[Bob Carriere]

Hi Michael

You will need to check that casting number.....should be 7 digits..... the begining of 3836XXX is the proper sequence for a late 57-58 261 engine....

As for the pulley I may have one sitting in the barn... we never use them because we usually change the water pump.... we use a 216 water pump with an adapter plate. Your water pump looks like a typical in block 261 water pump BUT the pulley has been removed and replaced by a 216 pump pulley. Now on a water pump there is a machined adapter that is pressed on the pump shaft..... then the pulley bolts on by 4 1/4 bolts onto the adapter.

Note that the bolt pattern of the pulley you have is different from the original 261 larger pulley. You would have to obtain not just the original pulley but also the adapter backing....... you woudl no doubt need an hydraulic press and some serious ehat source (oxy-acet. torches) to remove the existing pulley..... unless you have a fully equipped garage, I would take the pump to a competent machine shop to do the change over.

I will post some pictures from home of the 261 set up..... or you can check Phil Waterman's excellent web site for tons of pics.

Meanwhile check those casting numbers.

Boob