Guys with a Big Block & Factory Air - Question for you...stumped.

[Ozona]

I'm moving along pretty good with my big block transplant into my '72 GMC.

Currently working on getting all the accessories on to the front of the motor. No excitement with the alternator or power steering.

I am confused on the air conditioning though.

I have a 1972 original/factory cast iron mount that I bought from a board member here. It's in perfect condition, not bent, twisted, or really even scratched much.

However...I can't seem to figure out how to get it to mount up.

Take a look at these pictures:




The bolt locations on the front are obvious / work. Same with the accessory mount on the head that is in front of the exhaust port. However I the hole in the bracket and the hole drilled in the head for the exhaust bolt don't line up.

What do I have bassackwards?

Suggestions? Other than toss the stock style compressor? I'm trying to keep a pretty stock appearance.

Thanks!!!

[Jtrux]

If i'm not mistaken they are not designed to work with headers, modifications will be necessary. If you had manifolds, they'd mount right up.

edit: yeah, you need to machine a spacer or stack some washers to get it to work, more than likely you'll have to have someone make a spacer for it cuz it doesn't look like washers would work.

[Ozona]

I tried the stack of washers thing, that will work for a spacer. I also got a small steel spacer that will work from ace hardware.

I also have a stock stud, the issue is that the bolt hole in the bracket, and the bolt hole in the cylinder head don't match up. If you look closely in the picture you can see what I'm talking about.

So..problem is bracket bolt hole to cylinder head exhaust mounting hole misalignment or I'm doing something wrong. Or...the exhaust manifold doesn't use that bolt hole to the cylinder head and the stock stud I have screws into a bung on the exhaust manifold rather than the cylinder head.

[Ilike 72"s]

Do you have any more pictures. I'ts been years ago that I switched from a small to big block.I kind of remember it was confusing at the time because there many differant bracket parts. I had big and small block brackets all over the shop. Maybe tomorrow i'll take pictures if it will help.

[Ozona]

If there's a specific picture that would help, I can take them.

If you click the lower one so it enlarges it should give a pretty good idea of what I'm talking about.

The bolt hole in the header is not a problem... It lines up with the head. The problem as far as I can tell is the bracket doesn't line up to that bolt hole. It's off by about the diameter of a bolt.

If not I'm happy to post a picture that's different.

[Ilike 72"s]

Took some pictures for ya. I measured on top of the bolthead, center to center, and got 3 1/4 between. See if thats what you get.

[Ozona]

Those pictures are perfect, thank you.

The cylinder heads that I have are these:

http://www.worldcastings.com/prods_p...3_techspcs.htm

It says the ports are in the stock location. My brackets are identical to yours in position and measurements and are OEM brackets.

The world products cylinder head exhaust flanges are apparently raised, which is what's causing my problem.

I guess I could cut off that end of the bracket and weld on a chunk of mild steel and redrill in the right spot. However I've never welded cast iron to mild steel so don't know if that's possible.

Moving from a 350 to this BBC crate engine has been a bunch of work.

Thanks again for the pictures.