RINGKONG wrote:
this topic begs the question.
is the 4.0 a interference engine? chain breaks and valves and piston meet?
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Allow me to respond with a number of points here:
1. The 4.0 is a pretty primitive engine by modern standards. Sure, its' got 7 main bearings, and decent flow thru the head for a pushrod engine, but it's still 1960's technology, from a mechanical perspective. Since MOST of the more "primitive" engines DO NOT have an interference situation between the valves and the head, I would not worry about this issue, even though I am not positive about the clearances in the 4.0.
2. Timing CHAINS RARELY BREAK. Their failure mode is to JUMP TEETH on the sprockets.
3. If, somehow, the timing chain WERE to break, the failure would be REAL IMPRESSIVE, as the chain would "ball up" around one of the sprockets, resulting in broket sprockets, and/or a broken timing chain cover. Bent valves might be the LEAST of your worries. In any case, this type of failure is merely theoretical, as chains always STRETCH and JUMP FAR BEFORE they BREAK.