... I've seen exhaust manifolds on motorhomes glowing cherry red on a long uphill pull, many times!
Jerry
This is a factor in favor of a cast iron Fenton setup. In case you're going to tow with that rig, the manifold can get hot enough to crack. This is not just a might possibly happen someday sort of thing. I had the stock manifold crack on my rig years ago. I replaced it with a Fenton. They will definitely warp if the heat riser is stuck shut (they rarely stick open). I have a couple of warped ones.
Big gas and diesel truck engine manifolds are cast in two or more pieces with a slip joint between them to accommodate growth from heat. The short Fenton manifolds don't warp or crack in my experience. I've been running one for 25 years now. They do have a provision for intake manifold heat which works well in very cold weather though there is no way to shut it off. That hasn't been a problem for me though in running the dual offy aluminum intake. I use the thick heat insulators under the carbs. However in certain damp weather the carbs will ice up at idle until things warm up. Not a problem running down the road.
