The idler pulley and brackets can be had from most vendors. Doc Rebuild, Ecklers etc.

-Frank

Easy Mike

The 70 assembly instruction manual (AIM) will show diagrams of the correct belt routing, plus the OEM part numbers for the original pulleys and include any notes on the installation.

LSV

Thanks Frank...

I guess I've about figured it out by what you've said and other things I've read today. My only question is going to be whether this car originally came with an air pump or not? It's just a driver, so I'm not really interested in putting an air pump back on it if it came with one, which means I'll have to figure out how long of a belt to put between the WP and the AC and then add an idler so I can run the belt from just the crank to the WP.

I wonder if it'll pull the AC with just that belt on it for now...just so I can get my AC guy to finish up with the rest of the AC install?

My other choice is to run one belt in the first groove from the block around the crank, WP, and Alt, then run a second belt in the 2nd groove around the crank, WP and PS, then run a 3rd belt in the 3rd groove around the WP and AC...

LSV

That would be great if I had one... Do you know anyone that does have one I could look at for just a few seconds...

Or any where online where I could look up a view of the front of the engine....

Steve's74

My '74 LS-4 may or may not be similiar to your '70. I don't think they changed a lot over those years. Here is a photo of the belt routing minus the idler pulley, the A/C compressor and (this is important) the AIR pump. The most likely reason that your belts for the A/C compressor are too long is that you're missing the AIR pump. The same belt drives both assemblies.



The other belt missing in this picture is the one closest to the block in the very first (or last, depending how you want to count) pulley. That belt drives only the water pump, and is tensioned by an idler pulley, which is missing in the photo. Notice that the alternator is driven off the P/S pump. So..... the order from the rear most belt to the one closest to the radiator is as follows: water pump (tensioned by the idler pulley), power steering pump, alternator (from the power steering pump only), air conditioning compressor and AIR pump, which is routed from the crank, over the water pump, over the AIR pump to the compressor. Which is why the A/C belt that you keep bringing home is so long.

If you want to drive the A/C compressor without installing the AIR pump, you'll need to keep trying shorter belts until you hit the magic one. Or, someone on here who has already figured out the right belt might supply you with the right number. I haven't made it that far yet....

Hope this helps.

Steve

454_71Stingray

the C3 catalogue from Corvette Central has a pretty good description. I didnt know how mine went on either when I started but one of the belts goes from the Crank to the WP to the AC, that one is pretty long. If I remember correctly I got the Idler from Dr Rebuild.

LSV

So those of you saying the AC belt goes over both the WP and the Crank...how many grooves are on the pulley on your crank?

Mine..and every one I've seen only has two grooves on the crank pulley and the AC seems to line up with the 3rd groove from the block...

Steve's74

If you look really close at the crank pulley in my photo, you will see three grooves. And my setup is completely stock, with the exception of the missing AIR pump (boxed up at the moment) and the missing idler pulley (which is on order). The belt setup on A/C and power steering equipped cars utilized three groove pulleys. One for the water pump, one for the P/S, and the outer one to turn the A/C. The power required to turn the compressor on a hot day required that the belt be driven from the crankshaft.

Steve

454_71Stingray

BTW your P/S pump should have two grooves too. I dont know if this was on all BBs or not back then but I have an Orignal A/C car an it is there. Also an offset Alt pulley that lines up with the outer P/S pump pulley groove. This was the worst part about rebuilding my engine, getting all the stuff to line up correctly.

LSV

Yes it does have all of that.

I have found that I was missing two parts...the idler assembly that tightens the first belt from the block that runs on the crank and WP alone and an air pump.

I'm currently looking for a deal on the idler asembly...but in the mean time, I was able to fit a belt from the WP to the AC and I'm in the process of getting all new hoses and seals put on the AC unit.

I did notice something else though... All of the wires going to what looks like the blower fan relay are disconnected...

Does anyone know which color of wire belongs on which post? Or is there a wiring schematic somewhere that I can refer to?

There are four wires in the loom:

Big Green wire (goes to the Compressor)
Big Purple wire (unconnected)
Small Blue Wire (unconnected)
Small Black wire (unconnected)

The relay has 3 spade terminals next to each other on one end and one spade terminal all by itself on the other end.

Thanks

iree75

Here are some pics of a 74.. minus the air pump... and then my solution sitting on a test stand..
[IMG]ftp://ftp.chodacki.org/427/454belts1.JPG[/IMG]
[IMG]ftp://ftp.chodacki.org/427/454belts2.JPG[/IMG]
[IMG]ftp://ftp.chodacki.org/427/454belts3.JPG[/IMG]
[IMG]ftp://ftp.chodacki.org/427/454belts4.JPG[/IMG]
[IMG]ftp://ftp.chodacki.org/427/454belts5.JPG[/IMG]
[IMG]ftp://ftp.chodacki.org/427/427marchpulley.JPG[/IMG]

iree75

Guess it doesn't work with ftp..

LSV

NICE!!!!

BTW, your old setup is exactly how mine is minus the idler pulley and first belt.