[DanEC]

Assuming that Ford intake is like most Ford dual quad intakes, there are other issues. The carbs are reversed and the Holley fuel level sight opening in the primary bowl is higher than in the secondary bowl. Since the primary bowl is on the rear on a 2x4 427 intake, if the float level is set right at the bottom of the sight opening you stand a good chance of flooding your engine on a hard stop and killing it. And if you lower the fuel level too much in compensation, under hard acceleration fuel stacks against the rear of the bowl and risks starving the primary jets. Issues you don't have with a normally mounted Holley carburetor.

I even called Holley up once and asked them what changes/setting they would recommend for Ford reverse mounted carbs. Only response was "what" and "huh". The old Ford guys install a Holley whistle vent extension in the vent hole at the top of the Holley metering plate. That helps avoid flooding the engine on hard stops and I've installed those on my Holley 1850s. They also install jet extensions in the primary side to prevent the jets from being uncovered by fuel stacking against the back of the float bowl. I looked into this and Holley makes a special float for it on a Holley 4150 carb. But on the 1850 with the nitrophyl floats, huge notches would have to be carved in them to clear the tube extensions. Some guys on the FE forum said they have done so but didn't look like a good idea to me so I didn't try that.

So in short I put in vent whistles on my primary bowls and dropped the float level down a little bit below the sight port. I set the secondary float levels at the bottom of the sight port.

Your set up may need to be played with a little more as a 4 deg slope on the carbs sounds greater than my 427 low riser dual quad intake. From memory I think my carbs are sloped about 2 degrees or something around that. Wedge base plate adaptors are available from a variety of sources to adjust the carb angle, but the lowest angle one I've seen is 5 degrees. Supposedly Cobras were equipped with these originally but I don't know what angle the original ones used.