Hi, I'm about ready to maiden my 27% Cap with a Brison 3.2. The engine is installed inverted with 4 of the 7 cooling fins fully exposed outside the cowl. Would it be wise to seal the 2 openings in the cowl cheeks for more direct air flow over the cylinder? The timing linkage on the engine would make it difficult to install a baffle. Suggestions?? Thanks

I would say no, do not close any openings. 4 of 7 fins is not enough to properly cool the engine. Make sure you have 3 times the opening area for air to flow through and escape from the engine compartment.
I have a friend with this same setup, plane and engine, flys great, but he did have to go back and open up the cowl behind the exhaust to keep it from running hot.

What I did on my Extra with a Brison 3.2 is to open the front area for the entire engine to get air and then block the openings in the cowl. I found that this allowed the air around the carb to be stagnant enough to get a reliable running engine.

I used to have a Lanier Cap with a Brison 3.2 mounted like you described and had no problems with cooling without baffles in the cowling
The cowl cheeks were open and I also had plenty of open area around the exhaust pipes (pitts type) to alow plenty of airflow.
I would not close the cowl cheeks, these actualy work pretty well to aid in cooling .
Having 4 of the 7 cooling fins exposed should allow adequate upper cylinder cooling without cooling to much. (especially in cold weather)

I went ahead and opened up the front a little more and now I have 6 fins fully exposed. I'll leave the cheeks open. As far as the rear exit opening, I trimmed it to the flange which I'm told creates a low pressure area to aid in cooling. The only thng I'm worrid about is the fact that the Pitts (can) eats up alot of the rear exit

You will appreciate the cooling, just make sure you don't have too much air flowing around the diaphram hole of the carb.

I suggest that you read this thread. It talks about cooling.

Ken

http://www.rcuniverse.com/forum/ZDZ4...2035926/tm.htm

Thanks, That thread is what caused my concern.

I have a Corby Starlett. Made a glass cowl for it and left the cheek cowls closed. Would run 4 or 5 mins and quit from overheating. Opened the cheek cowls, all is fine.

Theirs more in the ZDZ 40 overheating thread.