I just put a 670 Holley Street Avenger on my 360 and the only adjustment I had to make as to set the idle stop screw for the idle speed. Monkied with the mixture screws but when all was said and done they were back to where they were out of the box.
The throttle response is awsome and on the top end, based on the butt dyno, it is as good as the 3310-2 Holley 750 i have or the Barry Grant 725 Road Demon. An interesting observation I made about this carb is that the primary venturis are smaller than the secondaries even though the throttle blades are all the same size. This likely has a lot to do with the awesome throttle response. A little of the spread bore design philosophy in a square bore carb.
I put about 100 miles on it this weekend and I am absoultly tickled pink with this carb. And the jets are close enough that I won't be doing any jets changes unless I get a wide band O2 sensor or get the car on a dyno.
FWIW, the only Holleys that I have had any issues with are the ones I picked up used and do not know the history on. The new ones have been trouble free and have required a minimal amount of tuning to get them running well and have not required any adjustments over time.
