OK. Lets start at the top and fix this thing. > Model 4160 is a very general model identification. The exact model (in non-Holley speak) is the "List number" (Holley speak) stamped on the choke tower. It's probably an 1850-? but maybe not. Find it, post it up. > There's two ways to approach this. Some combination will work for you. a. Follow a set of directions, procedures and settings. This worked fine with factory stuff, and sometimes works OK with aftermarket. b. Understanding how it works and then figuring out what changes make sense. The best intro to how Holley carburetors work is probably the first chapters of Urich & Fisher's Holley Carburetors and Manifolds. Buy a used older edition - you don't need Holleys promotional of their EFI etc. On-line, Chrysler's Master Tech series is a good option even though not Holley specific. Follow the link and see 1966 "Carburetor Fundementals", or the slightly revised version in 1970 (adds smog carb and Holley power valve info). If you had good performance before, then the model is not the issue. Something has changed. Please check. Although I don't think this is it, it is important. Write down the timing and rpm. Make sure it (timing) advances with rpm once its over 650 or 700 rpm. Reconnect the vac advance. Not a mistake at all. There's really nothing to 'rebuild' 99.5% of the time. Its just a matter of cleaning and installing new gaskets; then checking the dry settings. Send it out when things are broken, it needs refinishing, and/or is so dirty or corroded it needs a ultrasonic cleaner and other measures. Yes. Please check this. I agree with Willrun. Overfilling the bowl is most likely culprit. If you can, after the engine is stopped, look down the carb and see if you can observe fuel coming out of the vents, or the boosters. If it is, there are only two possible causes. Inlet system is letting in fuel when it shouldn't, or the fuel pressure is higher than it should be. If the fuel pump and lines haven't changed, then start where you should alsways start in setting up the carb - float levels. However there are other ways excess fuel can end up in the intake manifold. One is incorrect or failed power valve gasket, or damaged power valve. There's others, but these two are where to start. While the bowl is off, look at the acclerator pump check valve and diaphram. Uh yes but you've changed carbs, so all bets are off. Something may be different with the replacement. Jets could be removed and it still should run fine up to 40 or 50 mph. If the choke has been fully opening, and the timing is working, the adjustment sequence should be float/fuel level, then idle throttle position, then idle mix. Only after those are good, adjustments can be made forthe higher speed (jets) and for accelerator pump (rapid throttle openings from near closed throttle). The last bit almost sounds like vapor lock or running low of fuel in the bowls or in the accelerator pump... I say that because you close the throttle and the engine returns to life. The power valve opens an enrichment circuit for full power situations. It only opens when close to wide throttle and engine is under heavy load or acceleration. Engines run somewhat rich at idle but then leaner off idle and under part acceleration. But near maximum accleration they need a richer mixture again. See the book and/or the master technician pamphlets suggested above.