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I am experiencing a rattling sound when accelerating in my '67 F-250 with the 4.9l 300 i6. It is most apparent in 4th gear and only occurs when accelerating. The noise has become more prominent and the motor seems to be losing some power. Any one have a suggestion of what I should be looking for? Anyone experience this before and know how to fix?
Might be spark knock due to low octane fuel, excessively advanced ignition timing, lean fuel mixture, hot air stove valve not closing, burning oil, lugging the engine; or any number of other possibilities. Posting a video that has good audio of the sound will be very helpful in giving a diagnosis.
I agree with MPH, but specifically with the spark knocking. You might check the vacuum advance can since the sound happens in fourth gear accelerating, i.e. under a load. Check base timing as well.
Welcome to FTE and the Bumpside Kingdom!
Besides the above good information I will add one more. OLD gas can also cause it. How old is the gas in the tank?
