Hey guys I have a 57 Bird 312 / Fordomatic. Holley 4160. I just did the heads on it. Compression is 149 -155 on all cylinders. Leak down test also good. Vacuum is is almost 19. Timing set at about 10˚. Valve adjustments have been checked several times and they are all good. Floats also checked and below sight hole. Car does run great however i pulled the plugs and noticed that the front 4 plugs are noticeably darker. I pulled the plugs because I noticed my oil seems thinner and has some smell of fuel. Also exhaust fumes are strong. I have attached 2 photos. The 2 front plugs are really sooty. I did notice that when I removed the carb to do the heads the carb gasket was wet at the front of the carb at the front barrels. Is this carb leaking internally and fuel being washed down into the cylinders?

Looks like it/s running very rich, I'd start with a carb rebuild kit gaskets etc. If front of base gasket was wet seems to be leak down. Have you noticed after engine warms up good then shut it down with air cleaner off does a little smoke come out of the top of carb? If so it's definitely leaking done a good amount. Hope this helps steer u in the right direction.

Is this an older carb that has lived through a "backfire"?
With the float levels set down as you say, especially the primary bowl - the carb would be running very lean.

 
 Steve Metzger       Tucson, Arizona

AND change the oil BEFORE you start it again.

Frank/Rebop

Bristol, In ( by Elkhart) 

Hey guys thanks for the response.
The 4160 is of the newer type with the power valve blowout protection feature. Yes I have experienced an occasional backfire through the carb over the years. It is about 6-7 years old with about 20,000 miles on it. It has never been rebuilt since new. I do have the original 4150 that came with car back in 57. It is 390 CFM. The car ran better with the 4150. The only reason I changed to the 4160 is because I had the 4150 rebuilt and took it back 4 times complaining that the car would keep running when I turned the right side air mixture screw in all the way. He checked it over and said i didn’t know what I was doing. All I did was bolt it on. turn each screw 1.5 turns out on each side, start it up and tried to fine tune it. It was blowing out HEAVY carbon out the right side. I got fed up and just bought the 4160. Upon closer inspection yesterday I noticed a fuel stain all along the bottom of the phenolic spacer just above the intake manifold gasket. Maybe its time for a rebuild

Apparently the phenolic spacers warp quite easily. The racers only use them for a few passes/races for this reason.
Maybe source a wood or metal one.