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Big Block

BB accessory bracket factoids

I verified last night that the 72 and up water pump housings (pass side inlet) have different locations and spacing for the accessory mounting AND thermostat location, which means you cannot use the later p/s pumps or a/c brackets on the earlier housings. I had thought that I could use the later a/c brackets on my 67-71 housing because the distance between mounting holes was the same, but when you actually try to install it, it interferes with the water outlet because the relationship between these two holes and the rest of the components is different. Here's a summary of what I have discovered so far:

- the three styles of big block w/p housings are:

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63 thru 66

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67 thru 72

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and 73 thru 78.

- 67 thru 71 p/s pump brackets (two piece half moon shape with Federal pump) will fit on all three styles of w/p housing, but then you are forced to use this exceedingly crappy design

- 72 and up p/s pump brackets (with Saginaw pumps) fit only on 72 and up w/p housings because of spacing and/or hose clearance

- a/c compressor brackets will work only with the corresponding year w/p housing

- alternator brackets seem to be more forgiving with regards to crossing vintages, but are still not completely interchangeable

- there are many instances of differences between B and RB engine accessory brackets even within the same model year because of the additional height of the RB deck. Basically, any bracket that uses a mounting hole in the cylinder head will be affected

The bottom line: always use a complete set of accessories, including the water pump housing, consistent with the engine year and type to avoid months or even years of frustration trying to get everything to work correctly.

I know that the triangle shaped alt bracket works on the two later housings as well as the MP housing. The early alternator brackets only work on the early housings. (which are getting hard to find these days)

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MP Housing


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