Stumped and Frustrated with a Holley 670 Hesitation

Ok, new update. I decided to pull my plugs and change them due to when I pulled a couple just a while ago they where black. Well I pulled them all, holy hell Im suprised this car even ran. In the pic the top is the front of the car and #1 being the top left and so on.

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I also changed my heat range and went to a different plug. I was running NGK ZRF6F-11, I swapped to ZRF5F-11.

I started the car verified everything was good and took it for a drive. I still have the QFT carb on the car. I got it out on the road and gave it a quick bump of the throttle. Not bad, it responded nicely. I finally got it out on the open road and went WOT. It took right off with out any hesitation. I got on and off the throttle many times and each time it was as good as the first. I turned the car around and was at a dead stop. I stomped on it to WOT, it broke the butt loose and started to get sideways on me so I let off :burnout:. Once straightened out it stomped on it again. No hesitation at all. Thru the entire throttle range. This is something that the 670 never did.

Now yes I installed new plugs, but when I put the 670 on the car it also had brand new plugs. That 670 hesitated from day one. Something with that carb ended up making my plugs look like they did above. What was causing them to turn black and carboned up I have no idea.

When I got home I pulled the #1 and #2 plugs just to take a look. These are those pics.

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Up inside the insulator is black with carbon, but I have to think that may just be whats burning off the cylinders still. I only took the car out for about a 5 mile drive. Only time will tell with some miles on this carb what these plugs will look like.

I hate so say it, but I truely do think something was wrong with that Holley and that is why someone returned it to them to start with. I really do appreciate everyones input on the Holley 670 situation. I have learned a lot about how Holleys work and how to adjust them thanks to everyone here. Sadly the 670 carb is now no longer in my possession I didnt want anything else to do with it. So I worked out a deal on this QFT with the carb shop guy. Im finally going to consider this case closed.