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You are correct...the plug wires for the front cylinders do indeed run behind the engine mount. Some folks have managed to snake new wires thru by taking the terminals off first, then sliding the wires behind the mount, and then re-attaching the terminals. Some also un-bolt the mount, and jack the engine up a bit to help.
You might also opt to just run the new wires over the tops of the valve covers, but you run the risk of burning wires on the exhaust, and creating ignition noise in the radio....which is why the wires are covered with the shielding to start with.
One other option is to pull the engine out....much easier to do the wires then.
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Joel Adams
C3VR Lifetime Member #56
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