Hi, we were shooting temps on our engines the other day, and noticed a hot spot on our intake manifold on one engine. The temp of most of the manifold was running around 125 degrees F, while the hot spot was running around 350 degrees F. We only have that hot spot on one engine. A friend told us that is "the furnace" -- a place on the manifold where they designed it to heat up from exhaust gases, which eventually heats the manifold and carburetor. He said since we only have a hot spot on one manifold, the other one is plugged (either accidentally or intentionally). He said they often plug the furnace on performance engines to avoid adding extra heat to the manifolds.
I don't know enough to know if what is said is correct or not, and I did not give it much additional thought until I looked at the picture of Dunroin's engines and can see a hot spot (noticable by the burnt paint color) in the same location as ours:
Can somebody make me smart on that hot spot?
By the way, we had friends in from out of town over the weekend, so we took the boat out after dark on Saturday and cruised downtown, layed over at a river-side resturant for a late-night happy hour, and cruised home after midnight. The boat ran great, our new tachs on the flybridge worked perfect, and all was good. Nice to finally be able to use that boat with some confidence we will get home on two engines!
Best wishes, Curt...
1967 fiberglass 38' Chris Craft Commander Sportfisher with twin 427 CID 300 HP engines.
