engine knock at high speeds

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Apr 11, 2003 | 09:48 AM

greenhornet

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Joined: Jul 2002

Posts: 24

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engine knock at high speeds

I've got a 79 f150 with a 460. I took it out on the highway yesterday (which I don't do very often) and drove it at about 65 for about 30 minutes. About half way through driving there was a loud knocking sound coming from what seemed like the direction of the engine. If I let turned it off and let it sit for a couple minutes it would stop until I got to around 50 mph and it would start up again. Any suggestions as to what could be wrong?

Apr 11, 2003 | 10:26 PM

trinogt

Cargo Master

Joined: Apr 2001

Posts: 2,364

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From: Eustis FL

engine knock at high speeds

Could be a rod bearing letting go. Other knocks can come from too much advance spark timing, carbon build-up. Could also be cause from a stretched timing chain, and a timing light at idle won't be accurate for timing when moving later on the road.
Either way, it should be checked out...
Mark