Idle issues

[junkpile]

440, .030 over, 484/284 cam, Edelbrock 750 carb. Base timing 12degrees with 36 total, using firecore distributor and mopar electronic ignition. 727 trans 2800 stall converter. Car has always ran at 1100 rpm in park and 900 in drive, I have two distributors both have checked out and are in perfect condition.

I want to start by saying this car has been running perfectly with no issues for several years now. Recently while driving I came to a stop and idle rpm just dropped out. It usually idles in gear at 900rpm and suddenly dropped to 350-400 rpm and wants to stall out. This has never happened before and I would like y to be pointed to possible problems. In my garage if I put it in gear I can hear a whistle sound, I changed the carburetor base gasket and I still get the whistle and low rpm but only in gear.

Any help pointing me in the right direction is appreciated. Please note there have been no issues with this set up for years, that’s why I’m seeking advice because I’m am stumped.

 

[Fran Blacker]

If idle is high in neutral vacuum leak. Power brake booster clapped out.

 

[Scott Engelhardt]

Does it still idle at 1100 in park? Does it idle smooth in park? You can check for vacuum leak with carb spray.

 

[Geoff 2]

Not sure about the whistle, check PCV is operating properly. Rough running could be flooding.

Remove carb top to check for worn needles & seats, fuel logged float, float level adj [ Should be 7/16" ]. Clogged fuel filter may let debris may let debris get into n&s.
No gasket needed if you are careful.

 

[junkpile]

The car is running and starts easily. The idle when in park is at 1000 rpm (100rpm lower than before) but the idle is smooth, only when put in gear does it drop to 400rpm. The power brake booster is off a separate vacuum pump system and has no connection to the motor. The pvc valve is working as it should. I have replced the carburator gasket thinking that was the issue. I can not find a vacuum leak when idling, but i do here a loud whine/whistle when dropped in gear. I dont have anyone to hold the car in gear to try to find where this is coming from. this is a 69 charger and the only thing i have not done is disconnect the vacuum headlight line and cap it off (still used manifold vacuum). My fuel filter appears to be clean no dirt seen in it, although it does need to be changed.

 

[junkpile]

I have a short video but I cant seem to download it. Anyone know how to add a video?

 

[junkpile]

I can not load a video. sorry. I will say one other thing if this get people thinking. I did try disconnecting the vacuum advance and re timed the car and idle and as soon as it was put in drive the RPMs dropped to 350. Really need help with this, or the car will be sidelined and put on jackstand for the foreseeable future.

 

[71Beeper]

A whistle at idle usually is a lean idle mixture if not a vacuum leak.
Turn the mixture screws out half a turn to see if it makes a difference.

 

[Triplegreen500]

I agree. Wiggle test all your vacuum lines at idle. If that doesn't do anything, spray them all with brakleen. If the idle changes...you found it.

 

[junkpile]

I will as soon as I can get a helper. the whistle is only when the car is idling in gear. not in park.

could the fuel pump not be keeping up when the car is in gear? I can rev it smoothing to 3000 rpm in park and neutral, under load its completely different. since this happened when driving home from a cruise night, its hard to see the mixture changing, but its running slightly rich at idle in park now.

 

[Just Send It]

Without physically being there to hear it, it sounds like a lean idle mixture. Id start by richening your primary mixture screws a 1/4 turn and see what happens. If you have a vacuum gauge, I'd check that too to see if the needle starts bouncing. If it's bouncing, that's indicative there's a leak.

Also, do you have a fuel pressure gauge? If yes, what PSI is it?

 

[Triplegreen500]

The load on the engine changes when you put it in gear, along with the RPM and the vacuum level. If you have a vacuum leak, it does not matter "in gear" or "in park" - wiggle the lines, and if one is leaking, the wiggle will expose it regardless of gear position. Putting it in gear could change things just enough that it will "wiggle" itself into the leak position.

 

[Detective D]

Torque converter?
Does it act the same in park and neutral, and only bog in gear? Should not have fluid pressure in park, but will fill the converter in neutral. Do you accelerate smoothly once you start moving?
Check the fluid level in neutral just because it is easy
Could be a lot of things but if everything runs like a top otherwise and only is affected by the transmission change, can't rule out the transmission.

 

[BigCheez]

Most likely either one of the idle mixture ports got blocked or it has a vacuum leak. Take out each mixture and spray carb cleaner in the hole with the straw the use a blow gun and blow compressed air in , put the mixture screws back in ant see if anything changed. Then to find a vacuum leak you need to disconnect each vacuum line and block it off, a smoke machine would find it in under 1 minute.

 

[Geoff 2]

You need to find the cause of the whistle. There can be two causes, one of which is harmless. External to the carb & internal [ inside the carb ]. This sounds more like it is coming from inside the carb & some carbs/combinations get a whistle at certain rpms [ harmless ]. The reason the whistle changes in/out of gear is because of the change in air speed. Nothing to do with leanness.

Post #7. 350 rpm drop after re-timing. Big red flag. That cam will need a LOT more timing than 12* init. I suspect that you had more than 12* & then after you re-timed it to 12*, it now has this big rpm drop. Try this simple test: while idling, slowly turn the dist CW. Rpm will increase.

 

[twecomm]

This may be a similar post to what Bigcheez posted just above. I posted my experiences below in early August.

"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. "

 

[Fran Blacker]

Edelbrork carb that came with a choke. Somebody removed the choke and didn't plug the hole or lost the seal??

 

[Budnicks]

Edelbrock Carb (1407-750) I'd start there,
any number of things or passages could be clogged
especially if it sits a lot (crappy gas/additives etc)
something clogged in the carb or an orifice somewhere
maybe idle circut,
maybe metering rods have fuel additive crap built up on them
(white **** or glaze/shellac sticky **** from old fuel)

maybe a bad hose/multiple hoses, bad vacuum hose,
bad PCV
maybe an internal fuel leak or an internal vacuum leak (whistle)
possible vacuum leak too (whistle) like said above could be harmless
BUT;
a lot of times a whistle it's a vacuum leak, or lean, more time than not a leak
or really bad tune, clogged orifices
I'd 1st check all hoses & vac. port caps

filthy air filter ?

1st off
I'd run/put more advance in initial timing, than 12*s too

go back & do the basics, does it have
cap good ?
rotor good ?
good plugs ?
good wires ?
& not just new plugs/wires/rotor cap etc. 10-15 years ago
you assume is still good, years later when you 1st built it

bad resistance in any of that
old plug wires are culprits a lot
or something wrong in the distr./ignition system
if it has points check them, burnt ? &/or a failed or failing condenser
if it has electronic ignition check the air gap,
it needs to be like 0.010"

weak/poor resistance will wreak havoc

The coil take a **** ?
seen new coils that were junk now too
check for cracks or oil leaking from it too
it will seem like a fuel issue

any orange dust in the dist. cap ?
(means cross-firing or arching)
did you recently wash the engine ? or spray it
(get water in the cap)

fuel pump or fuel pump push rod
&/or fuel filter took a ****,
or the sock on the sending unit clogged with sediment rust etc.
happen now more than you think,
lots of nasty **** in fuel now