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#1 |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Runability issue. Minor. Question.
I have a 1981 454 engine that was rebuilt with bigger cam/ different heads and i had the stock quadrajet rebuilt.
Issue im having is that it doesnt always idle. Some days it idles perfect all day. Other days, it idles fine at first then stops. I have to keep my foot on the gas. Any thoughts???? Everything is hooked up fine. Why would some days it idle, then others it not??
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New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#2 |
Registered User
![]() Join Date: May 2011
Location: Hendersonville, nc
Posts: 85
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Re: Runability issue. Minor. Question.
Sounds like the choke is getting hung up. Check for vaccum leaks and to see if the linkage is rubbing on anything.
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71 c20, 350/automatic 71 K5 Blazer, 350 3 speed (really my 16 yr old sons)http://67-72chevytrucks.com/vboard/s...d.php?t=686111 71 GMC build thread; http://67-72chevytrucks.com/vboard/s...d.php?t=468765 47 Chevy Aerosedan, 403 Olds/350 turbo 69 Camaro, 307/powerglide 06 Silverado Z71 |
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#3 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,626
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Re: Runability issue. Minor. Question.
Primary throttle shaft is loose. Plates move sideways slightly and hang up on throttle bore. Changes your idle. I had one do the same. One of the little screws that holds the plate to the shaft was loose. Plate moved slightly.
Stroke the throttle by hand wide open and see if you can move the shaft side to side. |
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#4 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
As for the throttle shaft, where is that located exactly? So open the throttle all the way, and then rock it back and forth to check for play? I took the carb to a carb guy here in kirkland and right in front of me he tore the whole thing down, and put it all back together. Didnt mention anyhing about the shaft being lose. He put two small ball bearings into this two tiny holes and hammered them in. It idled fine for about ten mins then started to act up...
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New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#5 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,626
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Re: Runability issue. Minor. Question.
Well that makes it easy. A no brainer. Take it back to the guy who rebuilt it.
I don't know where he might hammer 2 small bearings into. Primary throttle shaft is in the bottom plate of the carb. When you stroke the throttle it has the 2 primary plates attached to it. The plates can be seen if you look down into the carb when you stroke the throttle. Below the choke plate. If the shaft moves side to side the plates can hang up in the bore changing the idle rpm. Can you take a pic of your carb pointing to where he put the bearings in. Here's a pic of a carb that shows the bottom side. The round plates attach to a shaft which runs from side to side. The round plates can hang up sometimes. In the pic the top 2 are the primary. Bottom 2 are the secondaries. This isn't a quadrajet but looks similiar. http://67-72chevytrucks.com/vboard/s...d.php?t=489059 Last edited by geezer#99; 10-16-2011 at 03:37 PM. |
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#6 |
dazed and confused
Join Date: Jul 2008
Location: marion nc
Posts: 1,649
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Re: Runability issue. Minor. Question.
mine was getting to much pressure. i had to put a regulator on it .
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members met: redbaron69, billsbowtie,nc67 |
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#7 | |
Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: Runability issue. Minor. Question.
Quote:
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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#8 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
Yes, it does. it does the rop rop rop die... If i dont put gas to it. Geez, the carb was in really good shape when i took it off the factory engine. basically cleaned it up. Then put it on the truck. Well, i was getting that idle issue so i took it to a carb place. He took it apart and plugged these two holes on either side of the carb. I wish i knew wht they were called. lol. Sorry.
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New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#9 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,626
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Re: Runability issue. Minor. Question.
You can't reach inside. When you open the throttle just wiggle that part around to check for excess play. Up, down, sideto side. The throttle arm on the drivers side that the return spring is attached too is what you need to move around.
You don't need to know what the holes are called. We just wonder where they were located. Top or bottom. Inside, outside?? |
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#10 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
Ok, i wiggled that and it feels REALLY solid. BUT, i had the return spring still hooked up.. i will try that again. As for the holes. He took the whole carb apart and they were at the bottom. Says its very common and he does it to every quadrajet. It was INSIDE the carb near the front or the back. HOles were evenly spaced. This guy owns carb connection in kirkland. He basically pulled the carb off, took it all apart, shook everything down, checked everything for play, popped two bb's in those two holes and put it back together. But, it still did the same thing. If i cant find any play or vacuum leaks (he couldnt find a vacuum leak either) then i will take it back i guess. I am running a pcv if that matters at all??? I will get some pics of the carb and post em.
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New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#11 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,626
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Re: Runability issue. Minor. Question.
Very little side to side movement can make it hang up. Where's your return spring hooked to? The spring could be pulling it sideways.
I checked your build thread. Spring to the back. Try hooking it up so it pulls straight forward. Spring in front. Hooked to the back like yours might not be pulling it shut consistently. Last edited by geezer#99; 10-17-2011 at 10:34 AM. |
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#12 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
Just to recheck, when checking for vacuum leak, get some carb spray, and with the vehicle running, you spray it around the base of the carb and if you get any idle pickup there is a leak somewhere.. The carb guy did that once before and nothing, but im willing to recheck. ahah...
