18 replies to this topic

[Icey]

I plumbed ours in, partly because it made plumbing neater, but also because it serves a purpose - it reduces the affect of wall wetting. If this provide more stable fueling then that's the win I'm interested. If it costs me 1-2bhp at the top end, not interested, it won't be noticed.

[Tornado99]

Most cars of the period had some type of pre heating on intake air and or manifold. Another reason for this, not yet mentioned, is for better emissions reductions. Engines have lowest emissions when at max thermal efficiency. The quicker you get to that point after cold startup the better overall emission levels become. I suspect if you review when the laws being introduced for car emissions came into effect, you'll see these systems appearing on cars.

Carb icing was previously mentioned. This can occur even with ambient air above freeze point. You are sucking fuel in liquid form into carb throat, where it aerosolizes and vapourizes rapidly. This change of state absorbs a lot of heat (think a/c cooling system). At certain humidity levels, icing will occur.

Edited by Tornado99, 06 February 2021 - 06:52 PM.

[Tds76]

I plumbed mine in primarily because it tidied up the hoses from the heater valve to the heater.
With respect to benefits or negatives of heat transfer as have been described - if you have the heater valve closed then there is no heating of the manifold so okay when driving on warm days. If the valve is open as it would be when the weather is cold then you get the benefit of heating the manifold.

Cheers, Paul.

[Icey]

I plumbed mine in primarily because it tidied up the hoses from the heater valve to the heater.
With respect to benefits or negatives of heat transfer as have been described - if you have the heater valve closed then there is no heating of the manifold so okay when driving on warm days. If the valve is open as it would be when the weather is cold then you get the benefit of heating the manifold.

Cheers, Paul.

I plumbed mine in with a Ford recirc valve so there is always water flowing as I wanted coolant flowing through that end of the head regardless. When you turn the heater on, the fan is powered and the valve is released (diverting flow through the matrix).