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Thread: Continental A75 power loss, BIG Mystery

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  1. #1

    Join Date
    May 2014
    Posts
    13

    Continental A75 power loss, BIG Mystery

    I run in my J3 replica one Continental A75 -9, feed by a Stromberg carburetor and 2 electronic ignition.
    With the wood propeller it fly leveled fill open throttle at 2450 rpm, maximum for this version is 2600 rpm. It use to has a great performance compared to the 8 others J3 there is in our airpark.
    220 hours after tbo, I notice a power loss and maximum leveled rpm is now 2200. The takeoff roll is bigger, climb rate is poor and maximum ais lower, sound of the engine has changed a lot. I have 4x1 with no muffler exhaust, it is louder than regular J3 muffler, but is different even from the ground, to silent !
    On break maximum rpm is 2150 and on takeoff roll drops to 2100 !!
    I look every little thing possible; at least what I could image…

    • Air induction filter, flown without filter
    • Carburetor, checked twice, changed one
    • Induction pipes and connections
    • Gas feed, gascolator, roses
    • Changed avgas
    • Changed ignition system, new plugs, cables, coils
    • Compression check 80/78 all cylinders
    • Open the engine and check camshaft, tappets, push rods, all clearances
    • Test 3 different propellers
    • Checked ignition time with time light
    • Engine run smooth as ever, mag check drop is less than 25 rpm as ever with electronic ignition
    • Muffler is clean

    However, no results…. Any clue? I appreciate any help
    Thanks all
    Last edited by Tasca; 04-22-2025 at 01:19 PM.

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