# Newbie here with a pontiac 400 question



## Tafc18 (Jan 8, 2016)

I just finished building a mild 400 to go in a 1970 Lemans pro touring project. My question is can you run the heater hose into a water port on the intake instead of the cylinder head? I am using all steel braided line and there is not much clearance between the vac advance and the heater hose. Will make timing adjustment difficult. Thanks in advance


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## komodo (Oct 17, 2011)

That's a good question, I'm running mine (heater hose) from the back of the passenger side head (1970 400 #12 heads and intake).


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## Tafc18 (Jan 8, 2016)

I want to run my return from the heater core into the water port in the intake. Seems like a good way to run it, however I see that no one else is doing it. Why??


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## frenchGOAT (Jan 21, 2016)

Tafc18 said:


> I just finished building a mild 400 to go in a 1970 Lemans pro touring project. My question is can you run the heater hose into a water port on the intake instead of the cylinder head? I am using all steel braided line and there is not much clearance between the vac advance and the heater hose. Will make timing adjustment difficult. Thanks in advance


A bit off topic but I am curious, what does your mild 400 build look like ? What kind of work, cams intake etc.


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## BierManVA (Jan 6, 2014)

Tafc18 said:


> I want to run my return from the heater core into the water port in the intake. Seems like a good way to run it, however I see that no one else is doing it. Why??


I thought the return from the heater core was to the pump/timing cover and the supply was from the head?

I'd have concerns though that the flow entering where it wasn't designed to might cause cavitation and/or a restriction in normal coolant flow and could create hot spots in the engine.


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## 67Twistytee (Feb 24, 2014)

BierManVA said:


> I thought the return from the heater core was to the pump/timing cover and the supply was from the head?
> 
> I'd have concerns though that the flow entering where it wasn't designed to might cause cavitation and/or a restriction in normal coolant flow and could create hot spots in the engine.


Return is to the timing cover. The presumed "problem" with the design for the 400 is loss of a portion of coolant volume to the heater core that now cannot travel back through the head in the same way the drivers side does. This causes the passenger head to run hotter than the drivers side. It can be reduced some by using a restrictor in the short heater core hose from the rear head to the core. If you're not concerned about originality, some have also run and additional bypass hose from the rear head back to the crossover to reduce total flow to the heater core. 

Cavitation issues typically occur in the pump itself if you have a small or shallow stamped impellar. 

To TFAC18s question, the older 64 routing did take the heater core input from the crossover near the radiator inlet and outlet back to the timing cover. I suppose you could plug the rear cylinder head and try the routing you suggest. I see no reason why it shouldn't work.


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## Pinion head (Jan 3, 2015)

Some 301's used a 90 degree fitting that was drove into the same round hole at the back of the head, same hole that the "nipple" type fitting was driven into.

If I was modifying the coolant route in a race application, it would utilize a Y type routing to the rear of both cylinder heads, no pipe plug on the drivers side head.


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## BearGFR (Aug 25, 2008)

Pinion head said:


> Some 301's used a 90 degree fitting that was drove into the same round hole at the back of the head, same hole that the "nipple" type fitting was driven into.
> 
> If I was modifying the coolant route in a race application, it would utilize a Y type routing to the rear of both cylinder heads, no pipe plug on the drivers side head.


Which is exactly what I did on my car. I've got two nipples (chortle) on the car, one at the rear of each cylinder head, Y'ed together.

Bear


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