Holley 4412ct ?

We just find one or buy off the shelf! You can buy a upgrade racing kit that comes with larger needle and seat, power valve block off, dirt racing float for better corner flow by design, and you will need 83-86 jets if you are really on your game, plate gaskets with non stick with larger port holes to ensure max flow and then just drill(if not there) the extra hole in the center just above the shaft in the butterflies about 1/8 inch or more if needed! This will give you your clean idle back instead of having to prop them open so far so that o3/4 to 1.25 on the mixture screws gets it balanced during idle! Most allow such mods as long as you can remove the choke flap and shaft to me it is modified but any in-large-ment or cutting of the tower is usually what they mean! I never needed more to be smooth idling with both advances in place but limited with weak springs and only 10 degrees on each with live vacuum! Most chunk horses away to easily not knowing how to make good use of what they have! You might have to jet down a bit if not running my dist. upgrade as posted and at least 38+ timing at 5000 rpms with vacuum un plugged for setting the timing only! I do the same by ear and back up 2 degrees from best smooth or when you just start to hear the RPMS change and then use the light test as a reference point! This gets your burn timing matched to your timing point needed per engine design! Mine just winds up being 60 with all the crazy things I do just to win! (Don't try this at home unless fully designed to do so!!!) The weights will allow cranking at a lower timing --28 and idle --32-36 and with vacuum applied at idle will be 42-44 to burn what you throw at it when running a cool temp and it helps in the process of staying cooler, cleaner and crisper once jetting is corrected to compression and fuel! Pump gas works just fine with top lube! The vacuum drops as you open the throttle and weights take over to keep you hooked up! It rises in-tune with rpms and with no power valve to restrict flow on top end it pulls harder! The vacuum timing goes higher when lifting to clean up back to crisp of the corner with weights back working to drop enough to handle your new found horses about a car length as the car moves on the floor! Traction control by timing control! With the hundred or so extra we have with upgrades its a must or if not just weld it up and drop the timing and jets and have a power valve to have less horses when you need them most! Please ask about any thing you need! Glad to be hear for you guys as I just Friday lost my wife of 35 years and need something to do before the new car gets hear for this season!!! We never know how much time one has to post such winning knowledge! This is why I do and have made the time to do so! Good luck to all you racers, your going to need it if not following my post! If so the driver will have to excel on his own as they say they do!!!--- PS Never Idle a engine low as to the fact of shutting off too much air flow will stretch things a bit with too much vacuum produced when lifting!!! Rod bolts don't just break for no good reason even if stock!!!