Hey guys,
Having a lil bit of an issue with my motor. As some of you will remember, its about a year old this time of year, very few street miles on it(couple miles a day on avg so probably around 1000) There has been NO WORK done to it lately, I havent had the time to tinker with it, let alone really have the time to fix it right now. My moms been driving it lately, so it hasn't been abused too badly.

Anyway, the other day my mom came to me... motors idling at ~2000-3000 rpms off and on. Thought maybe the electric choke might be screwy so I disconnected it and saw no improvement. Also tried backing off the idle screw, car died. It really doesn't like to idle much less than 1,000 rpms when its running fine anyway due to the cam size. So what all else can I check that might be the culprit for this?
The return spring is in place, the distributer is still tight, the linkage doesn't appear bent or anything out of the ordinary, I'm out of ideas.

Thanks in Advance!

Since you've already checked the carb linkage,I would check for a broken vacuum line or one that has pulled loose this will cause it to idle faster.

Originally posted by JRS70LS5:
Since you've already checked the carb linkage,I would check for a broken vacuum line or one that has pulled loose this will cause it to idle faster. My thoughts exactly, definitely sounds like a vacuum leak. Don't forget to rule out the base gasket too!
Best of Luck!!

Thanks for the replies guys!
Its funny you guys both leaned towards a vacuum leak as I almost asked if that would cause it in the initial question but didnt want to sound like an idiot, haha.

Vacuum advance is locked out in the distributer, I'm not running a PCV, and I don't have power brakes so off the top of my head I don't think there are any vacuum lines running, so its probably a good assumption that its the baseplate or intake. Baseplate I can deal with, intake I just plain don't have the time for right now. But I guess it can't be too big of a leak since its not running horribly right? (throttle response etc is still good)
Oh well, any more ideas are welcomed, I'll check for leaks tomorrow when its light!
I'll keep ya'll posted!

Check the float levels! graemlins/beers.gif

Try a different return spring

The first thing I thought was the centrifugal advance springs are too loose or fallen off.

if it is a vaccum leak, it would run lean. not a good thing.

eddie

Alright guys,
I sprayed carb cleaner around the carb baseplate and all around the intake sealing surfaces, the idle didn't lower or smooth out any and stayed at around 2000 rpms. Tried a different return spring, fired it up, idled at 2000 rpms. Float levels are good. Cant check the centrifugal advance springs because I dont know where they are in the distributer :confused:
Any more ideas or help with where the springs are would be appreciated!
thanks

The springs are easy to find in the distributor ... pop off the cap and rotor, you should see them, they are small ones, there should be two, one on either side.

Is there a vacuum line running down to the transmission for the vacuum modulator? Possible leak there.

Check the secondaries,sounds like they made be stuck partly open.What carb is on it?If it's a Holley with vacuum secondaries,the check ball in the vacuum pod may be dirty,or the throttle shafts may be loose,causing the plates to hang up. Steve

On second thought,I have to agree with a vacuum leak.If you backed off the idle screw,the engine would still run on the secondaries.But with a large vacuum leak,when you back off the primary idle,it covers the idle transfer slots,effectively cutting off the fuel supply.If you have access to a loaner carb,I'd give that a try.It could be an internal vacuum leak in the carb,but it would have to be pretty big.Timing will only raise the idle so far without more throttle opening,so I don't think that's the problem. Steve

Not sure what carb you have, but my Edelbrock with electric choke did that occasionally. Then I ran a new hot wire from the wiper motor and the problem went away (The Edelbrocks draw more power than a rochester or holley).
Disconnecting the electric choke did nothing on mine either (since it was essentailly disconnected to start with). But, hooking it up correctly did fix it.

What kind of distributor?

Sorry guys that I havent gotten back, I got fed up with it yesterday and was ready to send it to a shop. But, alas I just pulled it in the driveway and figured I'd get it figured out when I got the time and the stress levels go down after graduation in a couple weeks.

So thanks for the replies thus far. To fill in a little more on the combo of stuff. The carbeurator is a Holley 3310 750cfm vacuum secondaries, added the electric choke afterwards because this motor is very "cold blooded" and my mom has been daily driving the malibu lately while I've been in school.(I havent had the time to drive it after school either so this way it gets its legs stretched still)

Distributer is a standard HEI, has a cap adapt on it with an external MSD blaster II coil on the firewall. Brass rotor and cap.. vacuum advance is locked out.

Hope that helps, any other questions of what it might have ask away!
Thanks for all the ideas thus far!

From your signature it looks like you have an automatic trans. If so, is there a vacuum line going to the modulator on the trans?

Originally posted by stroobydoo:
From your signature it looks like you have an automatic trans. If so, is there a vacuum line going to the modulator on the trans? Uhh, I already asked that.

Whoops, forgot to touch on that yesterday. Yes there is a vacuum modulator line running. Its hard line up just past the distributer and a short about 6" piece to the carb. I inspected that yesterday and found no cracks and the rubber was still supple. I didnt have any extra line to replace it with to rule it out completely. However it doesnt "appear" to be bad.