Thread: 1969 chevy small block water pump hub bolt pattern

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I purchased a new water pump,long style but when I went to mount the pulley,the bolt holes did not line up, they are about a half a hole off. The water pump hub is half a hole smaller than the pulley. This pulley came off a 1978 camaro with a 350. Are there different water pump hub bolt paterns or do I need to get a different pulley?

SBCWP.jpg
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Some SBC pumps came drilled & tapped for two different 4 bolt patterns. This picture was highlighting shim sets sold by Mr Gasket, but clearly shows the difference in spacing. I'd say you'll either need to get a different pump or a different pulley to fit the new pump you have.