I just picked up a new waterpump for my 71 402 and it only has one heaterhose outlet on it. my old one had 2, one to the heater hose the other to the manifold. I have seen pictures of the very front of the manifold plugged before but I thought Id get some input before I plugged mine.

Thanks in advance.

Steve

The one front of the manifold is for the bypass hose. Bypass hose is a safety for a stuck t-stat. Dont know it helps or hurts, i have run with and without on differnt manifolds

Bob Adamsky

It is necesary to run a bypass if the car has a/c or has the heater loop removed.
On a/c cars the heater loop is blocked by a valve when the a/c is turned on, so there is no flow, same if heater loop removed, no flow.
The heater loop acts as a bypass.

I don't have a/c, and do have a heater loop. So I have removed my bypass hose and plugged the holes.
My T-stat also has 3 holes drilled in it, so that along with the heater loop gives me all the bypass I need until the t-stat is wide open or if it fails shut.

I have noticed that with no bypass, more coolant is forced through the rad., which in my case helped my engine run cooler.