Just thought I'd post this info, even though its a Ford FE 416 (390 with 428 crank) work truck.
F250 4x4, 4 speed, 4.56 axle gears, headers with 1.75 primaries and 24 inch by 3 inch diameter collectors then resonators and 2.5 diameter pipes thru Dynomax super turbo mufflers. Fuel mixture set using O2 sensor from idle-transfer ports-mid range-and secondaries.
Put a Comp XE256 cam. Specs are 256/268 with 212/218 at 0.05, 110/106 lobe sep. and 42 degrees overlap seat to seat and 5 degrees no overlap at 0.05 lift. Engine had somewhat lumpy idle at low speed, pulled real strong at mid-upper rpms. What bothered me was the exhaust ports and headers were thickly coated with black unburned fuel deposits. I mean coated. I figured there was too much intake exhaust overlap, even though the cam was for 1000 rpm so they said.
Swapped the comp cam for a Lunati Voodoo with specs 250/256, 207/213 at 0.05, 112/108 lobe sep, and 29 degrees overlap seat to seat with 14 degrees no overlap at 0.05 lift. So this cam has less overlap, and was rated at 800 rpm.
Exhaust ports are now white/tan, some a little black showing up. Engine has similar bottom end, does not have the top end it used to but that is fine by me.
Can't really tell if the gas mileage iimproved. The truck weighs almost 5400 lb empty, usually gets about 9 or 10 mpg fully loaded or empty.
