My new intake has rear water crossover on it. Should I hook it up? Where should it be plumbed into? Water pump? What is the purpose of it? Thanks

If you are referring to the two 3/8 NPT fittings in the back of the manifold it is to get the hot water out of the back of the engine. You plumb it into the water outlet using a late model outlet that has two threaded fittings (they were there originally for a temperature controlled vacuum valve and a sending unit for the ECU to monitor engine temp originally). Stock manifolds connect the two banks of the engine together to equalize water pressure. By routing it directly to the outlet you keep that already heated water from having to migrate through the head to get out. This allows cooler water from the block to replace what is being sucked out of the heads by the water pump.

If you like boring holes and tapping threads you can tap into the high pressure side of the water pump and route two lines to the center of the heads between the two Siamesed exhaust ports to flood that hot spot with cool water. That really helps control detonation in half of the motor.

Big Dave

i have the same ports on my engine and was going to hook them up... bought all the fittings etc and by the time it was done i didn't have clearance for them. plus they interferred with the carb linkage... possibly the issue was my installation but i did everything i could to make it work and look nice.

it's all now on a shelf in my shop and not on my engine :(

that was a waste of $100.00+ :(

Its on a bbc. Could the rear lines be plumbed into the heater core hoses?
Thanks for the info

Dont feel bad Shifty, i got a few neat things to look at that i shouldn't have got. lol:D

You want to connect these ports to an area of lower pressure, preferably near the inlet of the radiator. Connecting them together really does nothing for the flow.

Can you use them for a electric fan switch screwed in there Thanks

yeah you probably could providing the switch is a 3/8 npt size.

that's the port size on the intake i believe.