When I bought my 41 it had several blast tubes (one on each mag and a couple I couldn't figure out what they were supposed to be pointed at). I removed all the "random" ones and got a significant decrease in oil temps. There were also several "loose" areas i closed up when I put the felt in. You don't want ANY of the cooling air to go around the edges of the cowl. I also made new metal pieces for between the cylinders that hugged closer to the case and fins, forcing the air to go THROUGH the fins and not around them. There was a lot of leakage from the chin opening because the duct behind it didn't fit that well. New aluminum there closed up the leaks from that. The pan under the engine was also "snugged up" to seal better. My engine always ran nice and cool until the felt popped back instead of forward and the Silicone baffle seal fixed that. I even went in and put rivets in all the little drill holes in the baffles. They probably added up to an inch hole in total.
One other thing I did while cleaning up the cowl was to put the oil breather elbow mod on and run the breather line up and over the RH side cylinders, through the back baffle and down to the normal exit point
on the center of the lower cowl exhaust. GREAT MOD!!! My oil consumption dropped considerably and I now have NO oil on the belly....NONE! It was worth the trouble just to eliminate my having to crawl under the plane to clean the belly!
One other thing I did while cleaning up the cowl was to put the oil breather elbow mod on and run the breather line up and over the RH side cylinders, through the back baffle and down to the normal exit point
on the center of the lower cowl exhaust. GREAT MOD!!! My oil consumption dropped considerably and I now have NO oil on the belly....NONE! It was worth the trouble just to eliminate my having to crawl under the plane to clean the belly!
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