I agree that timing should be checked and note that you shouldn’t have any vacuum advance at idle (that will give you all sorts of grief). Your vacuum seems very low, for any engine. I’d also check for a vacuum leak. When you say idle was bumped up, are you using the factory way of adjusting the air screws or are you opening the throttle? Might be best to start the tuning procedure from scratch again using the factory manual (for the 300C). A few years back I rebuilt the 2 barrel stock carb on my wife’s Mustang to factory spec. But when cold there was a slight hesitation when taking off that even my wife noticed (grrrr). I double checked and found I had put the accelerator pump linkage in a wrong hole for that engine/model (no excuse - but there are 8 possible combinations!) After fixing that it was perfect. Believe me that the factory engineers did know what they were doing. However, if you alter the cam, all bets are off. Might need a bigger shot as suggested before. Good luck Henry From: chrysler-300-club-international@xxxxxxxxxxxxxxxx [mailto:chrysler-300-club-international@xxxxxxxxxxxxxxxx] On Behalf Of William Huff
Sent: Sunday, 8 May 2022 1:15 PM
To: John R. Cote
Cc: gary.gettleman@xxxxxxxxx; garythepartsdoc@xxxxxxxxxxxx; rfmelton@xxxxxxx; chrysler-300-club-international@xxxxxxxxxxxxxxxx
Subject: Re: {Chrysler 300} Need more fuel! Initial Ignition timing also has an effect on vacuum. Just a question........... Why change a cam from original to a problem? Am I missing something? -----Original Message-----
From: Gary Gettleman <gary.gettleman@xxxxxxxxx>
To: Gary <garythepartsdoc@xxxxxxxxxxxx>
Cc: Ray Melton <rfmelton@xxxxxxx>; 300 Club <chrysler-300-club-international@xxxxxxxxxxxxxxxx>
Sent: Sat, May 7, 2022 7:19 pm
Subject: Re: {Chrysler 300} Need more fuel! Gary, The more information I get the more confused I become. Leaning towards replacing the isky cam that hot heads recommend and going with Clay Smith cam that Rob Kern likes. Have low vacuum between 6-8 lbs and that's after idle was bumped up. With a No. and letter drill set you can dill jet to any size you need. Sent: Saturday, May 07, 2022 12:25 PM Subject: Re: {Chrysler 300} Need more fuel! Ray, Thank you for your way over my pay grade response. Mechanic is very talented and has some very high $$$$ builds to his credit. That said, his main business is high end Resto Mods. Did a buddies '41 Cad coupe on Art Morrison frame with 2021 Cadillac Hot Engine and 8/10 ? speed tranny. Very High end builds, yet he will work on old Detroit iron like our beloved 300's. I like your suggestion re the service bulletin update and will start there and let you know how it goes. The once "Golden State" (but not so much any more) of California. Sounds like it could be insufficient accelerator pump shot. Which jets is he suggesting to be changed, and to what size? How did your mechanic decide which jets to change and the new size - anything scientific or just WAG? How will you find those jets for such an obsolete carburetor? Even if jets for the later Carter AFB would fit, is the internal fuel/air flow circuitry the same as for the WCFB? Since the 300C was originally intended to run on only one carburetor at low RPM, you may have upset the A/F ratio right off idle when you converted to synchronous (non-progressive) carburetor function - going too lean because of the unintended extra airflow from the other carburetor. Have you incorporated the carburetor modifications recommended by Chrysler in Technical Bulletin #364 of July 16, 1957? That may/may not help, but it couldn't hurt. I had Jim McGowan do that mod when he restored my carburetors - excellent workmanship and results! Depending on the elevation where you primarily operate, you might also want to consider different metering rods, too, although that will not affect your off-idle stumbling issue. Ray Melton 300C in New Mexico ********************************************************************** On 5/7/2022 12:31 PM, Gary Gettleman wrote: To All the Great Folks in 300 Land. Apparently the cam that we installed during the C engine rebuild is a bit lumpy as compared to the stock cam. Have what I would call a momentary stutter when the right foot presses down. We adjusted carb linkage so instead of running on 2 barrels it's now on 4, which has improved performance, but still get the occasional hiccup. Mechanic said we need to swap out the jets for larger size and that will solve problem. Figure someone else has had this problem and would appreciate your help with this issue. --
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