Which Quadrajet Should I use?

I have 3 quadrajets, dont know which one to build; 17087124, 17085001, 17058213. The 17087124 is super clean, looks like it was rebuilt not long before it came off of its vehicle, but I think it needs throttle shaft bushings. Running a near 400hp 350, which one is best?

 

That sounds like a carb king question.

 

Go with the easiets one to rebuild as long as it has the mixture screws to adjust. Otherwise its a smog carb and for get it all together...

 

I agree w Porknbeaner. peace

 

If you have a good one they are great,but I have never had any luck rebuilding them. HRP

 

Those are all 1978 "Smog Carburetors"
I'd look for an older one one that starts without the 1 in front of the 70*
http://www.ehow.com/how_6130381_decode-rochester-quadrajet-carburetor-numbers.html
http://www.recarbco.com/technical/rochester/qjet.html
(I'm running one off a '69 Z28 with some secondary metering rods from an Eldorado on a 262" SBC Haven't touched it since I put it together in 2000 either.)

 

A Q-jet from a '69 Z-28? Boy, THATS a rare piece...

 

Yeah. It must be from a 'one off,'
rarer-than-rare, 'ultra-top-secret'
factory experimental prototype
that was never released to the
public. You see them advertised
on epay all the time.

Mart3406
=====================

 

Must be Canadian.

 

Cliff Ruggles has a good qjet book out. He also sells parts and offers throttle shaft rebushing. He's got a web site at cliffshighperformance. I've had to call him directly a time or two. He gives advice over the phone and is decent to deal with. In his book he has a number of standard builds according to what carb you're starting with and what it's going on. Basically, you can start with just about any qjet, it's all in what you do with it. You may plug this passage and redrill it smaller, then enlarge this one. It's in the book. Read it several times, take it to the bathroom with you and really learn what all the parts do.

 

I'd forget about all of them and look for one in the '69-74 vintage to rebuild.

 

I have a "love hate" relationship with the q-jet, I'd build the one with the least slop around the throttle shaft.

 

FWIW, the way early, say, like my '67 350 SS/RS Camaro cars Q-Jet had a rubber "condum" that fit over the float needle to hold it in place that flowed more than the later Q-Jets did.

And the REAL trick setting up a Q-Jet is to tune the back top air butterfly's to kick in when you want them to.

You set them by loosening the little bitty hex set screw that is on the, (I want to say, bottom), of the pass side of the top shaft. BUT you have to hold the shaft using a little bitty straight screw driver that is inserted into the slot on the end of the butterfly's shaft because of the balance spring!!

Turn the screw driver NO MORE than an 1/8 of a turn in or out for starters. Then cinch the hex set screw down and take her out and run her to see how that back air valves kick in. You don't like it, then come back and repeat until you like the way that the butterfly's kick in.

I set mine so that i could sneak up on 65 to 70 mph on the front barrels, but when I floored it, the back barrels would kick in at 30 to 35 mph and I was off!!

I, to this day, remember the loud suck when my secondaries kicked in at rpm.

Oh, and btw, the back barrels top butterfly's only kick in under load so this is a drive test deal for a Sat. afternoon.

pdq67

 

good luck

 

Yes! X2

 

The 17087124 is off a 85-87 Truck, it has a connector for a dual capacity accelerator pump, which uses the Coolant temp to change pump capacity, more cold. The 5001 is a more conventional carb but does have APT or adjustable part throttle. It is an 85-87 Truck calibration.

The first 2 have Electric Chokes.

The 17058213 is a 78 Truck/Marine calibration with a divorced choke. That means you have to have the thermostatic coil in the manifold.

If you are mechanically inclined you could likely adapt the electric choke parts over.

Hoop

 

rhopper has given you the best advice on here,,, Q jets are a great carb when they are rebuilt RIGHT,, there is no magic to them, Read the Ruggles book and buy the right kit for your application,, I have never met anybody who knows more about them than Cliff Ruggles. You can go to his forum and get a lot of info.

 

I'll second getting the book but I think the 2 newer carbs will be harder to setup.

I've got a copy around here and wouldn't start without it even though I did a thousand or so back in the day. Way too many combinations to remember.

rhooper with 1 P

 

Yes , with one P,, I would not make a good secretary,,,,, i can tell you have been around them with the APT statement

 

Look for one with the big primary venturies and the air valve on the sec that opens all the way some of the early cads had the big ones on them and the fuel inlet in the same place as the chevys.

 

I like the APT carbs but they are not as friendly to new carb guys.

The 78 Carb calibration should be close if it is in good shape. If you want good mileage the power piston or primary metering rod spring is where to play.
IMHO


Google quadrajet power piston springs for more info

Because the 78 was calibrated for part throttle EGR it is calibrated for low vacuum, with 2 springs, and may be off with no EGR.

BTW, vacuum advance units and vacuum modulators will be off with no EGR, you should use 72 and earlier ones with no EGR,

For best mileage you want the weakest spring that is ok for driveability.

Hoop

 

I have cliff's book, and have read a few chapters. He basically states that almost any quad is a good start, as they all only vary slightly after 76.

So the 7124 doesnt have APT? I'm leaning towards using it because I wouldnt mind playing with the dual capacity accelerator pump. Also it already has the mixture screw caps removed from the baseplate, and like i said before, looks super clean inside and out.

I imagine I can mix and match most parts between the 3 too, metering rods, power valves, maybe a choke pulloff?

 

I think you are set, if you have the book no use asking on here call Cliff he doesn't mind answering questions and he will also answer on his forum.

 

Cool, at least I know I'm heading in the right direction

 

Besides what the nay sayers think , If you do that carb RIGHT you will be happy in all respects,, I did one for my son on a 355 ci sbc with around 400 hp like yours, i did put some time in on tuning it, but the results were a sweet running motor that started ALMOST as fast as a tbi/tpi. He drove back and forth to college on weekends and it got 17-18 mpg cruising and about 14-15 around town, and this was in a heavy pick up truck that would light the tires up from a 10-15 roll.Also would pass the state emission sniff check, Doing one for my 57 truck at the moment.

 

Another option, if you aren't picky about authenticity, is to use a Holley 4175 Q-jet replacement carb instead. I have one here for sale that had less than 500 miles on it on a Buick 350 motor before I pulled it and did an engine swap for a Ford 5.0 EFI motor. The carb is in virtually new condition. Summit currently lists them for $429.95 in their catalog./ I'll sell mine here for $275 out the door. Email me at [email protected] if you are interested.

 

thanks but no thanks. The initial reason i decided to try my hand at building a quad is because funds are tight right now haha

 

Nope, not Canadian. Maybe Ukrainian export Z-28??

 

Or maybe B S

 

Friggin jokers...

I guess I should have said taken out of rather than from...
It didn't have the "correct" engine in it either, since it said it was a 350.
Anyway, the numbers on it are 07029207 and it came out of a Camaro with Z28 decals/trim on it.