VERY typical problem with the m103 engine. Look all around and below valve cover gasket, and just under the distributor cap for signs of oil, probably need to clean the engine with some degreaser first. This engine will usually leak from these two spots when running, so oil does not really collect in the underpan or on the driveway.

p.s. A search should bring up a ton of info on this.

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headrivenoise... listen.