Rebuildman- what book are you using to look up the original factory calibration specs by carb number?

I've worked on/raced scillions of QJets but never really gave a rat's backside what the stock calibration was since I set them up the way I wanted them anyway, regardless of what was in them originally. I'd love to have the info, through.

Can't disagree with anything you've said so far. I will add that if you take 2 different QJets and set them up with identical jets/rods/idle passage restrictions they will perform just about identically 95% of the time. That's handy since you can always start with the same "baseline" setup and tweak in small increments from there. There IS a lot of stuff to know about them, but once you understand it all (like you obviously do) you can quickly get an idea of where a "sane" calibration is at for them.

Usually something like this works well on most performance-oriented 350-400ci engines:

Primary jets: 76-78
Primary rods: 44-46 (K style if it's integral choke, B style if divorced choke)
Power piston spring: Somewhere around 6" opening point, depending on typical manifold vacuum levels
Idle orifice tube: .038
Idle channel restriction: .054-.059 kinda range
Idle air bleed: I forget, I'm typing this from memory. .049" or thereabouts?
Idle discharge ports: open 'em up to about .090"
Secondary rods: DR (middle of the road) or DA (richer than DR everywhere)
Secondary hanger: G
Air valve tension spring: ~1/2 turn from the zero tension point.
Choke pull off restriction: if accessible, drill it out with pin drills until it takes about 3/4 second to fully extend. ~.015-.020"

Then there's those rare few QJets (the other 5%) that just want EVERYTHING to be different. But no ghost stories today!

Thanks in advance for the info.

 

wow, this thread has become a plethora of information ! I'm definately bookmarking this!

Yea, Rebuildman, where was that info found? a book? something I can get my hands on? a website?

Damon, I don't know anything about any of the lines you started with "idle"....
I'm going to have to take apart my q-jet again and take some pictures and try and figure out where those are.... I'm guessing when you say "open it up", you're talking about using a drill press and that exact sized drill bit? (only logical way I can think of...)

Rather then coaxing you to explain each of those (channel restriction, discharge ports, orifice tube etc.), since that would probably induce carpal tunnel syndrom... is there a source of info about this? I've heard of "Rochestors carburetors" by Doug Roe.... is this a good one? explains those idle modifications? either way, i'd like to learn about those things...
Thank you all -J

 

In those sizes you'd be doing it by hand with a pin vise.

 

When I actually rebuilt these things afew years ago I called Rochester (Delco-Remy) and asked for the overhaul books, they sent them to me free of charge! And I got free updates, until carbs were no longer being used.
But there are three large volumes, a stack about 1 foot tall. Anyway, it lists all the Q Jets by year and application, gives all the part numbers and picture breakdowns of each one. Also has all the set up spec sheets, like the ones you get in the carb kits, plus a section on how to rebuild and the 'factory fixes" for problems encountered thru the years. Including the electronic models. Very helpful.

The book by Doe Roe is the best for modifications and basic rebuilding, there are two printings that I know of, a later one with a mostly black front cover and a early one that is sorta green, if you can, get them both because they have different info.
The later one you will be able to purchase new but the older old will have to be found at swap meets or used book store.

When I was rebuilding them I actually would take measurements of all the factory calibrations and write down a spec sheet for each carb because the books don't give that info, so I have a pretty good idea what each engine size needed or used stock.
I haven't really done a whole lot with these lately because I moved on to TPI, but I still have a large pile of parts and cores.

 

Here is more food for thought: Some of you may already know this. Q-Jets were made with two different size primary venturies, it has been published that they were 750 and 800 cfm, I have never flow benched one but people who have say that is close. I have found the bigger ones on engines you would never expect them to be on and they were correct per the Rochester book.
Also, the book does not tell you what size the carb is, so unless you know a good part number, or how to tell the difference betwen the 750 and 800 you don't know where to look for these.

Here is another:
With the airhorn removed, normally you see 4 brass tubes hanging down, two air bleeds, two fuel supply for secondaries, ever see one with six tubes? Four of the tubes are for fuel supply to the secondaries! Anyone drag racing with one of these should show some interest in that!

I also had a Q-Jet that was factory correct for a Ford Cobra Jet, what engine was that I forget, 429? A GM carb on a Ford!! From the factory! That just goes to show it could really work on the big motors! The inside of that carb was really different.

O.K., enough from me.

Keep those minds working!

 

Why not? Mopars used Q-jets too.

