Need Fresh Idea's! Fixed!

[Explorer]

Patience is wearing thin. 66 Mustang, automatic, Autolite 1100 1v. As far as I know the only thing non-stock is the Petronics point replacement only. It will only idle about 1400-1500 rpm with the manual choke half way closed. My feeble mind keeps telling me vacuum leak and drawing air from somewhere else and closing choke is making up the diff. Disconnected and plugged vacuum port to dizzy and auto tranny. Sprayed everything down with carb cleaner and no leaks anywhere. Did change plugs, cap, rotor and new PCV but needed them anyway. Nothing I have done has affected it at all. Idle mix screw has no effect, but I guess it wouldn't at that rpm. Any suggestions?

 

[Asa]

fouled up timing can change the idle speed
have you messed with any of the linkages on the carb? some of those can stick or a rod could have been tweaked which can adjust the idle

what have you done before this? is there another thread?

 

[Explorer]

No other thread, I have repaired the PO jerry rigged setup on throttle linkage, but don't believe thats it. It's not the fact that it won't idle down, it just won't run unless the choke is pulled which raises the rpm due to the cam on throttle. I can back the idle adjustment all the way off, control throttle manually but still won't run unless choke is half closed. Sorry, sometimes I have a hard time making things clear enough to understand.

 

[Asa]

it's cool, just remember that the more info you can give the higher the quality of help you'll get

and i'm afraid i've spent my load to be much more help, i've been working for too long with computerized vehicles and not on classics, i could suggest that you change your throttle position sensor, but i doubt that would help


something about your situation feels familiar though, have you tried starting it with the choke all the way open, but the pedal halfway down?
also, once the engine has warmed up, are you able to open the choke to get it to idle down?

 

[Explorer]

First problem is I don't have a clue about a SCV system. Went back out and adjusted the idle down to within reason, but still can't open the choke even at full operating temp. Acts like it's just way to lean to run and is getting air somewhere else. I can do a Duraspark in my my sleep and thats in my plans with a direct mount 2v, but I'm just not ready to do it yet. Need to get this running as is so I can take to tranny shop and put a few miles on this engine checking it out. I'll pull the head and stuff this winter. Hope to have it finished by spring for young son to drive. Never ran into a vehicle that would only run with the choke closed.

 

[Asa]

well, here's some info about the SCV system, maybe it'll help?
viewtopic.php?t=18841

 

[rbohm]

8) the first thing i usually recommend that people do in your situation is to replace the gasket under the carb adapter. there are two there, one between the carb and the adapter and one between the adapter and the intake. the carb one always gets replaced, the other usually never does.

 

[early ford fan]

i ve seen one barrels that have vacumn ports on the bottom that require a gasket with a notch in it.

 

[Explorer]

8) the first thing i usually recommend that people do in your situation is to replace the gasket under the carb adapter. there are two there, one between the carb and the adapter and one between the adapter and the intake. the carb one always gets replaced, the other usually never does.

I'll do that in the morning. You're right, no excuse for not doing it while I had the carb off. Thats why I sprayed the carb cleaner. I'll eliminate that possibility.
early ford fan: No ports in carb base on this one.

 

[JackFish]

To what is the base timing set at that rpm? Can you rev it up or does it die?
I saw "pertronix points" and went hmmm...

I have a fully modified head, etc. and found it hard to get the idle down.
I drilled a hole in the throttle butterfly. Low end throttle response is great now, and it's idling about 1000rpm in neutral and thumping between 750 and 800 in gear with the brake on.

 

[SteveS]

I really don't know the SVC system but isn't there a vacuum line to the distributor? If you plug that you'd eliminate a possible vacuum leak there.

 

[ludwig]

it just won't run unless the choke is pulled which raises the rpm due to the cam on throttle. I can back the idle adjustment all the way off, control throttle manually but still won't run unless choke is half closed.

That means that you are getting too much air unless you cut the air flow in half with the choke butterfly. Look for major vacuum leak somewhere.

 

[Explorer]

To what is the base timing set at that rpm? Can you rev it up or does it die?
I saw "pertronix points" and went hmmm...

I have a fully modified head, etc. and found it hard to get the idle down.
I drilled a hole in the throttle butterfly. Low end throttle response is great now, and it's idling about 1000rpm in neutral and thumping between 750 and 800 in gear with the brake on.

Points only replaced with petronics dizzy module by PO. She'll rev fine, no bogging etc. Haven't even tried a light on it yet. I bought this project not running, as usual, finished up the Bronco so just starting on this.

 

[JackFish]

Oh so this is a stock engine.

 

[Lazy JW]

....... Haven't even tried a light on it yet.....

Extremely important to have that correct; don't waste any more time chasing vacuum leaks until you KNOW the base timing is where it belongs.

 

[Asa]

....... Haven't even tried a light on it yet.....

Extremely important to have that correct; don't waste any more time chasing vacuum leaks until you KNOW the base timing is where it belongs.

with the engine revving like that, would the mechanical advance get involved, throwing the light off?

 

[Explorer]

ASA: Going to read up on the SCV in the morning
Lazy JW: Since I got the idle down, I'll put the light on it in the morning after I change the spacer gasket.
I'll pull a couple plugs and see if it's still burning lean like the old ones indicated. I work entirely by myself so it was almost a necessity to get it to run long enough for me to check everything. At least I reached that point today.

 

[Explorer]

Ok, what's next? Replaced the gasket under spacer. Got it to idle about 900rpm(got a slight miss, maybe plug wire) with distributor vacuum disconnected and plugged at carb. Timing is 12 degrees BTDC. Any lower doesn't want to run. Actually idles reasonable, but the choke is still nearly closed. Idle mix screw is 1.5 turns out.

 

[JackFish]

Balancer slipped?

 

[Explorer]

Not saying that it isn't, but don't really see how that would effect my problem with the choke. To add to the mix even further, checked manifold vacuum and pulling 17 hg. That's all my new engine pulls. I'm leaning toward something FUBAR with the carb. I put a rebuild kit in it and cleaned everything. New SCV etc, only thing I didn't pull was the power valve which the instructions didn't cover. It's running exactly the same as before I rebuilt it.