I have a 2007 Rubicon with a few modifications but stock motor and 6 speed manual tranny. My problem is as titled "Engine Clatter"under acceleration at 2600 rpm to around 3800 rpm it clatters really really bad. I have tried running premium gas, gas additives, and octane boosters none of which stopped the problem, improved it slightly but did not cure it. I replaced the spark plugs with OEM got better performance, almost a mile per gallon increase in fuel economy , but still the annoying clatter.

Any Ideals?

 

Wires maybe?

Your taking the steps to eliminate "spark knock" so it maybe something internal to the motor.

 

Valves knocking???

 

Thats an option but I don't know if the valves can be adjusted on these push rod motors.

 

It seems to be an ignition issue and wires are next on the list. Valve knocking oh man I hope not.