In gear idle dropped

[junkpile]

While driving my 69 charger with a 440 the other day, it was idling and cruising fine all day. After a faster start from a stop sign, nothing that even turned over tires. I got to the next stop sign in the car idle down from its usual idle point I usually idle at about 900 RPM when sitting still in gear, and it dropped to 500 and to about 200 and then back to 500 but it will not come back up. It’s as if somebody took the idle screw and turned it all the way down but in park it idles fine put the car in gear it idles back down and wants to quit Any idea of where I can look. The only thing I’ve changed on the car was I added a new coil? Other than that it’s been running fine

 

[DanielSlocum]

ive seen several vacuum port plugs split open and/or fall apart lately causing vacuum leaks on multiple vehicles. probably more china junk!

 

[WileERobby]

First check linkage and all vacuum lines.

 

[junkpile]

everything with the carb linkage was and has been right on for months with no change. The only thing i changed was the coil. The Distributor is a Firecore from Mancini Racing about 2 yrs old (light use on the car) That has been the only distributor I have had in years that has spot on timing. If the vacuum advance bladder tore I would have to replace the distributor. I tried a test capping off the vacuume to the advance and carb and i remember it ran the same (bad), so if that is the case it would mean the the advance on the distributor is shot and replacing it would bring the idle back up to where it should be. Am i correct in saying that.

 

[twecomm]

Recently had an idle problem on my 383 w/ Edelbrock 4 Bbl carb. w/727 automatic. All of a sudden it started idling all over the place in RPM's. At first, thought something mechanical changed with idle setting or other carb linkage. Re-adjusted idle set screw a few times but idle kept changing every time I drove it. So ,did some searching and found an Edelbrock video that recommended backing out and removing both the idle mixture adjust screws and blow compressed air thru the idle adjust screw holes, as this would blow out any deposits that may have contaminated the idle circuit.
Did as recommended with compressed air, re-installed idle screws to 1-1/2 turns from fully seated, and that worked ! So did a fine tune on idle mixture and a final setting of idle RPM's. Idles perfectly now, stable RPM's.. In neutral 920 RPM's in gear it's 500 RPM's.

 

[junkpile]

I will try to blow out the carb. the carb is only 1 1/2 old and I have had no issues. i did have a high pitch whistle when I was looking over the car the other day, it only made the sound when in gear at idle. But it went away after a short run time and has not been back. car still runs lousy and rpm is way off of normal setting. 1100 in park idle, 900 in gear idle cam is 484/284 this is the best idle for driving around in atlanta traffic.

 

[440beep]

The new coil you added, is it the same exact as what was replaced? If not, might it have a different ohm resistance and that’s causing the issues?

 

[junkpile]

new coil is different. went from a stock replacement to a an Accell superstock for a hotter spark.

 

[Geoff 2]

Depending on the electrical specs, your Accel coil may NOT be producing a hotter spark.
We need a lot more info on the ign system, carb type etc.
The idle rpms are probably about right for the 484 cam. It will want a LOT of idle timing [ probably 30-40* ] for best idle. This then affects the carb idle & off idle cct. Until this is corrected, the engine/carb will never run as well as it should.

The quote below about idle timing. It is in a carb book, not an ign book. Hmm. Food for thought....why is that? And why is timing mentioned multiple times in a carb book????

 

[junkpile]

o.k. I found the problem. The Vacuum advance on the distributor is not holding vacuum. I am using a Firecore from Mancini racing, and its timing has been spot on with no isues. They do not seem to sell just the advance for the distributor (has a smaller head than a stock one). I dont have the budget for a new distributor right now but would like to run the car this fall to some events. Can I cap the advance and carb ports and just adjust the idle manually to the set points (900 idle in gear, 1100 idle in park) I had before and drive the car that way or will it be an issue? base timing is 12 with 36 total.

 

[Geoff 2]

I don't know why I bother sometimes......
Did you read what I posted in post #9?????????????
12* at idle isn't going to cut it.
IT IS NEVER GOING TO RUN AS WELL AS IT COULD UNTIL IT HAS MORE TIMING AT IDLE.

 

[Geoff 2]

And this.....

 

[Geoff 2]

And this....

 

[Geoff 2]

And this.....

 

[junkpile]

I appreciate the articles, i just cant read them on the thread, and saving them they come out too blurry to read. so I appoligise fro not reading them. As for my issue i have ad 12 degrees base timing with 36 all in for years without any issues, even drove this thing from Atlanta GA to Lake George NY for the Adirondack Nationals, thats 1200 miles one way, without an issue or problem. So doubt my timing set up is the issue. I was saying that after a cruise night driving home the idle in drive just dropped out to half of its RPMs at at stop sign. it will not recover. I did find the vacuum advance is not holding vacuum (issue #1), after disconnecting the advance and running a race set up i once did long ago ( carb idle adjustment to run without vacuum advance) the car still would not idle in gear properly but will idle in Park and Neutral. I am going to try a new distributor as soon as it comes in, but I am willing to listen to other ideas.

thanks

 

[Geoff 2]

Sorry about the blurriness. It is ok on my computer, readable, but uploading onto websites, it loses some clarity.

Any ideas, I am pretty hopeless with computers?

 

[junkpile]

I have no clue but I have tried to save them to a different email. ill let you know if it works.

 

[71Beeper]

Geoff 2, if you can scan the article as a Adobe .pdf file then attach the file in a post, it will be clearer to read.

 

[Geoff 2]

Thanks. Will get the son-in-law on the job!

 

[pedal2themetal]

Hi,
a whistle is usually a vacuum leak gasket or such.. Actually idle should be like 650 to 750 .. 900 is high unless its highly modified big cam.. 1 1/2 turns on the mixture screws is just to get it running and should be adjusted with a vacuum gauge to highest vacuum at idle.

good luck take care be safe
tim