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vlad01 wrote:Thats the bypass loop that allows the thermostat to "sense" the engine temp, without it the coolant doesn't flow over the stat when its closed and causes the engine to overheat.

Okay, so provided I have a feed from that point to the back of the thermostat, all should be good yes?

yes but not sure how coolant flow goes reversing the manifold. you probably need vn series 1 head gaskets as their water jacket holes were biased towards a diagonal flow distribution from pump to rear of the head where later engines were a loop from pump to rear, up through the rear of the head and back to the front with some small % of flow taking a shortcut fin the front and mid section from block to head.

You also need to add some bleed points at the rear of the manifold (now front) to let air out where the water ports in the head are like vn s1 do.

You are better off buying a vn s1 manifold and reversing that and then that will work like a standard vp/vr cooling system setup with standard head gaskets.

Commwreck have some NOS ones for 100 bucks.

vlad01 wrote:yes but not sure how coolant flow goes reversing the manifold. you probably need vn series 1 head gaskets as their water jacket holes were biased towards a diagonal flow distribution from pump to rear of the head where later engines were a loop from pump to rear, up through the rear of the head and back to the front with some small % of flow taking a shortcut fin the front and mid section from block to head.

You also need to add some bleed points at the rear of the manifold (now front) to let air out where the water ports in the head are like vn s1 do.

You are better off buying a vn s1 manifold and reversing that and then that will work like a standard vp/vr cooling system setup with standard head gaskets.

Commwreck have some NOS ones for 100 bucks.

Just wait and see.

I agree with Vlad, a series 1 manifold may suit you better because of how the coolant flows through the manifold.

Also for a FI engine the bonus is blocked off PCV and cheap NOS manifold gaskets. Holmart had a ton of NOS ones for $11 a pair.

note the description is incorrect, they are indeed vn s1 only. I bought some once hoping just the pic was the wrong one but nope lol


http://holmart.com.au/online/prod935.htm

Yeah, definitely s1 only as they don't have the PCV hole.

immortality wrote:I agree with Vlad, a series 1 manifold may suit you better because of how the coolant flows through the manifold.

I respect your assessment, vlad's as well. And i appreciate you guys weighing in. I don't think you are wrong about the s1 manifold, but I'll just say that coolant only flows through the manifold because the thermostat is there and it's easier to include the coolant galleries in the manifold because of that. Coolant will flow from the bottom end into the heads and the manifold is the way out. From factory, there is no flow at the back of the passenger side head and only when the heater is on does it flow from the back of the driver's side.

immortality wrote:Yeah, definitely s1 only as they don't have the PCV hole.

Okay, so the pcv on mine has been blocked off for many moons. In the last lot of manifold mods the crank case breather ( not sure if that is the right term, but the little crank case pipe that feeds to the throttle body) has new blocked off also at the manifold flange. I have converted that to a coolant gallery with a -10 fitting where the pipe used to go to the throttle body. I will facilitate crank case ventilation via the rocker covers.

Yep, you are correct in that respect.

That little hose that goes from below the thermostat directly back to the water pump allows coolant to circulate around the engine (and past the thermostat) during the warm up cycle when the thermostat is closed. If you remove that hose no coolant will flow through that circuit and the thermostat won't open up. The series 1 manifold has a passage underneath that allows coolant to flow when the thermostat is closed to the front of the engine into that bypass hose as well as into the heater circuit, the later intake manifold does not have this link so if you remove that little hose it could be problematic.