Author Topic: Car will not idle unless the choke plate is closed a bit  (Read 2570 times)

Offline kevmore

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Car will not idle unless the choke plate is closed a bit
« on: September 30, 2016, 08:49:08 PM »
The car: 1980 Olds cutlass calais 442 W30.
350 ci Carb number: 17080260  0300 DHP
When we got the car it seemed to kind of run ok.  It sat for a winter outside, and in the summer we tried to get it to run.  It would start but would not idle.  Had to be on the throttle about 3000 rpm to keep it running.  Once you let go of the throttle it would die.  I took the carb off and tore it down.  It was full of white slimy gunk.  The outside two tubes were laying in the bottom of the carb, and it was a real mess.   I noticed that the needle was installed with the clip in the holes of the float arm, not on the front edge like it is supposed to be.  One of the mixture screws was almost all the way in, and the other was almost all the way out.  I tapped the tubes in with the back of a screw driver and couldn't pull them back out.  I assumed all the jets and rods were the stock items, and didn't take note of the sizes.  The car seemed to run real rich so I lowered the float level a bit.  Also, the top gasket had a big square chunk missing that went around the primary rods.  Once I saw all this wrong I was certain it would run great after the carb kit.  The only part of the kit I couldn't find a home for was a triangle gasket.  I looked high and low for a place to put it but didn't find out where it went.  After the rebuild, the car started and ran much better, but it will still not idle.  I started with the mixture screws at 4 turns out, but it does not matter where I put them it still runs like crap.  If I close off the choke a little bit it runs nice and smooth but at about 1500 rpm.  It revs up real nice but dies when left to idle.  This tells me I am running lean because it needs the choke.  If I crank up the idle it runs, but them I'm off the idle circuit and the mixture screws don't seem to do anything.  I can just about close them right off, or turn them all the way out and not much change.  I read on here something about air bleed screws under a triangle shaped cover, but can't find it.  Does anybody have a picture? 
Does the float level affect the idle circuit?  I am by no means an expert on Q-Jets, but do have some experience.  I have several pictures from the rebuild if anybody wants to see them. 
If it's got tits or tires it's gonna give you trouble!!

Offline Marx3

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Re: Car will not idle unless the choke plate is closed a bit
« Reply #1 on: October 01, 2016, 11:01:54 AM »
float level has very little to do with the idle circuit. It ain't a Holley  :) )
It sounds like you did not pull the idle tubes ?

Offline kevmore

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Re: Car will not idle unless the choke plate is closed a bit
« Reply #2 on: October 02, 2016, 12:43:41 AM »
Thanks for taking the time to read and reply Marx3. 

No I didn't pull the idle tubes, but I blew air through them. 

After looking at a lot of pictures I think I have found the idle tubes.  Those are the ones I have to thread a screw into and pull out?  They sit flush with the air horn gasket surface?  The ones that stick out about 2 inches are the main well air bleed tubes, and the secondary accelerating well tubes correct?  (Two of those were loose in the float bowl, Those are the ones I tapped back in). 

A large vacuum leak would cause a similar situation would it not?  It idles real smooth if the choke plate is manually closed a bit with a finger, but it idles quite high when I do that.

The carb kit I got from Bumper to Bumper only consisted of a pump cup and spring, and needle and seat, and a bunch of gaskets.

Thanks again.
If it's got tits or tires it's gonna give you trouble!!

Offline Marx3

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Re: Car will not idle unless the choke plate is closed a bit
« Reply #3 on: October 02, 2016, 10:40:20 AM »
Yes, your description sounds like the idle tubes. Just dont mistake them for the down channel restrictions.... ( they are sitting right in front of the idle tubes )

A big vacum leak will certainly cause the engine to not idle.
If I were you I would get Cliff on the horn and order a quality kit ( 45$ ). These kits include everything.
You may also want to get a new set of primary metering rods. Most carbs from those years were ridiculously lean on calibration. You might be cheating yourself out of a noticable increase in torque.

Offline kevmore

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Re: Car will not idle unless the choke plate is closed a bit
« Reply #4 on: October 03, 2016, 10:11:23 PM »
Yep, you nailed that one Marx3.  Took the carb off again and the idle tubes were plugged solid.  Thanks to your help and the help of others that have tutorials online on how to remove and replace the tubes.  I just tapped the tubes with a punch and cut off a screw and used that to pop the whole thing out.  I didn't drill out to a different size, I just cleaned it up and used my drill press and a punch to press them back together.  Then tapped them into the casting holes.  Worked like  charm. 

So now I should be able to set the mixture screws and it will actually make a difference.  Once I get the idle down the ported vacuum should not be present at idle.  That is probably why it idled so fast cause I had to turn the idle up to make it run, and it was getting ported vacuum causing even more rpm. 

I eventually want to purchase Cliffs book on Q-Jets, but with the exchange rate for Canada, and shipping it is almost $50 Canadian, and I just lost my job so I can't afford it right now, but it sounds really awesome.  I couldn't even purchase the carb adjusting tool at any local parts places, I had to order it from the states.

Thanks again, you saved my over $500 bucks, that is how much a rebuilt carb costs here.
If it's got tits or tires it's gonna give you trouble!!

Offline kevmore

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Re: Car will not idle unless the choke plate is closed a bit
« Reply #5 on: October 04, 2016, 08:49:32 PM »
Put the carb on today and got it running real nice.  Thanks again for the help Marx3.
If it's got tits or tires it's gonna give you trouble!!