Water pumps

[marfulle]

I am putting a 51 plymouth motor in my 48 2 door sedan. The new motor needed a water pump. I ordered a water pump for a 51 plymouth and when I got it, it looked just like the water pump from my 48. It looks like it has the external bypass the comes out from the top of the pump. Do I just block it off or is this the wrong pump? (I hope I am making sense).

[Plymouthy Adams]

Without a picture, I am only able to guess..but all you have to do is change the backing plate for the pump you want to run to the new assembly...is this what you are referring to?

[marfulle]

I understand that the pumps are pretty much the same. Do you have a pic of a backing plate for my 51. The new water pump that I have has the external bypass hole up top and the two bolt hole for it.

[martybose]

Most of the new waterpumps have both the bolt holes on top for the bypass fitting and the tapped center hole for the 90 degree bent fitting that is used for the heater return when there is no bypass fitting.

The only difference otherwise is an additional 1/2" hole in the backing plate that mates up with the later model block.

The 50 Dodge block that I used was set up for a internal bypass pump, and I can personally vouch for the problem of using an internal bypas pump AND the outside bypass fitting!

Marty

[marfulle]

I understand now about the top fitting and it being tapped for the heater line. How many holes should the backing plate have? I have the one for the distribution tube and then there is one in the middle. Should there be another one?