Hard miss at startup, then smooth running?

Too much choke?

Mike

Mike could be right! The Holley Choke should NEVER be FULLY closed. When the engine is cold AND the DISENGAGEMENT of the FAST IDLE CAM(and choke plate)is activated(by pumping the accelerater 2 0r 3 times),The choke blade should close to a MINIMUM gap of 1/8" (.125 Inch). If this is not happenning you must first disengage and then adjust the angle of the choke plate at the choke heat coil housing. Usually A Round Black Plastic cover with "Tick" marks around the circomfurence and secured by 3 screws. Loosen screws and turn housing until you have acheived the 1/8" gap.(This adjustment is made with the Engine OFF and COLD. Make sure you have completely released the "EXCAPEMENT" by actuating the Primary Butterflies). Ofcourse retighten the screws. NOW when you start the engine the gap may open a little, or when the engine is revved, this is normal. The Plate should NEVER be sucked completely closed. As Mike suggested, to much choke (completely shut plate) would account for you troubles, Bad COLD Idle; AND would/Could cause Fauling of your spark plugs. If you have NOT pulled your plugs to check for correct burn mixture, or to just see the condition, you must do it now; or else you will never know if any may be causing a miss. Although, Fauled plugs will NEVER correct themselves just by heating up. This can be your oportunity to install a NEW set of plugs. I use Champions with an Electronic Ignition. Good-Luck with it! Marlin.

Let US know of your progress! As there are probably 50 different causes of a "Hard Miss" at start up. Remember, It has to be either 1. Fuel 2. Spark 3. Mechanical OR ANY combination of the three. 100's of operations must happen perfectly at the exact time for that engine to just sit and Idle like a purring pussy Cat. Keep us informed, Marlin.

Thanks all. Will inspect choke opening at cold setting. This has been a gradual problem with things getting worse. Plugs are new. Heads are rebuilt. Holley is new. All worked fine 500 miles ago. Perhaps the
float level is too high? Could fuel be condensing in the high rise roush manifold after cool down? Strange.

Thanks. Greg

Check your timing, too. Too much advance (or retard) will cause hard starting. While you're under the firewall cover, check your harmonic balencer for slippage before you reset the ignition. These debond over the years, resulting in movement of the outer ring. So an unwary owner rsets the timing to the erroneous mark shown, and then wonders why the engine runs really bad. One owner recently found his 32-yr-old original outer ring laying on his water pipes....a total failure.

I just put on a brand new Holley Avenger and the same thing was happening right out of the box. Holley even sent me a new choke housing to see if that would fix it. I tried every increment on the choke setting every morning during cold startup and still no luck. I returned it to the local auto parts where I bought it and exchanged it for another one. Still the same thing! I figured it was something else not carb related at that point. Turns out that I had to adjust the idle-mixture set screws on each side of the carb using a vacumm gauge. Now it starts up fine. I did however install a heater sensor on the intake manifold that opens the choke at a slower rate as the engine warms up. The choke would open a little too quick even on the richest setting. (Counterclockwise). This may not have nothing to do with your problem, but you mentioned you put a new carb on. For anyones info, the sensor installed is available from Holley. It's held on by one of the intake bolts, and has a wire that connects to the negative side of the choke.