'88 460 Backfiring

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Aug 26, 2005 | 12:19 AM

grantorino

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Joined: Aug 2005

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'88 460 Backfiring

My '88 F-350 460 5 speed has started to occasionally backfire when driving in gear without giving it gas (such as going down a pass, using the engine to slow me down instead of the brakes) I wouldn't be so concerned but it's a really violent explosion which sounds like it's coming from the muffler area (it sounds like a big shotgun). At first I was told it may be a plugged AIR pump, but then I discovered the AIR pump has been disabled (the pulley to it is even gone). Someone else suggested it could be due to too many exhaust leaks at the manifold. I do hear leaks at the manifold if I'm climbing a hill or giving it a lot of gas. The engine has a fresh tune up and all new filters (fuel and air). It runs great except for the backfiring. Anyone have any ideas?

Thanks!

Aug 26, 2005 | 01:45 AM

Bear 45/70

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Joined: Mar 2004

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From: Union, Washington

Sounds like it has either gotten too rich with age (maybe) or you blew the power valve (probably) in the carb. Also be a good idea to recheck the timing and to make sure the vacuum advance is connected to the ported nipple and not the manifold.