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Thread: 496ho lean burn?

  1. #1
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    496ho lean burn?

    How long does it take to lean burn a 496? I have a 496ho and a bonehead mechanic. Last summer, I noticed the engine was only getting 4300-4400 rpms turning a 25p mirage plus. Usually, it does about 4800. The engine idled a little rough adn the IAC was pretty noisy. I took it to my mechanic who found nothing wrong with it and told me the fuel pressure was fine. After 2 months of the same problems, I eventually lost trust in my mechanic and checked the fuel pressure my self. Turns out I was only getting 24lbs. I replaced the high pressure fuel pump and cleaned out the fuel system, which solved the problem. Now the engine is turning 4700-4800 rpms, fully trimmed. I haven't done a compression test on the engine yet. How robust are these engines? Is it likely that I damaged the engine? I probably put 15 maybe 20 hours on it last summer.

  2. #2
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    A stock 496 should run 5250 at wot if set up right.

  3. #3
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    You should hopefully be OK.
    I would do that cylinder compression test to be sure all is as it should be.
    If you can get your hands on a bore-scope you could actually view the tops of your pistons to be sure none were burned & damaged.
    Harbor Frieght Tools sells these bore-scopes for reasonable money.
    I also have a high-quality bore-scope and use it often to inspect engine & gearbox internals.
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  4. #4
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    I appreciate the help. The borescope and a compression test hopefully will put my mind at ease.

    Jim

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