Thanks for the ideas. My exhaust manifold temperatures at idle read up to and over 700 degress at idle, with the drivers side actually 50-100 degress cooler. (My 1996 3.9L Dodge Dakota exhaust manifolds read a little over 400 for comparison) The heat riser valve is stuck but in the OPEN position. The timing is about 15 degrees BTDC with about 35 total with the vacuum advance plugged. Connecting the vacuum advance made no change in timing. I have not checked the air fuel ratio yet. According to a Wikipedia article on exhaust, primary pipes too large for the application will slow down the exhaust velocity ¨Tubes that are too large will cause the exhaust gas to expand and slow down, decreasing the scavenging effect¨ Perhaps my 2.5 inch dual exhaust syste, from TTI is just too large for a basic stock 318 with the only modification a 1965 commando 273 AFB four barrel carb and 1966 manifold. My plugs are dry and slightly brown or tan and the inside of the tail pipes are a light gray. The motor runs alright and is easy to start when cold and warm but after a hot soak I usually have to try a second time. Gas mileage with a 2.93 rear end is about 12.6 MPG with mostly highway driving and 10.5 to 11.5 on windy, country terrain. Of course, with the vacuum advance out of order, that may have increased the fuel consumption a tad. I installed a mechanical water temperature gauge and checked intfor accuracy in boiling water before installation. Motor warms up to 190 degrees at a slow idle in a quick five minutes, runs about 212 driving around town for a while but if I stop at a couple of signals it quickly hits 220. But the underhood temp is what seems so uncomfortable to me.