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New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#13 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
Click this pic for video. ![]() ![]() ![]() ![]() ![]() ![]()
__________________
New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#14 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,626
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Re: Runability issue. Minor. Question.
Geez Man!!! You take awesome pics!!!
The movement side to side would be enough to hang up the plates in the bore. Up, down is minimal. Shaft bushings appear good. The pic with the writing on it is your secondary lock out. THat movement might effect your changing idle but I suspect it's the side to side of the primary that's your problem. WE'll try the front first. I'd move your return spring around so it's pulling from the front. Hook one end into that hole just below the cable hookup. You could make a temporary bracket that can be bolted down to one of your intake or valve cover bolts. A tall L-shaped bracket would work. Set it up to pull straight ahead. If that cures it you can get some nicer brackets on Summit. Once we get that figured out we're gonna get you too replace that piece of rubber fuel line with a new complete steel tubing line. That rubber line is a big fire waiting to happen. |
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#15 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
That fuel line was supposed to be temporary... Putting it on my fix list now.
__________________
New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#16 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,626
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Re: Runability issue. Minor. Question.
Try it in front first.
Next fix could be pulling carb off, flipping it over, modifying the plate or limiting side to side movement. All the things you might not be familiar with. The ones I fixed by just moving the spring helped. If you need to talk it over pm your number. |
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#17 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
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New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#18 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
|
Re: Runability issue. Minor. Question.
Quote:
So that throttle you were talking about is good. Changed all that stuff you said and its good to go. here is the situation. Start the truck up and it runs ok when its cold. As it warms up it runs fine but it just does not want to idle. BUTTTTT, pay attention to this part. If the truck is fully warm, and when i pull up to a light and i let it DIE by itself, then restart it, the issue doesnt come back. WTF!!! Also, the damn thing when you start it cold, just doesnt start well at all. I think there is something messed up with the choke. I might get rid of the electric and go manual or something. So what do you think. Why when its fully warm not want to idle. But the first time you let it die by itself. Then restart, it idles great for however long you want it to???? Thoughts?
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New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#19 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
|
Re: Runability issue. Minor. Question.
Quote:
Well, i figured out one issue. So as i was staring at the carb, and the truck was idling. I covered with my hand the little top choke butterfly, and the rpms smoothed out and the engine rpm increase. I have a vacuum leak in this engine somewhere. So, i picked up a propane bottle and am going to go find the leak. Let you know once i have this figured. Think its weird the carb guy would miss somehting so obvious.
__________________
New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#20 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,626
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Re: Runability issue. Minor. Question.
So when you closed off the choke butterfly was the motor warmed up or still working on the choke.
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#21 |
One of the First
![]() Join Date: Jan 2000
Location: St. Augustine,FL.
Posts: 4,054
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Re: Runability issue. Minor. Question.
You could have a slight lean condition in the main jets - might not big enough. The main jets control the amount fuel that is pulled through the idle circuit. You can tell if it is lean by adjusting the idle mixture screws. If you don't get a noticeable response then its lean. Don't get the main jets confused with the metering rods - the metering rods control flow for cruise and response. I went through the same issue (all the above troubleshooting) and finally upped the size of the main jets in the Q-Jet carb and it runs fine. Took alot of reserch and reading but, I gained alot of base knowledge.
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DAVID PASSMORE ST AUGUSTINE ,FL ZIP 32084 '71 SWB K/10 CUSTOM DELUXE (Chili) '72 BLAZER K/5 Muscle Truck (Mule) '72 LWB K/20 CHEYENNE (Blackie) |
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#22 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
Yes, it was fully warmed up when i coverd that area and idle smoothed out and raised up quite a bit.
__________________
New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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#23 |
Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,626
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Re: Runability issue. Minor. Question.
OK!!
Along the lines of D. Passmore's post. Maybe your metering rods are hanging up on the gasket. Runs lean cause they're stuck down in the jets. Here's a link on quads. Lots of info. http://www.digitalcorvettes.com/foru...ad.php?t=88376 |
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#24 |
One of the First
![]() Join Date: Jan 2000
Location: St. Augustine,FL.
Posts: 4,054
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Re: Runability issue. Minor. Question.
Try this link too.
http://www.florida4x4.com/tech/quadrajet/index.php Another indication was when you used your hand to cover the "area" and it smooth out is a maybe a tell sign that you need more fuel in the idle circuit. |
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#25 | |
PITbut
Join Date: Sep 2007
Location: monroe washington
Posts: 3,052
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Re: Runability issue. Minor. Question.
Quote:
The other issue i have is that my damn choke isnt working correctly. Its not going on the high cam idle. Truck wont start for crap cold. I get out and manually open the throttle and flip the choke lever all the way up and then get in and she fires right off but as soon as i touch the gas pedal idle drops down.
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New project. 1971 Twin Turbo blazer http://67-72chevytrucks.com/vboard/s...d.php?t=676047 My new YOUTUBE channel.. Videos of my truck and a current walk around. Lyrikz74 Youtube channel DONE! SOLD! ![]() My 1971 stepside build thread My Build Thread UPDATED 6/11. DONE and sold. |
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