Of engine tap, but in a narrow rpm range, and other conditions

Factual Questions
1

vehicle: 2001 Dodge Dakota Quad Cab
engine: 40k on 4.7 OHC V-8 hooked to 5 speed auto

problem: between 2500-3000 rpm, as load builds (that is I’m accelerating, not just cruising or reaching this rpm casually) I hear what sounds like various valve tapping, rattling. After 3000, it disappears.

Modest load, and modest to modestly strong accel reveals this sound consistently.

Full throttle acceleration does not produce this sound - and that perplexes me but gives me a false sense of security (possibly).

I had a hoot one time when I drove around for 1-2 mins keeping it over 3000 rpms and running it to redline a number of times as a test. It’s a smooth engine, with no sounds or complaints. This engine would love life in a light car with more aggressive timing, but I digress.

Regular oil changes, yes. Really mostly hiway drives. About 13k per year. No tune up yet, but Dodge reps go out of theiw way to support the owners manual 36k tune up.

Only mod to truck is a dual-outlet set up - a mock dual exhaust which makes it louder than most people like.

Any ideas? Would overshooting a tune-up (new plugs more or less) create a scenario like this??? Or is there a valve issue???

2

Sounds like it might be pinging. You could try a higher octane fuel or switching brands and see if that changes it.

3

I must admit I did not do an octane test. I thought concerns of pinging vanished with electronically controlled ignition/timing/ etc. etc.

4

I vote spark knock or late detonation. Either way, change the plugs and see if it goes away.

5

I would try a higher octane before anything else.