FL Flat Head, I'm just about winding up my testing of fuel boiling in 85 plus outside temperatures. We have had about 85 temperatures for the last 3 days and I have driven about 75 mile in the afternoon each day. Here's a list of temperatures I got today. At start= fuel tank 78, fuel pressure 3 3/4 lbs. Drove 35 miles and checked temperatures. Left head 181, right head 183, carb bowl 106, intake manifold at base of carb141, fuel inlet pump 116, fuel pump 117, gas tank 99.
Stopped for 15 minutes and returned differant route 40 miles.
Arrived back at shop. And taested as soon as stopped.
Fuel pressure 1 3/4 lbs.,Left head 168, right head 169 going into the wind comming home runs cooler, fuel pump inlet 119, fuel pump 122, carb bowl 107, carb base 115, intake where carb bolts to 140, Intake itself 157, fire wall bottom 140, fire wall top 119, fuel tank 103.
oil pressure at idle 15 and 40 at speed with 15/40 Cummins valvoline blue diesel oil.
The fuel line is clear of the exhaust and no heat from the pipes transfering to the tank. Heat to tank comming from hot roads. Fuel line removed from fire wall clamp insullated with pipe insulation from below fire wall to pump. The 125 + heat from the rear of the engine heats the fire wall and the steel line clamped to the fire wall heats the fuel line to 125 if clamped. Without insulation the 125 heat gets the flex line brass fittings to 125. The fuel line is 2"s from the fire wall. The carb has a vented 1/2" phenolic spacer from Bob Shewman or Gadgiteer between the carb and the intake manifold. .020 SS tabs with 1/4" holes between intake manifold and top of gasket reduceing but not eliminating the carb heating. The only problem area now is the 160 degrees on the intake manifold about 5/8" below the fuel pump. Jambed foam insulation somewhat under the fuel pump and had less heat on the pump today than the last 2 days. I'm going to get Gadgiteer to make me 1" phenolic spacer for under the fuel pump stand to insulate the pump from block heat and give me 1 3/4" clearance under the pump. Will need to make the push rod 1" longer. This should take care of all the problems with the 10% gas mix. When this gas gets close to 125 you start to get problems. G.M.`