[Formulajones]

Doubtfull. I have our 69Z idling around 1100 rpm (manual trans) and daily drive it that way. It doesn't care as far as engine temps go, I mainly have it idling that high to help the engine produce a bit more vacuum for the brakes since we are up at 5000 ft elevation.

The biggest affect on idle temps I've found is whether you have vacuum advance hooked up to a ported source or manifold vacuum. Manifold vacuum, with the advance working at idle, has had a much more noticeable difference on engine temps, running cooler, in that configuration.

The trick though is having that vacuum advance dialed in so it's working at around 6 inches of vacuum and all in by 10 inches or so, and only adding about 10-12 degrees. I modify them to do so. If you run a can that adds 20 degrees and doesn't start working until 12 inches of vacuum it's not going to do anything for you at idle when hooked to manifold vacuum.