Hi Sam,

Thanks for the infos, obviously it helps to diagnose a problem if we get all the parameters... From what you told us :

1) I would seriously consider changing the oil to 20W50 full synthetic oil to keep internal temp as low as possible.
2) make sure your rad is large enough; see my blog post How to calculate glycol radiator for your engine on this website. I used that calculation and it turned out OK
3) how is your fuel system built from the fuel tanls to your engine ???
4) you mention the Aerovee carb, are you using the right needle ?
Mine came with 3-4 different needles - maybe the one installed is not sending enougn fuel to your engine...
5) air goes thru your rad to cool off the glycol, what about EXIT for the hot air ? Exit area should be 1.5 larger than the entry. Also, air should be forced out - pulled ´
6) what type of gearbox - reduction, propellor, engine speeds are you looking at ?
7) what blade angle ?

Photos of installation would also help...

Hi Sam,

Some more thouths:

1) my prop is a 3 blade 70inch Warpdrive (large paddle) set at 14.5 degrees. Angle is taken at 70% of the blade lenght - not at the tip. The tip is too small to make a good angle calculation...

2) my redrive is 2.32 to 1 ratio and my engine is turning 5200rpm at WOT which is 2250rpm at the prop. I used to run the engine at 5600rpm (lower blade angle) but wasn't getting all the speed I could at level flight. 

3) What is your reduciton (beltdrive) ? 2to1, 2.5to1, 2.3to1 ? If your prop turns too fast it is not helping your engine to cool off.

4) Did you do a PULL TEST ??? Mine showed between 420-450 pounds of thrust static which place the engine at the same HP level as a 912ULS. I'm asking this because if you overrev the engine you may not load it enough.

So,

1) check fuel delivery (mixture needle) at high speed may not deliver enough fuel to the engine causing overheating. Fuel quality (90octane+)

2) Glycol radiator installation : large enough rad, large enough EXIT area, glycol quality, NO THERMOSTAT and NO AIR in the system. Air should be PULLED out of the cowling from the rear so that cold air can get IN from the front.

Get photos and show us what you got.

Regards,

Norm

Hi Sam,

my prop is a 3 blade 70inch Warpdrive (large paddle) set at 14.5 degrees. Angle is taken at 70% of the blade lenght - not at the tip. The tip is too small to make a good angle calculation...

Did you check the Radiator displacement versus your engine power ?  My Subaru did overheat with my first Radiator... The RAD was way too small and it made the engine overheat...

Also, make sure there is enough room for HOT air to EXIT the cowling otherwise it will stay in there and heat will come up.

Finally, I do not use a thermostat in the glycol circuit, the engine warms quite well and stays in the GREEN at all times.

Got photos of your installation, maybe we'll see something you missed.

These engines set up properly are a joy to run...Yours should be too,

Regards,

Norm