 

Try College budget, buddy..

 

Alright, FINALLY had the time & money to go get a carb, now that I have fixed the body from that accident. I got one from a mid-80's buick. It looks more of less the same. I think all the vacuum ports are right, etc. But the secondary jets look a tad different, to my untrained eyes. The number off it is

17080284
3519 cw4

And it's got a tag on it from autoline or something, probably from a past rebuild. How does this sound? Something I cna work with?

Also, based on my engine and driving habits (daily driven) and stuff, what jets/metering rods/whatever should I get?

Thanks.

 

No such thing as secondary jets.
Primary jet + rods
Secondary rods and hangers

A past rebuild is a mixed blessing, *** knows what's in the carb or if they've botched it... Personally I would have found one that was so covered in crud that no one has touched it in 20 years. Soak that in cleaner for a few days and it's good as new, whereas if some hick has drilled that one to crap....

I have no idea what those #'s are, maybe someone else can look it up, regardless, if that car had a 305 (most likely), it was an LG4 and would be setup more or less like yours.

Check what the hanger and secondary rods are, that's easy, and gives you a tad bit of info. Other then that you can start rebuilding it to find out the primary rods and jets.



side note: Buddy is trading me wheels with tires for my wheels with tires, so I no longer need to get tires exchanged (if you knew the deal I was getting you'd be camped out at PAP looking for knight rider wheels...) oh yea, if you need some secondary rods or hangers, or a float or whatever, let me know, I have a collection... oh, and I just built a carb stand for rebuilding...

 

Sure there are, they're just not replaceable.

 

Hmm, well I can always take it back if it looks fuxx0red. The tag suggests it was rebuilt by someone who knows what they are doing.. I was actually looking for one sorta clean because then the linkages and stuff.. I dont know. I probably will need new rods, thanks.

Heh at least I know it's been rebilt. Could been done without my knowing. hmm...

 

bah, Aperion, always correcting.... To you Ryan, it's like there are no jets, since you can't do anything with them....

Yea, it was rebuilt by someone competent i'll bet... maybe more tuned for that car however, if that's bad or not.... Also they may have rebuilt it in the '80s, when perhaps the style was to swap in a different power piston spring to open it at a lower vacuum rating, giving even better economy for that 'ol buick.... And since you don't get power piston springs in a normal rebuild kit, you're stuck with that one.... Well, that's a long shot, but you get the idea... Years of grease and goop clean up real nice in a tub of carb cleaner...

You don't really have any REAL mods in your car however, I don't think you need different rods/jets than normal LG-4 ones, otherwise you'll just kill your mileage, but by all means try others, but when you find out what makes the car run the best and such, you may just be surprised you're back where you started.

Good luck. If you get into the rebuild and get stuck, maybe start a new thread, this one is big...

 

yeah, probably will start a new thread. Maybe I should just return it, if I can find a better one. But my problem was that I couldnt find many with the side fuel inlet, and the ones I could find were missing parts... I trust there's a way to identify a new piston or whathaveyou..

edit: oh, and as far as REAL mods, I'll have headers soon..? lol

 

yea, a lot have that weird mixture contol looking solenoid plug on top (double accelerator pump or something).... or front fuel inlet...
well, give it a shot, if it doesn't work after a rebuild you can always gut it, then return the shell and exchange...

 

Yeah. Long as there's a way to make sure the power piston springs are the ones I want, etc..

 

The easiest thing to do is not worry about it and just replace whatever's in there with the parts you want.

 

yea, it's not a big deal either way, perhaps I made it out to sound worse than it could be... I was just saying, you don't know what someone else did to the carb, and be wary.

But yea, Mopac has those replaceable parts on the shelf generally, (edelbrock stuff), or can tire can special order them for you, if you can't get to Mopac during their banking style hours...

 

Ok, yeah, I was all worried, considering taking it back.. but oh well. I need to at elast open it up first. So I need.. carb cleaner, rebuild kit, time.

Mopac sucks. Really dont like that place. Plus, my buddy works for a dealership so I can get stuff for cost + 10%.

 

It's pretty much only the Calgary Mopac that sucks, mostly because of the people. The other locations aren't so bad. Fortunately Calgary has a decent selection of speed shops. Certainly better than Salmon Arm, at least. :P

 

lucky sob.
A dealership eh? ooooh, good for you. I asked a dealership about quadrajet parts, and they looked at me like I was looking for parts for my horse and buggy or something... If it's not younger than 5 years old to a dealership, it's ancient history....

