[Chrysler300] idle WCFB quads,57 C, first few hundred miles.

Hi all,

Maybe someone has fought a bit with this; Quads rebuilt by Quad shop seem fine, everything works; engine rebuilt runs great. But, when you drive , and then stop, idle speed is sometimes high sometimes low. Feels like stall imminent, or else bang on engaging drive. I think 2 ‘vertical” idle return springs are light, probably not original , increasing that, but also beefed up with horizontal spring too, so now three springs (safer too). Pushing on linkage at idle as if stronger springs does not seem to change idle much.

On this car both carbs seem involved with Idle. I remember someone saying this changed in some years as did the “between the carbs” throttle linkage(this one is progressive, nice horizontal rod had been upgraded with aftermarket Heim end on back, cast aluminum slider part on front carb , but works identical to stock. All that seems perfect ) .

Other than soliciting comments /experience, (ram guy myself!) ---what is bothering me is that it seems that fast idle (on rear carb only—only 1 choke) is set by a metal tab touching the fast idle cam; no fast idle adjustment screw like AFB. That tab looks bendable; choke works ok, tab gets clear /drops off of face of fast idle cam when hot , as choke comes off, fast idle RPM is not far off, but fussy running/starting –but always does start. But once choke is off, that tab sort of hooks UNDER the end of the now parked fast idle cam; I think it is supposed to drop under and not touch it, but this one touches UNDER the ramp end or step inward in fast idle cam---so that hit prevents throttle shaft from turning more towards slow idle and also holds adjusting screw for idle off the place it normally touches. So this is clearly not working right..although “it works”….sort of . Idle stop screw on rear is doing nothing. But if it WAS idling with more opening, (??should it be??) it would rest OK on the idle screw..(???) I can bend that tab “down” to get clear of end of fast cam when choke off, and not bend in or out (which would change fast idle RPM) , but seems weird to me it is so close . I wonder if cam is not positioned right rotationally but it seems to be a solid rotation stop CW when choke is off all the way…and all the choke stuff seems to work ok. (all stuff mounted on that big slotted shoulder screw) Some other parts look to have been attacked, the little sheet metal stop for idle screw in particular has been mangled as if someone was trying to get the screw to touch it (would look right,---- but still not work as the hooked under other tab is stopping it) . If you do let screw touch, it only raises idle--- way too much.

While maybe self evident what to do here, what bothers me also is understanding what is front carb is doing through all this? It appears to be set up to idle too with its own idle screw and mixture screws..irrespective of choke or not , fast idle or not, on back one. It sits on idle stop all the time as linkage doe not move it, so does not matter, until like half way open throttle. What are they trying to do with two carbs active at idle? Anyone have a clear idea what is going on? Front carb idle screw obviously impacts idle , despite what is going on in back.

It would seem many combinations of idle opening and mixture between front and back would let it idle, but probably only one is correct..

And despite above stuff, not sure why speed would vary, unless just fix rear throttle stop, and readjust whole thing….. Knowing why two idles, first.

Thanks for thinking about it,…avoiding golden bending ---and golden screwdriver ! until I know , or understand, more..

John Grady