restricting airflow through radiatior to keep temp a normal

[EricZKC]

my 89 festiva runs cool, when it is about 35 degreese out, at idle it will warm up to operating tempature, but once i get moving, the temp drops and so does my heat in the car. I remember reading a post about blocking the airflow through the radaitor with cardboard and also blocking the huge hole since it has a small radiator.

My question is, how much of the radiatior do you block off? I don't want to overheat, i just want heat when i drive at 65 to 70. Any suggestions would help!
Thanks.

[qaking]

Eric,

Last winter I used a piece of waxed cardboard in front of my radiator that covered the lower two thirds and it seemed to work pretty good. Of course we don't have severe winters in Virginia Beach

[gdawgs]

Once it gets cold, I cover the entire radiator plus the hole to the left of it(where I assume the A/C condenser goes, not sure since I've never seen one with A/C). I use the cardboard from a 24 can case of pop(the kind Coke uses, not the Pepsi cubes). This helps keep the engine at proper operating temps and helps keep the cabin warmer. If the temp gets a little warm and the engine temp gets to the point where the fan starts kicking in, you just slide the cardboard that's covering the radiator over to the left a bit, to uncover a few inches of the radiator.

The engine should be able to stay at normal operating temps when it's 35° out, that's not very cold. Probably time to change your thermostat.

[EricZKC]

changed it when i flushed and filled the radiator last January. I think i drive too fast, and it just cools down too quickly. Thanks for all the input.

[gdawgs]

The first thermostat I changed on my Festiva, I used a cheapie from the auto parts store, and it never got up to normal temps(going by the gauge and what I was used to seeing on the gauge). They don't seem to seal properly. So I went to the Ford dealer and bought a factory one(and paid 4X more). But they work much better.