The $20 mystery Q-Jet

airboatgreg

airboatgreg

Royal Smart Person
Oct 2, 2016
1,173
1,105
113
#41
I have drilled a lot of carbs on mostly stock engines and used what we called jewelers drills. Really small. I also have read that a tapered ream is better than a drill. Might be cutting hairs. I also would be specific to the area that was lean. Idle, pump, power, main and secondary circuits. This takes you to know the carb and what and where each individual circuit is. Of course, take all other factors out such as vacuum leaks, ignition and mechanical issues. I still have the drill bits and reams:)
 
pontiacgp

pontiacgp

Canadian Prime Minister
Mar 31, 2006
23,799
8,892
113
Kitchener, Ontario
#42
I have drilled a lot of carbs on mostly stock engines and used what we called jewelers drills. Really small. I also have read that a tapered ream is better than a drill. Might be cutting hairs. I also would be specific to the area that was lean. Idle, pump, power, main and secondary circuits. This takes you to know the carb and what and where each individual circuit is. Of course, take all other factors out such as vacuum leaks, ignition and mechanical issues. I still have the drill bits and reams:)
Taper reamer is a nice idea but how would you set the depth. We use to use tape to set the depth for taper reamers but tape would be hard to use to open the idle port
 
Bonnewagon

Bonnewagon

Geezer
Sep 18, 2009
5,632
1,624
113
Queens, NY
#43
Hi Donovan. I didn't know your name but we've posted back and forth before. I know very few first names on here unless it's in their avatar or something. I'm guilty of not including that too- I'll fix that. Yes, I have Cliff's book as well as Doug's and I have found that most Q-jet problems are solved with a good cleaning and checking it against specs. It is only when I get an orphan carb or build something GM never intended and need a one-off that I begin modifying. For example if the carb acts too small then it probably needs bigger jets since they affect the air/fuel ratio all across the rpm range. But if you get an off-idle stumble then you would try a different metering rod since that only affects off-idle to mid-rpm. WOT problems are where the secondary rods need attention. Over the years I have found that knowing what NOT to do is the most important thing. There are way too many car mag articles advising dumb procedures that get guys in trouble. Pagrunt did the right thing. He took an unknown carb and showed us what he had then asked for advice. You can't help wanting to help him out because you know he will appreciate it.
 
Rktpwrd

Rktpwrd

Royal Smart Person
Feb 2, 2015
1,788
5,296
113
Calgary, Alberta, Canada
#44
Hi Donovan. I didn't know your name but we've posted back and forth before. I know very few first names on here unless it's in their avatar or something. I'm guilty of not including that too- I'll fix that. Yes, I have Cliff's book as well as Doug's and I have found that most Q-jet problems are solved with a good cleaning and checking it against specs. It is only when I get an orphan carb or build something GM never intended and need a one-off that I begin modifying. For example if the carb acts too small then it probably needs bigger jets since they affect the air/fuel ratio all across the rpm range. But if you get an off-idle stumble then you would try a different metering rod since that only affects off-idle to mid-rpm. WOT problems are where the secondary rods need attention. Over the years I have found that knowing what NOT to do is the most important thing. There are way too many car mag articles advising dumb procedures that get guys in trouble. Pagrunt did the right thing. He took an unknown carb and showed us what he had then asked for advice. You can't help wanting to help him out because you know he will appreciate it.
No worries sir, I know we’ve talked on here the odd time before, but haven’t really gotten to “know” one another so to speak. Pleasure to make your formal acquaintance!

Trying to get my QJ to work on my engine was something that definitely fell into the “GM never intended” category, so that’s why the modifications I made ended up being as extensive as they were. Cliff’s recommendations and specs were spot on the money tho, that man definitely knows his way around those carbs.

Hopefully Pagrunt will find motivation and confidence in tackling the rebuild on his from positive experiences like mine, armed with the RIGHT info, it’s not only possible, but fairly easy to accomplish.

D.
 
pagrunt

pagrunt

Comic Book Super Hero
Sep 14, 2014
2,782
2,936
113
Shelocta, Pa
#45
There are way too many car mag articles advising dumb procedures that get guys in trouble. Pagrunt did the right thing. He took an unknown carb and showed us what he had then asked for advice. You can't help wanting to help him out because you know he will appreciate it.
And when I open it up I'll be posting more pics with questions. I really do appreciate the help from everyone on this.
 

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