I’ve always heard they are quite rare and most that bought them could not get them to run properly and gave up on them. I’ve just completed my 2 carb setup with help from Drew Pojedinec. Hopefully this set up will work out! I’m excited to try!
Hello 67 GT500#1594,
You may want to revisit the position and mounting of the Drivers side Carburetor on your setup. The dual 8V top was designed to have the driver's side carb mounted backwards. As you can see the dips (clearance notches oriented in the center) (see pic, top is upside down in photo) for the carb levers and linkage.
The reason is (as designed) the passenger side carb's primary venturies will feed the forward cylinders. When mounted correctly, the drivers' side venturies will feed the back half of the cylinders. The inside of the manifold is like a giant bath tub. (see pics).
Unlike the single 4V arrangement, That top has distribution walls (see pic) to evenly distribute air/fuel mixture.
Attempting to run your setup as is, you will experience lean conditions on the back half and erratic surges once you open the secondary's.
The linkage assembly should run in between the two (2) carburetors. Passenger linkage rod should "pull", the driver's side linkage rod should "push". (see pic, rod lengths are short in pic for discussion reasons)
I thought to inform you so to avoid a future headache.
Cheers,
~Earl J