Contour Enthusiasts Group Archives Forums Modifications 3.0L Duratec I finally know why I blew my 3.0L

Originally posted by procyon:

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Originally posted by bnoon:

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The valvetrain has very little resistance on it when assembled properly.

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Brad, in reality the timing chain is a extremely stressed component in the engine. True, there isn't much resistance from actually turning the cams. However, I know you timed your engine and you must have felt the large amount of torque needed to open the valves by turning the crankshaft. (and no there isn't much compression resistance when you just turn the crank a few degrees to line up the chain)

In addition to the above, the chain is subject to large torque pulses as each cylinder fires and applies torque to the crankshaft. The damper and flywheel do provide some help but it's still not an easy life for the chains.

Still, I have not seen any issues *in my experience* with the Duratec timing chains (small or large size). I would have to guess that PuckPuck's failure was due to some other cause than an inherent design flaw with the smaller pitch chain.

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While I agree that the cam chains don't lead an easy life, I don't agree with the "large amount of torque needed to open the valves by turning the crankshaft". These engines are far easier to turn over, even with the plugs in, than say any pushrod engine I've ever come across. "Very little" was used as a relative term. Superior chain design compared to those older designs lead me to the same conclusion about Puckpuck's failure.

Originally posted by procyon:

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They are all numbered. On a 2.5L the LH head cam caps will be numbered 1L, 2L, ...9L. The RH caps will be 1R, 2R,...8R. LH head has one extra cam cap on the intake cam for water pump drive.

There are no measurments stamped on the heads.

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Ahhhhh, how could I forget about the 1L, 2L, etc. Sorry 'bout that gents! There are measurements cast or stamped into the lash caps though... I was sure of it...