I keep getting a bog or stumple when at idle- low rpms when about to give gas to increase rpms or speed,like it chokes and clears thereafter?what the hell causes that? Thanks
Man, that's a pretty vague description. What kind of shape is the carb in? Recently rebuilt? Old and crusty? When did the problem start? What motor/car is it on? Does it stumble under load? If the carb is in top shape, then check: 1. Accel pump arm adjustment 2. Make sure fuel is actually coming out of the squirter at the right time. Might be a clogged passage, or broken pump diaghram. 3. Make sure the throttle blades are not too far open at idle. They should only reveal about .030" of the transfer slot at idle. 4. Vacuum leaks? 5. Blown Power valve? Without more info it's hard to go further. Have fun.
No the carb was bought new and never tampered with,it`ll even do it at idle and under loadits like a slight choke and then clears right away,i dont see how the power valve would make it choke? Thanks
If the power valve was blown it will richen the main circuit all the time and might cause an over-rich condition at low RPM. It was just a possibility. I would check the accel pump linkage and make sure there is no slop in it. Loosen the nut until there is some free play, then adjust it until all the slack is out. You should be able to barely move the throttle linkage and get a little fuel out of the squirter. Also, don't forget the rear linkage. If you're running a big cam you might have opened the primaries too far at idle. Do the idle mixture screws have any affect on the idle quality? If not, the primary blades are open too far. Refer to my previous post on how to adjust. If you need more air to make it idle, open the rear blades to about the same amount. The rears are adjusted from the bottom with a tiny set screw. Adjust the idle mix screws to about 1 full turn out from their seat, then adjust equally to get the best idle. Do you have rear idle mix screws? Adjust all four equally. Main jets will have a slight affect on idle mixture. Does it still have the factory jet sizes? They're usually pretty close if the carb is the right application. Check your float level. Adjust so fuel is right at the checking hole at idle, with the engine running. Double check your timing. If that doesn't help, you may have an internal problem. Diagnosing carbs over the web is very difficult. Have fun.
no its not a 4 corner idle,i will check all that you said and see from there,no black smoke coming out of the exhaust and it doesnt seem to be running rich,i know its hard to diagnose a carb off the net,i never fooled with the carb too much,i did adjust it to best vacuum with a gauge,lets say its idling and i go to give gas by hand from the front,it`ll have a light hesitation or choke for a split second then clears immidiately as i`m increasing the rpm`s.
Yeah, that sounds like a momentary lean out. Probably linkage, or primaries open too far. Check everything just in case. Your sig says you own the black GS that was in PHR in Feb. Cool car. I really liked it. Have fun.
Hey George, Check and make sure your getting squirt out of your boosters just as soon as move the throttle.... If not adjust it so your getting squirt with any forward throttle movement..... If you are, chances are your 455 needs more of a squirt. by default, the car probably has a #33 squirter on it. When I was running NA on my 462, it needed a #40 squirter to keep the stumble away........
Rich,i called Holley and they told me the same thing,i took out the 32`s that were in there and i had 35`s floating arond so i put those in,i`ll see how she runs,if she still does it maybe i`ll go with bigger ones. Thanks
