what should the idle revs be?, mine sits at around 1300/1400 rpm, is that normal? seems abit high to me

cheers

dave

 

Dave, you want to be looking at around 800rpm in N and 600ish in D.

 

ok, so how do i get it to run at a lower idle, is there a screw on the carb somewhere?

 

Yes there is a screw that you can adjust to change the idle speed.

First make sure the choke mechanism is working correctly, it may be that it is stuck on the fast idle cam which would cause a high idle. If this is all free, make sure the throttle blades are completely closed.

Then you can adjust the idle speed....

If you read the sticky about timing etc, you will see how to adjust the idle mixture screws ( not curb idle speed ) to get best vacuum reading.
According to Lars, most carb problems are timing related.

Good luck, will see if I can dig out a picture of the curb idle screw for you.

 

here's a pic of the choke opening, is that far enough open?





is there ment to be a wire going into cabin to pull the choke on?

 

If that engine is cold, the choke is way to far open. It should look like it is almost closed.

There isn't a wire that goes into the cabin from the choke. The screw you need to adjust is somewhere on the mechanism that works the choke. Can't tell from your pix - you should be able to find it...

Good luck

 

Mine idles at 1400 in Neutral and drops to 700 in Drive. Everything seems to be fine. Starts with just a key bump, Carb is rebuilt, and vacuum is great!! I do have a very lopey cam which I think has something to do with it.....

 

Kronus,
Looks like BUBBA took a keen interest in your car before you got it.
Buy some books and start reading, and good luck.
Just remember "It's only nuts and bolts"
Later,

 

lol, u are your right there, some fools have been playing with it!, car came from somewhere in mississippi, its only been in the uk for 6 months

thanks info guys

dave

 

Dave, what are the numbers on that carb? Looks like an older Qjet with a divorced style choke. Pretty sure yours should have an integrated mechanism.
Numbers should be on the side of the main body.. starting 70.....

 

damn. that doesn't sound right at all imo..

 

Idle should be about 750-800 with manual tranny, 700 with an automatic in drive.

 

It is 700 in drive. Its just that in Park, it is around 1400. I have no idea why, but all I know is that it starts and runs perfect!! The only bitch is that I usually have to shut it off in drive or I get a hell of a backfire out of my sidepipes!!!!

 

Before I took the end play out of my distributor by shimming the shaft, my idle was 1100 in park and 650 in drive. Once I shimmed the shaft, it dropped to 850 in park, 650 in drive. It's not that difficult a project, and the distributor shims are at any parts store.

 

You have one seriously messed up system there. The carb is not the right carb for your application, (I assume this is a 1975 or newer car..?) and several linkage pieces are disconnected and/or missing. Your choke is completely non functional, and it's not fully open. That means that your idle speed is being controlled by the fast idle cam, your fuel mixtures are screwed up, and your secondaries are locked out. Additionally, your distributor is installed incorrectly, so I'll bet your timing is also significantly off... If I were you, I'd start by setting up the distributor and timing right. Then, fix up that carb as much as you can while you look for the right carb and choke system for your car.

The other thing you really need to do: You do not have a PCV installed or hooked up. Your tranny modulator line is attached to the PCV port on the carb. Get the PCV system installed and hooked up and fix that modulator routing. A properly functioning PCV will help you idle better, provide better ring seal, and it will lower your oil consumption.

 

Very interesting! Never heard about this before. I have checked everything else out, namely the vacuum, and carb. But this never came up. A couple of questions:

1. How can i tell if it needs shims?

2. How the heck do you do it??


Thanks!

 

Two things you should do:

1) a current and archive thread search of C3 using "distributor shims" as the key words, and
2) email Lars for his paper on rebuilding a distributor. (He provides an excellent step-by-step how-to. Plus, it might already be in one of the archived threads.)

You basically pull the distributor, check the amount of end play, remove the end gear, shim to specs, reassemble/reinstall distributor and re-time your engine. Even if you stop to check the rest of the distributor and clean things up as you go along, you can finish this project in an hour to an hour and a half easily.

 

Thanks Blue!! Sounds like next weekends project!!

 

Hi, its a 78 vette, so why is this carb wrong?

wots wrong with the dizzy?

wots pcv?

cheers

dave

 

1975 and later Vettes use an integral choke carb. Pre-75 use divorced choke carbs. Your carb is a divorced choke carb, which means that the entire choke system is missing and cannot be made to operate on your car. You need a complete integral choke carb along with the hot air choke tubes to make the choke function. I can't tell from the photo resolution if you have the correct intake manifold with the hot air tube provisions.

The distrubutor, when correctly installed, should be "square" in the engine compartment. In other words, the wire terminal on the driver's side should be 90-degrees straight out on the driver's side, and the square coil on top of the dizzy should be square in the engine compartment. The forward driver's side wire tower is the #1 wire tower, and on yours it's going over to the passenger side of the engine (#1 is on the driver's side). The distributor is simply installed incorrectly.

PCV is positive crankcase ventilation. It pulls a negative pressure on the crankcase when the engine is running. Upon close exam of your photo, it looks like the PCV may be installed in the rear of the driver's side valve cover and plumbed into that nasty-looking pipe fitting on the back of your manifold - at first it looked like it was just the power brake line going to that "tree." You may be okay on the PCV, but I would yank that pipe system out of the manifold and run your lines correctly for better performance of the brake and PCV systems.

If you want to fix that thing up, we can start scrounging up all the parts you need and then send you everything as a "Care Package." Let me know if you need help with this. It just takes time and money.