View Full Version : 496ho lean burn?

06-06-2011, 11:56 AM
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.

06-08-2011, 06:21 PM
A stock 496 should run 5250 at wot if set up right.:)

06-08-2011, 06:35 PM
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.

06-09-2011, 03:18 PM
I appreciate the help. The borescope and a compression test hopefully will put my mind at ease.