71 SB A/C brackets don't align!

[Rick Church]

I have a real mystery problem with my car. Several Corvette guys, mechanics, and I have looked at my car and just can't figure this one out. It is a 71 small block with factory air. I have mentioned this in a previous post on the CorvetteForum.Com (http://forums.corvetteforum.com/zerothread?id=545391). From what I can see in the factory assembly manual and from looking at pictures in vendor catalogs, the A/C brackets look correct in size, shape, and appearance. Issue: The bracket that mounts to the exhaust manifold is supposed to align with bracket that mounts to the water pump but they don't. Where they come together, the compressor bracket is supposed to align with them both and serves as the forward mounting point (and hinge) for compressor mounting and adjustment. A bolt goes through the three to form the hinge point and mount and, additionally, this bolt head secures the small steel brace that secures the heater hoses and keeps them away from the A/C compressor. I hope I haven't confused you.

The problem is, there is about a half inch difference in alignment between the exhaust manifold and water pump brackets. It is impossible to get them to align as there are no adjustments and the parts can only be installed one way. The brackets have been installed with the correct hardware in accordance with the factory assembley manual. Since the bolts in the brackets attach to bolts holes in the block, I can't see where there can be an alignment problem there. The only thing I can seem to come up with is the possibility that one of the brackets may be a replacement part that is wrong. The exhaust manifold is a correct matching number part and the water pump is a Stewart Stage 1 pump.

Have any of you ever had this problem or heard of it. If so, what resolved the issue? I wish I had absolutely correct brackets to compare mine too. Do any of you have them laying around that I could make reference to? I will pay for shipping to and from your residence if I can borrow them for the comparison check.

Mystified in Tennessee (Rick)

[Rick Church]

Re: 71 SB A/C brackets don't align!

I got this reply, does it seem like a possible fix? Rick Church

"Rick,
I did this few days ago on my 72. Here's what you do to correct the problem:
Loosen all the bolts on the exhaust manifold and 2 bracket bolts on the water pump. Re-alignment the brackets. You need to move the exhaust manifold around.
Put a big bolt (3/8, I think) through the mating hole on both brackets to keep them aligned. Now, tighten all the bolts you can get to except the manifold bracket bolts. Remove the manifold bracket then tighten the 2 front bolts.
Install the bracket, align, then tighten the the remaining nuts and bolts."

[Joe L.]

Re: 71 SB A/C brackets don't align!

Rick-----

This alignment procedure would be a good procedure to follow. In fact, in its essence, it's the way that I usually align any system which involves multiple fastners and components. However, I'm not sure that this is going to solve the problem in your case.

Second, I don't think that you really need to compare your brackets with others. The configuration of the brackets is well-shown in the AIM. If yours are configured like those shown, then I'd say that it's a safe bet that you have the correct brackets. I don't think that there are any others which are subtley different but incorrect. If these are used brackets, then they must have worked at some point, so the question is why don't they work now? If they are new and/or reproduction, then it's possible that they were machined incorrectly, although I consider it unlikely.

However, you mentioned something about a Stewart water pump. That piqued my interest. The first thing that I would do is to check the thickness of the boss on the water pump leg that the front A/C bracket mounts to and compare it to the thickness of the same boss on a stock GM pump. In other words, measure the thickness of the boss from the block mounting surface to the machined front surface where the bolt normally seats. Many aftermarket pumps have different machining with respect to the mounting bosses on the pump legs. If so, you will have to have the boss machined down (or, shimmed if it's too thin which I doubt will be the case here).

[Patrick H.]

Re: 71 SB A/C brackets don't align!

Joe,

those were my thoughts, too. I'd look at the water pump, the only nonstandard item, as the cause of the alignment problems. I think you run into too much of the "one size fits all" mentality with the pump's size.

Patrick

[Rick Church]

Re: 71 SB A/C brackets don't align!

Joe, I thought about the water pump holes and spacing. The water pump bracket is spaced properly fore and aft. The way it appears now is that the hole in the bracket that mounts to the exhaust manifold is about 1/3 inch to high to align with the other holes. I put an old manifold bolt in an extra manifold I have to check clearance. I just don't see how there is enough play in all the components to cause this misalignment problem but I am desperate to figure it out. My brackets appear to be original and not replacemtns. The water pump had been replaced before so I don't have an "original pump" to make comparisons. The problem was there on the previous pump installation also. I dread loosening up the water pump bolts and causing leaks. Do you folks have any other recommendations? Rick

[Joe L.]

Re: 71 SB A/C brackets don't align!

Rick-----

You can measure the water pump leg boss thickness without loosening up the pump. Just put a machinest's rule against the block and measure out to the machined surface for the bolt. The measurement should be right at 2".