My 26 coupe is running a non vapor NH carb and intake. I'm still experiencing hot exhaust manifold, not as bad since I open the spark up way more, but still happening. I'm wondering if the fuel isn't vaporizing fast enough which is why I'm getting burn off in the exhaust manifold. do you think installing an NH carb heater could help? It could reduce fouling of no.1 plug as well from what I've heard.
Try it and find out. it will not hurt anything
Make sure your timer is properly timed. Your ignition may still be retarded, even though your lever is all the way down.
You may also be running too lean, not too rich. That will cause an overly hot exhaust manifold.
Erik is on it, it sure sounds like ignition and/or a mixture adjustment.
Good advice. I've adjusted the needle in and out and have it where it likes it best once warm, which seems to be about 1 1/8 turns out from bottomed out. I as of yet have not taken the timer off since I bought it. Looks to be a stock Ford timer. Perhaps some disassembly, cleaning and oiling is in order.
I have a 27 with a Kingston L4 with none of the issues you mention and no stove pipe just an air filter so I'm with Erik on this one
How smooth does the engine run and have you checked the spark plugs and compression? If unburnt gas is getting into the exhaust manifold it is burning there and causing it to get hot. The compression should be between 45 and 50 psi with a standard head and should be even on all cylinders. If you have a stuck exhaust valve you could be blowing the fuel mixture into the exhaust upon compression stroke. Also If one spark plug is not firing, the fuel mixture would be forced into the exhaust manifold on the exhaust stroke.
The exhaust valves are probably opening late and closing early keeping heat in the engine. Time the valves, intake and exhaust, with the Piston Position method.
Leaving all other factors exactly the same, installing the heat shroud will richen the air/fuel ratio. Since excessive combustion heat is usually caused by a lean mixture, installing the heater could help. So would turning the mixture knob a little richer. I'm basically lazy, so I'd try just running a slightly richer mixture and see what happens.I'd also check for a carb gasket or intake manifold leak.
I would still make sure the timer is properly timed.
I'm not talking about cleaning and lubricating it.
I'm talking about setting it up correctly.
Hope you know what I mean.