Street Rat

We just put a Vortec crate motor in a '78. The instructions say that we need to install a bypass from the intake to the water pump. There are not enough ports to feed the heater core if I do this. I read online that you should put a tee in the return line in this instance. I don't know if the return line is the 5/8" or 3/4" hose. Much thanks in advance.

toobroketoretire

The 5/8" pressure hose comes from the right side of the intake manifold and the larger 3/4" return hose goes to the right side of the water pump.

Ben65

Hey Majoho, I am experiencing the same issue with my 350 330ho. I've researched like crazy and nothing so far. You'd think that GM Performance would have an answer but nope. What did you end up doing and how is it working out for you?

AzMotorhead

Easy way to remember is water pumps suck.
Any hose that attaches to the pump is the suction hose.
Though the exception to this is the late model LS motors.
On any system other than fuel the return hose will be of a larger diameter than the supply hose. This holds true for PS hoses and water hoses

PRNDL

I learned something new today. Logic tells me that a water "pump" pumps water and I thought the water comes out of the hose attached to the water pump. (WRONG!). Logic also tells me that a supply hose being under higher pressure would be larger than the return hose. (WRONG AGAIN!) So much for "logic"

Fortunately, I don't think this misperception has caused me to screw anything up.....