I've got a Luego Viento with a Rover V8 in, a carb-fed 3.5 from an SD1. I didn't build this car.

I've currently got the engine out to swap the gearbox for a later and hopefully better R380 box, the current LT77 being a bit tired. Whilst it was out I thought I'd sort the heater out.

At the moment, the heater matrix in the car is permanently on - and on a warm day it would be good to turn it off! No problem thought I, I've got a spare latching switch on the dash, and CarBuilder do a normally closed 12v flow valve - it can only have the flow on or off, but that'll do for what I want.

The hose to the heater starts off next to the water pump, branching off the main hose to the radiator - it runs up to the heater matrix and back to the expansion tank - but - problem is it runs back via the intake manifold. The car has an Offenhauser dual port manifold, but I believe the standard Rover one was the same, coolant flows in at the back and out at the front so I presume it is doing something - it's not just there to neaten the plumbing?

If I fit this valve it'll stop the coolant flow through the manifold as well. The standard SD1 heater I'm guessing would have been the same, or did it have a bypass so even if cabin heating was off the coolant would flow back? Anyone got any ideas?

Thanks a lot!

I think I've answered my own question, courtesy of a post I've found on another forum. The flow is the other way, into the front of the inlet manifold - but - that is connected internally into an outlet down into the block, the outlet at the rear of the manifold was always for the heater and can be blocked by a flow valve no problem, as the flow down into the block is maintained.

I need to have the manifold off to replace the valley gasket anyway so I guess I'll see for sure then!

Car Builder Solution do 2 way controls so you can route the flow past the heater matrix or through it so flow will always go through the manifold which is probably why the original builder left the flow permanently on

Car Builder Solution do 2 way controls so you can route the flow past the heater matrix or through it so flow will always go through the manifold which is probably why the original builder left the flow permanently on

You might be better off with fitting a cable operated flap to restrict airflow through the heater matrix rather than using any tap to restrict water flow which may?? affect coolant flow/ cooling .

I've got there with this one with the help of someone who knows these engines well, and it's not completely straightforward.

There has to be a bypass past the thermostat to enable engine coolant flow when the thermostat is closed - the water pump pushing coolant up through the block and heads to eventually arrive at the inlet manifold, where it either flows off to the radiator or - if the thermostat is closed - has to return directly to the water pump until the engine has warmed up.

If the thermostat is closed some RV8's have a direct bypass past the thermostat for this, but some use the heater circuit instead. Mine has the thermostat bypass so all is good, I can safely stop the heater flow.