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Discussion Starter · #1 ·
Ok, my 84' 350 idles very rough when cold and responds horrible to any quick acceleration. When you first start the truck you litterally have to hold it open at half throttle for a good 5 minutes or else it will just die when you let it idle, but it idles just fine when warm. If you mash the pedal to the floor from idle, the engine just kinda chokes for a second but picks up a moment later. It's got the origional Rochester carb.

I personally think it's simply the mixture screws need adjusting, but my pops swears up and down that the Rochesters didn't have mixture screws. Also he says that at the front of the carb, just infront of the throttle linkage, is an electric actuator that holds the engine at higher throttle based on the temp. This sounds like total BS to me, considering that the thing he calls the actuator it just a bolt that threads out. Any verification on this?

I don't quite have the choke hooked up yet, but I don't think that would cause the bad idle since the choke is suppose to open completely once the engine has actually started.

So if anyone has any thoughts, please let me know. It's a pain to sit there with the throttle half open just to keep the thing running.
 

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I would hook up the choke first of all. The choke can affect the motor runs when it is cold and until it is at full operating temp. You can adjust the mixture on Rochesters (at least on the older ones (pre 1980s)...not sure on something that new...so, I really do not want to give bad advise there.

Other things that can affect idle and throttle response are:
Poorly adjusted or not connected choke,
Out of time (adjust timing)
Mixture
Vacuum leak

Unfortunately...mixture and timing and vacuum all work hand in hand...so if you make adjustments to one, it is best to check all settings...but honestly, hook your choke up.

Slight adjustments to the carb mixture are sometimes needed during climate changes (winter/summer etc).

This is just from my experience.
 

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Discussion Starter · #3 ·
OK, well I got some more info. Now that the thing's actually running. :thumbup:

Anyhow, I've got the classis problem of a rough idle until it warms up. As I posted before, if I don't hold it down to 1/2 throttle, it just sputters and dies. I wired the choke up and it works just like it should. Stays closed for the first 2-3mins the engine is running, then opens up.

The thing still idles like crap though, and if you just mash the gas, it sputters for a second but revs up like you'd expect. So I'm wondering, what other stuff can I check? The timing's perfect, the choke works, and all vacume lines are sealed. I thought about the mixture screws, but according to my pops this QJet is sealed so you can't reach the mixture screws. He also swears up and down that there's a high-idle acuator that keeps the engine idleing real high when it's cold. :confused:
 
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