It looks like you're new here. If you want to get involved, click one of these buttons!
Diagnosing Engine Noises - Too Low Octane, No Lead, etc.
Specifically, what could be called deiseling or what I call valve clatter while accelerating, but only when the engine is fully warm on a hot day.
Also, can someone explain how knocking or pinging would sound different from the above?
Are they caused by low octane, bad gas, dirty valves, bad timing or ignition, no lead gas, or something else?
Bought a 67 Ford with a 390 2 barrel, 9.5 to 1 compression, and 31,500 original miles. When I test drove the car, it was making what the seller and his mechanic said was a "dieseling" sound, but only when accelerating; it sounded perfect at idle.
They replaced the distributor, condenser, and points, and that seemed to eliminate the problem. I know those parts were replaced, as I saw both the new and the old ones. The car ran and sounded great after that on the 5 mile test drive. However, when the engine is fully warm on a hot day, it still makes the noise, though much less so. I ran 93 octane with some valve cleaner in it, as the car has been barely driven in 8 years.
I just put in 89 octane, and the noise is worse, but again only on acceleration after the engine is fully warm. I am startin to put lead substitute in it, but does the timing need to be revisited?
What octane would a 1960's 9.5 to 1 engine need?
Since this is relevant to non-computer controlled cars, I thought the knowledge here would have suggestions.