Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Heavier throttle (mostly) issues
tayto:
you need to completely rebuild the carb correctly. this includes installing most if not all of the parts supplied in the kit. check trouble areas leaking well plugs, worn throttle shafts, stripped threads, binding linkage etc etc. you also need to setup the carb as it came from factory, setting float height is critical. i told you how correctly hook the needle clip yet you didnt fix it and ran it anyway? did you read the mercruiser bulletin i posted? cliff's book is not a "how to" rebuild step by step it discusses theory and how to modify the carb. there will be a sheet that was sent with your kit, you can look up your carb number and it will tell you the float height. if you spend a few hours reading or searching on this forum you will find most of the answers and methods that are needed to successfully rebuild & modify these carbs. there are also a ton of youtube videos on rebuilding as well.
as far as a vacuum leak from the carb did you check to see if the airhorn or main body was warped? over torquing the mounting bolts will cause warping. also i the idle tubes are in a blind hole, i am not too sure how you were able to see the wire sticking out of the other end. i push wire in until it bottoms, mark the wire then check the other side, if they go in the same distance there is a good chance they are not plugged.
MP81:
--- Quote from: tayto on September 14, 2019, 06:08:18 PM ---i told you how correctly hook the needle clip yet you didnt fix it and ran it anyway?
--- End quote ---
By the time you sent that, the carb was already rebuilt and on the car, so...
What sheet was sent with my rebuild kit? I did not receive any kind of sheet, aside from the link to this, which I always had up on my computer to reference: https://cliffshighperformance.com/wp-content/uploads/2018/10/1981-up-ccc.pdf
The book is pretty step by step, but I don't recall any thing related to setting float height, aside from it being just over the top of the casting surface, which it was. Was the same as the one in there before.
There are four holes right there. Two bottom out, two go through the bottom of the carb. Everything was clean.
I torqued the mounting bolts to the 12 lb-ft specified in the service manual, so those are to spec. But it definitely sounds like that's where the big leak is, as moving my hand near there "blocks" the sound.
Didn't check to see if the air horn or casting were warped, but the gasket interface seemed pretty consistent.
Kenth:
You need to set the float correctly and hang in the inlet needle clip from behind of the float arm, no way around this.
If not, you will never get the carb working properly.
Follow the instructions for a basic rebuild in order, step by step:
https://cliffshighperformance.com/wp-content/uploads/2018/10/1981-up-ccc.pdf
https://cliffshighperformance.com/simplemachinesforum/index.php?action=dlattach;topic=4148.0;attach=1383;image
MP81:
It looks like the clip could bind and cause the needle to stick open - but with both that, and a float that is maybe too high, wouldn't it overflow the carb with gas, and not just run slightly rich? Or can it cause rich running without overflowing the carb?
If I'm able to re-use the same gaskets and take it apart again, then I'm not opposed to doing that. Removing it from the car isn't exactly difficult, nor is getting the air horn off (the TPS plunger is a bit of a bitch, though).
That PDF doesn't really make it clear how to accurately adjust the float. Should it be 3/16" below the top of the main casting or 3/16" above the top of the main casting? The book stated the float should come above the main casting.
Is it worthwhile to get the Quadrajet float gauge to do this, or is it easy enough to do with a straightedge and calipers?
Kenth:
A too high float setting and binding inlet needle due to misplaced clip can and WILL make the engine run rich without flooding, but flooding does occur from time to time.
A new gasket can be reused many times on the same carb.
The procedure is described on page 2 figure #3 and the fuel level settings are in adjustment data tables on pages 3, 5 and 6.
What is the application number on your Q-jet?
https://cliffshighperformance.com/wp-content/uploads/2018/10/1981-up-ccc.pdf
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