I remember many moons ago my buddy gave me a Holley 850 DP carb. He said there's nothing wrong with it but you have to replace the power valve about every year. I bolted it on in place of my...now come to think of it that was the first 4bbl carb that I used on the 350. So that replaced the original 2bbl. Man, I tell you what, that carb change really woke up that 350. First time I could light the tires from a 5mph roll. I think it ran stronger with that Holley than it did with a new 750 Qjet.