Worn out throttle shaft bushings => high idle?
August 7th, 2012, 05:29 PM
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Worn out throttle shaft bushings => high idle?
I have a '72 Quadrajet on my '66 330 and I'm not able to get the idle speed down to 800 rpm even with the idle adjusting screw screwed out completely.
I have already done all the common stuff like timing checked, vacuum lines replaced...
Then I read that it's a well known issue, that the thottle shaft bushings wear out and vacuum leaks are the consequence.
So I went out to the car and just pulled the thottle lever to the front of the engine and the stronger I pulled, the lower it idled!
Is this the symptom of worn out throttle shaft bushings?
Would you rather replace them or get a totally remanufactured carb instead?
Thanks!
I have already done all the common stuff like timing checked, vacuum lines replaced...
Then I read that it's a well known issue, that the thottle shaft bushings wear out and vacuum leaks are the consequence.
So I went out to the car and just pulled the thottle lever to the front of the engine and the stronger I pulled, the lower it idled!
Is this the symptom of worn out throttle shaft bushings?
Would you rather replace them or get a totally remanufactured carb instead?
Thanks!
August 8th, 2012, 08:39 AM
#3
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Before you take it off and chunk it, I have a couple of questions? Are you running manifold or ported vacuum to your distributor advance? Disconnect the throttle linkage and see if it's holding it back?
Spray some carb cleaner around the throttle shaft and see if your idle changes.
Spray some carb cleaner around the throttle shaft and see if your idle changes.
August 8th, 2012, 09:41 AM
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i'm assuming you have the throttle actuated by the rod setup that is stock on a '66. that rod has an adjustable length. i'm curious as to how you connected the throttle rod to that '72 carb, pix would be great.
bill
bill
August 8th, 2012, 12:08 PM
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Before you take it off and chunk it, I have a couple of questions? Are you running manifold or ported vacuum to your distributor advance? Disconnect the throttle linkage and see if it's holding it back?
Spray some carb cleaner around the throttle shaft and see if your idle changes.
Spray some carb cleaner around the throttle shaft and see if your idle changes.
I have already disconnected the throttle linkage, but the idle speed has not changed!
I'll try that as soon as I'm at home again!
August 8th, 2012, 12:11 PM
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I think the former owner has just drilled a hole in the throttle lever...
August 8th, 2012, 12:15 PM
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Just thought about buying an Autoline remanufactured carburetor, fitting for my 330? Is this a good idea?
August 8th, 2012, 10:04 PM
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just a thought... instead of carb. cleaner, use ether starting fluid to spray around the throttle shafts. the ether won't clean out the buildup around worn throttle shaft bores. by using carb. cleaner, you risk cleaning the buildup from the throttle shaft bores and making the problem worse. sometimes gunk is good.
as far as the curb idle speed adjustment you're using, it's on the driver's side of the carb; right?(just making sure)
bill
as far as the curb idle speed adjustment you're using, it's on the driver's side of the carb; right?(just making sure)
bill
August 9th, 2012, 01:03 AM
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Yes, the choke is operated by a cable, and I'm sure I didn't set it. I've checked it with the air cleaner taken off, as well!I did that when I set my timing! Didn't make a difference though
All the unused vacuum ports are plugged, all the lines are new, just like the carburetor gaskets.
Are there any other possible sources for a vacuum leak besides the bushings?
August 9th, 2012, 01:10 AM
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just a thought... instead of carb. cleaner, use ether starting fluid to spray around the throttle shafts. the ether won't clean out the buildup around worn throttle shaft bores. by using carb. cleaner, you risk cleaning the buildup from the throttle shaft bores and making the problem worse. sometimes gunk is good.
as far as the curb idle speed adjustment you're using, it's on the driver's side of the carb; right?(just making sure)
bill
as far as the curb idle speed adjustment you're using, it's on the driver's side of the carb; right?(just making sure)
bill
Yes it is
August 9th, 2012, 05:11 AM
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Are you sure the butterflies are closing all the way? I don't know what the throttle linkage looks like on your's but if it was my 68 with the Holley I'd say it was a weak return spring
August 9th, 2012, 10:09 AM
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bill
August 9th, 2012, 10:13 AM
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August 9th, 2012, 11:16 AM
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Okay today I sprayed some starting fluid around the throttle shaft and the idle seemed to get a little rough for a short time...
I attached a pic of how the stock rod setup is connected to the carb!
I attached a pic of how the stock rod setup is connected to the carb!
August 9th, 2012, 12:18 PM
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It really does not matter how it's hooked as long as it does not bind and allow full movement of the throttle. I've seen some very creative throttle linkages over the years. You may have some worn bushings, you hava a carb shop over there?
August 9th, 2012, 02:32 PM
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I just posted it because Bill was curious about how it was connected
None that is specialized in American carbs, they mostly do Italian and German one's...So I think I'd buy one in the US and get it shipped, maybe cheaper as well.
