In a message dated 9/24/2003 12:08:19 PM Eastern Standard Time, tdalton@xxxxxxxx writes:
I just wanted to see if there was any found cure for this. I have a 58 Plymouth and even after placing in 89 grade gas. It knocks terribly when under load. If I go around town.. No problem. If I hit the highway, then I hit a hill.. Besides terrible power.. It knocks very loud.. Then I can still hear it as it decends.. Is this due to no lead additive? Im not sure.. So any tips would be great..
I cannot tell, from your description, just what might be knocking. Particularly saying that you "Can still hear it as it descends."
The only knock that you can affect with the octane rating of gasoline is a "Preignition Knock", and the correction for that is to set the ignition timing correctly, or retard it if necessary. This knock is usually described as a "Pinging" under load, and stops as soon as the gas pedal is released.
Can you describe the knock better? Is it a heavy pounding under load? Is it a sharp "Rap" that is only there while running at a steady speed? Is it a hollow sound?
All of these, along with the conditions that bring them on (Throttle position, etc.) will help to diagnose the problem, and even then, nothing is better than standing/sitting there listening to the actual engine.
Another thing: You say it knocks very loud. I wouldn't drive any more than necessary until the problem is found. It can get very expensive and difficult to fix, REAL QUICK!
Good Luck!
Joe Savard
Lake Orion, MI
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