I'm having an issue with my recent engine swap from an o-320 with a fixed pitch to an o-360 with a constant speed. Initially the increase in performance was what I'd expected (better rate of climb ...1600+ , better top speed ...almost 180 kts at 5000'), but recently I've noticed a substantial decrease in performance .... Only seeing 800-1000 ft/min and top speed of 144 knots true). I initially thought I was having some instrumentation problems, until I noticed I was only getting 2490 rpm on climb. I adjusted the stops to get 2700 and took off next to a friend with the same engine/prop combo in an RV4. Now I know a similarity equipped 4 will always out perform a 6A, but this was embarrassing! He said that to stay with me at take off he was at less then half throttle. Our indicated speeds were within 2 knots once level at around 3000'. He was at 19" manifold pressure I was at 27" (wot indicating 144kts). I had to leave town immediately after this run (possibly too embarrassed to show my face at the airport ) , so I had no chance to pull the cowl and check things out. I have been unable to get it out of my mind. I can come up with two possibilities... Timing has slipped and is way retarded or the lobes on the cam on my new rebuild have gone the way of the dinosaur. A few things about the engine.... It was rebuilt by an a&p and sat pickled in a dry climate for 9 years before I got it. I did find some very mild corrosion in the engine upon pulling the valve covers and a few small spots on the timing gears, hence my concern that the cam may be grinding itself flat. As far as the timing goes, the engine is equipped with an electronic ignition and fuel injection system. The timing is picked up using a unit made by Electroair (MTH) that mounts to one of the mag locations. It is adjusted the same as any regular mag. I'm thinking (hoping) it's lose and has slipped. I'm sure some of you are thinking fuel after I mentioned the efi. I have a wide band O2 meter (yes I know the life span is shortened running 100ll) and it was indicating 10-10.5 to 1 on climb and 12.5-13 to 1 during the 144 kts run. Additionally my fuel flow was indication 17 gal/hr on climb and 14 gal/hr on the 144kts run. The computer uses manifold pressure to meter the fuel, so I'm thinking with these numbers timing is likely the culprit. Have I missed another possibility? I know I should just check the timing and then the filter for metal, but I will not be able to get to the hangar for a couple more days and this is driving me crazy! Any ideas????