Do you know a good carb builder at reasonable prices or are the ones on Rockauto any good?
None that is specialized in American carbs, they mostly do Italian and German one's...So I think I'd buy one in the US and get it shipped, maybe cheaper as well.
Do you know a good carb builder at reasonable prices or are the ones on Rockauto any good?
August 9th, 2012, 03:39 PM
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Ok, so your choke linkage is not hanging up, and not stuck on hi idle. With your throttle linkage disconnected, you still can't get the idle adjusted lower with the screw, and you have no vacuum leaks other than the bushings. Also your vacuum advance you said was connected to ported vacuum, no vacuum at idle.
We've also determined that your mechanical nor your vacuum advance is not sticking. SO the problem must be in the carb. Correct?
We've also determined that your mechanical nor your vacuum advance is not sticking. SO the problem must be in the carb. Correct?
August 9th, 2012, 03:49 PM
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Ok, so your choke linkage is not hanging up, and not stuck on hi idle. With your throttle linkage disconnected, you still can't get the idle adjusted lower with the screw, and you have no vacuum leaks other than the bushings. Also your vacuum advance you said was connected to ported vacuum, no vacuum at idle.
We've also determined that your mechanical nor your vacuum advance is not sticking. SO the problem must be in the carb. Correct?
We've also determined that your mechanical nor your vacuum advance is not sticking. SO the problem must be in the carb. Correct?
August 9th, 2012, 04:58 PM
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That's the question...as you might already have noticed I'm neither an expert in carbs nor in anything else
But I will likely stay with the q-jet, because I read mostly good things about them and it will be fun to irritate all the germans, who think that everything without a big EDELBROCK on it is bad and worthless
Don't know if I should get a 70 or later model to use the existing choke mechanism, or maybe the 66 model is the best for this engine?!
I also don't know where to get it from...the best deals seem to be the Autoline remanufactured carbs on rockauto, but there sure are some better ones around.
If I wasn't on a tight budget, I would just search someone to build me one, that would still work fine with some possible future upgrades!
Thanks for taking your time and answering all my questions I really appreciate it!
But I will likely stay with the q-jet, because I read mostly good things about them and it will be fun to irritate all the germans, who think that everything without a big EDELBROCK on it is bad and worthless
Don't know if I should get a 70 or later model to use the existing choke mechanism, or maybe the 66 model is the best for this engine?!
I also don't know where to get it from...the best deals seem to be the Autoline remanufactured carbs on rockauto, but there sure are some better ones around.
If I wasn't on a tight budget, I would just search someone to build me one, that would still work fine with some possible future upgrades!
Thanks for taking your time and answering all my questions I really appreciate it!
August 9th, 2012, 08:57 PM
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August 9th, 2012, 09:16 PM
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bill
August 10th, 2012, 06:31 AM
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August 10th, 2012, 07:59 AM
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well, yeah it kind of does matter. if your geometry and throw are wrong, you'll cause excessive wear on the throttle shaft bore. you may also cause excessive force on the end of the throttle shaft, which could cause it to break off, then you have a real problem as in this application there is nothing to close the throttle. you can also make the car a real pita to drive.
bill
bill
Originally Posted by oldcutlass
It really does not matter how it's hooked as long as it does not bind and allow full movement of the throttle...
August 10th, 2012, 08:39 AM
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August 21st, 2012, 01:24 PM
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August 21st, 2012, 01:54 PM
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Dan, did you also use the 72 q-jet intake? Did your 66 originally have a q-jet? I would rebuild the q-jet before I bought a generic carb. I have head of some guys who have had no problems and others who were totally unappy. Obviously, being in Germany comlicates things I have alwaysused www.cliffshighperformance.com for everyhing Quadrajet. Although he specializes in Pontiac, he can rebuild or ell grea rebuild kits wih parts that don't leak, no matter what kind of fuel or additives you have. He usually answers the phone, and might be able to help figure out what is wrong.
August 21st, 2012, 02:19 PM
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Dan, did you also use the 72 q-jet intake? Did your 66 originally have a q-jet? I would rebuild the q-jet before I bought a generic carb. I have head of some guys who have had no problems and others who were totally unappy. Obviously, being in Germany comlicates things I have alwaysused www.cliffshighperformance.com for everyhing Quadrajet. Although he specializes in Pontiac, he can rebuild or ell grea rebuild kits wih parts that don't leak, no matter what kind of fuel or additives you have. He usually answers the phone, and might be able to help figure out what is wrong.
I definately want to keep the q-jet and cliffs seems to be a good source of information and for parts! Thank you for the recommendation
I'll send him an e-mail, as well! I don't have enough time to think about how to express what I mean on the phone
Thanks again!
August 21st, 2012, 04:22 PM
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Seems like you haven't read my letter of appreciation in the radiator thread yet
It works just great many thanks again
August 21st, 2012, 06:26 PM
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