You'll also need:

-Torx T8, T15, T20 (nab a nutdriver kit from C-tire for $5)
-a stand is nice to have, I made mine with 4x 4"x5/16" bolts and 4x nuts, and a 10"x10" square of 3/4" plywood (had it lying around)
-you probably already have a wrench to get your fuel inlet off, crescent wrench works
- can of compressed air
- a way to get out the roll pin, I used a bent 3/32" dia nail (#6 or something...), about 3/4" long, bent 90*, along with some wire cutters.... your rebuild kit will likely have a new one, but...
- or you can use a 3/32" punch
-containers. lots of them. Old tuna cans are good, get some masking tape, put a part in them with the screws, and label the can.
-lots of light
-probably other things that are normal to have, pliers, hammer, stuff like that....

If you're doing this alone, with the help of the internet (here), you're in for one fun time.... a good long time... I highly recommend someone who has rebuilt one before to help, but if you like learning yourself, then experience is the best teacher.
Budget 2-3 re-rebuilds before it works right, I had more like 6, but there were extenuating circumstances (cc ->non-cc)

 

haha, salmon arm... geez, what do you DO there? I lived in the okanagan, and I mean salmon arm??? Try and fish in the cheesy man made "pond"? Rent a houseboat? then... not much... Do you work for Mascon by any chance? as a software engg?
At least in BC you have Lordco... boy, the Vernon Lordco was a total godsend...

 

You're going to the wrong dealership then.

 

I sold all my stock options right at the peak of the dot com hype, and now I've retired to a nice quiet small town where I can sit and count all my money while I listen to my cars rust.

I wish.

I develop automated inspection and grading systems for the forestry sector.

 

ah, the Riverside base there. Good union pay. But boy, a boring town for sure...

 

haha yeah I havent had much luck with some dealerships, but like Aperion said, you're going to the wrong one. My friend can get his dealership to order just about anything. He got stereo equipment there.

Uh, 2-3 re-rebuilds? *gulp*

 

I don't work for Riverside, I work for a manufacturer that serves the forestry companies. We're not a union shop, or at least us engineers aren't, only the fabricators in the other building. I'd get paid less if I joined them. As for the town, no it's not real exciting, but how much excitement do you need? The older you get the less you care about such things.

 

Ok. I have finally had a chance to crack this damn thing open, now that exams are finally over and I have a morning off work. I made another thread about a few questions I have about the kit I got, here: https://www.thirdgen.org/techbb2/sho...hreadid=306075

 

Rebuildman, how about this #17059226, whats it off of?

 

I think it's off a '79 chev with an auto. But that's kinda useless without the engine size.. (I found a decoder in an article Sonix sent me)

 

I found a number that was close "17056226" The difference being the fifth didget is a 6 instead of a 9 (76 vs. 79). The listing said it was for a 1976 L82 350.

So is my 17059226 for a 1979 L82? I have no clue.

 

Who cares?


Rebuild it and make your own, forget about what it was on 30 years ago.

 

Good point. Always nice to know what stock jets it has though. As well as the updated choke, etc..

What listing is this?

 

The jets/rods aren't indicated by the exterior #, or else i'd be saving a lot of time tearing apart q-jets in the wreckers...

The updated choke is pretty obvious by looking at it, one has an electrical connection..... The old one - does not.


If it really bothers you, PM or email rebuildman, as you can see by his posts/date registered, he's not a terribly active member.

 

Oh, nono, I just meant you can get a ballpark... Like if it's for a 305 or 350...

 

Sorry, I am old.

I like history.

 

This was my point.

If it really did come from an L82, then I could look at the cam specs (I already did, they are part #3896962, 312* adv. 222* @ .050 I.450 lift E.460 lift) and determine if it would be close to what I wanted to run (since I can't read the #'s on the jets).

But, Sonix is right too, jets are cheap, and I think I will start out with 74 jets, and 50M rods, and the DR secondary rods on the L hanger and maybe move up to a B hanger if needed. Then it will be set up like the Edelbrock performance carb #1910. I want to call Edlebrock up tomorrow and ask them what size the air bleeds are and drill mine to that size for a baseline start.

If I remember correctly Edelbrock claims this carb is good for a hydraulic cam up to 228* @ .050. My mechanical cam may be in this ballpark and if not, then the air bleeds can be drilled in .001 increments.