Cold in my Factory Built

Since my RV 12 is factory built Vans tells me I can't modify the engine with a Thermostasis, I have applied foil tape to the oil cooler and that's helping with oil temp but my Cylinder Head Temps are consistently low and there's no cabin heat available. Can I put foil tape over the air inlets at the front of the cowl to try to warm things up, or carve a plug out of Ethafoam that would partically block those two round openings?

The simplest solution is to take a sheet of aluminum and cut to cover a portion of your radiator, bend the sides to make a lip to hug the sides of the radiator and cut and bend a couple of tabs to hold position at top. If done carefully it will slide down between the radiator and seal with the bottom cowling on and keep a tight seal. You can then insert or remove with only the top cowling off. I also add a piece of aluminum duct tape on top just in case to hold it in position so it could not move out of position. I cover about 40% of my radiator.

Duct tape works for the front but once you know how much blockage cut a piece of aluminum the correct blockage and drill holes to match the oil cooler bolt location. I slotted one so you only need to remove one and loosen the other to either add or remove. I also painted black to match my radiator. Covering about 40% gave me about 190 degrees oil temperature today at freezing temperatures.

If able ... get some aluminum tape (in a roll) and if u can reach back and cover maybe 1/3 or so of the radiator . If the OAT is below 35F, that will help keep the temps up. You need around 180-190 to get good cabin heat.

Check these two threads from the past that tackle this problem

Check these two threads on the subject
I use these when the high for the day is below 40 degrees.
Between seasons I use the oil cooler cover only and may put it on in the morning and after breakfast take it off for the return flight when things have warmed up a bit.

http://www.vansairforce.com/community/showthread.php?t=51667&highlight=oil+radiator+cover

http://www.vansairforce.com/community/showthread.php?t=106889&highlight=oil+radiator+cover