Ok, gearhead, let us talk about a QJet in a Slant 6, I also think is a good carb, but I need some assistant to put a QJet in my Slant.

If everyghing goes fine, I will get a 2 barrel intake, so I can modify it to put a 4BBl in.

_________________
Mopar Muscle is well defend by Slant Six!

Valiant Duster 1971

This is how I went about putting a Quadrajet on my engine:

http://cars.rasoenterprises.com/Carb-Quadrajet.htm

I used an Edelbrock adapter mounted upside down but Offenhauser also makes a spreadbore adapter (PN 5816-R) which would probably work much better. If you use a Camaro/Firebird air cleaner, remove the collar from the inside of the air cleaner pan as well.

Frank

Panic is sort of correct, except that the Qjet version of the OHC sprint had quite a cam and was built to rev at 3000 rpm just for cruising. The large cam means the idle circuit will be calibrated in a way that would not work that well unless you are also running a hot cam and ported heads, since the valve size is larger than a slant as well and the ports very large and good flowing stock.

Anyway...I am not well tonight and suffering stomache cramps, and must sleep soon for work early, so can't say much right now...

But, I will get you started thinking...

The issue with Qjet use on models for which they were not designed, is that like any factory carb, the engineers spent millions calibrating the circuits for the specific application for which they came. And Qjets had a lot of different models to make work.

Most of the time, people are looking for the ones that came on hot engines for the rich idle circuit and large air bypass, fortunately for us in slant world, we don't need this...even on fairly hot slants.

If you dissassemble a Qjet from say a Ram Air IV Pontiac 400" engine, you will find a completely different beast in the air bleed and idle circuits, not to mention power piston springs, jets, metering rods(primary and secondary) needle and seat diameter, and a host of other "tuning" differences in the secondary air-valve control and accel pump circuits

...than say, a Qjet that looks outwordly identical but came off a 428" engine in a station wagon with 3.08 gears and towing package...this Qjet would be calibrated for an engine with small valves, high compression, and a tiny cam designed for extremely high vacuum at idle and great low end torque for towing and hauling kids around. But they would both be 750cfm Qjets.

The RA IV carb would work on the 428" engine but would always idle rich and would be difficult to get adjusted without internal carb mods...also, the light power piston spring from the low vacuum huge cammed RA engine would tend to give a mild flat spot on the 428" engine during light accel because the high vacuum would not allow enough part throttle enrichment...and of course, it would get bad milage from being jetted heavy. That said, it would run pretty decent and you'd be happy with all but the milage and possible black plugs after awhile...

As has been shown time and again, and why Qjets get maligned easily by many, is you can't take the lean carb and put it on the RA engine without it idling way to high out of gear(because you need to open the butterflies to get enough air for the low velocity and high overlap cam pulses in the intake, not to mention the very lean idle circuit designed around having alot of vacuum pulling fuel thru a smallish idle jet and small air bleeds because of high turbulance in the heavy pull thru the idle circuit overall. And, once the butterflies are opened that far, the nozzles in the venturi will start to drip because they are so efficient that it doesn't take much airflow to pull fuel thru the main circuit, tricking people into thinking they are rich at idle(they are, but in spite of lean idle circuit calibration, and caused by a dripping venturi nozzle)...then, on top of that...the power piston spring will be so stiff because the 428" small cammed engine had so much vacuum, that the RA engines puny mercury readings will never pull the metering rods down into the lean cruise position, causing rich running at part throttle cruise but lean at part throttle and full throttle accel because of smallish jets...the secondaries, however, will kick in hard and work pretty well anyway...giving the sometimes heard nickname..."QuadraBog"!!!!

As you can see, I could write a book easily about just the idle circuit...but these things are not issues for just Qjets...they are issues for most all carbs...but most carbs, especially aftermarket, are tuned on the generically rich side to overcome the lack of tunability in transition circuits, making them run well, but lacking the ability to truly tune them for economy AND performance...even if you know what you are doing.

They also made 800cfm Qjets...but fortunately, like the venerable Thermoquad(which I also like) they only flow to the cfm requirment of the engine...but that also means you need to understand how to calibrate the secondary metering rod tip length choice vs how far the air valve opens.

But without getting to far since I need to deal with another wave of cramps...you should choose an early 70's core carb from a small cube V8 because it would be darned near impossible to find a good OHC Sprint core for a reasonable price, and since I've built them before, I know for a fact that they are calibrated for a fairly hot engine to start with...and it is easier to tune a Qjet for a hot engine than to de-tune it...at least the idle circuit...meaning, it is easier to drill holes than to fill them(air bleeds, idle jets, air bypass, idle channel restriction ports...etc.).

Luckily, Edelbrock makes jets, metering rods (prime and sec), and different rate power piston springs available in a kit or individually.

There, I've touched the surface, and yet barely got started...this dissertation I will end up writing if this thread stays active will be valuable for people learning about any type of carb, becuase the inherent principles are the same, just different engineered solutions.

I will spend some time tomorrow night assuming I'm not more sick...looking over some of my threads from other writing, and posting links and reasons why they would be of value to Slant owners looking to learn, even if the source material is "slanted" toward Pontiacs.

Gearhead

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

To many threads...not enough time...!!!

Sorry to abandon this thread so quickly...only been able to spend a few minutes at a time on the computer, and just couldn't muster the gumption to go search my posts on the other forum...

That said, I finally did...here is one of the better threads, that if you take the time to follow all of it, you can learn alot about carburater idle circuits in general, and the Qjets...particularly. This thread includes quite a few detail pics during the explanations. I have been carfull to keep my website organized such that these good threads would retain the images for the foreseeable future.

Qjet Idle Tube discussion

This Pontiac Forum, although occasionally full of politics between members, for the most part, and especially throughout the 2000-2003 time period, was a wealth of knowledge interchange by people who truly try to understand how engines work.

Searching my posts from that era...you can learn alot about engines, tuning, and ignition from really knowledgeable people.

Anyway...let me know if you want more info or have specific questions...

Gearhead

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

Ok, thanks gearhead!, I will start reading inmediatly, your ID is GTO Karl?

_________________
Mopar Muscle is well defend by Slant Six!

Valiant Duster 1971

Good thing we don't have any politics between members on THIS forum!

VM

"sort of correct"

Yes, the part that I didn't say (use the carb from a Sprint) is sort of correct.
Perhaps if you read it before finding fault...

_________________

Yes Panic, I noticed that after I had already posted. And I am sorry.

But the fact remains that you implied that the jetting and metering rods would be appropriate, so if looking into a good resource on the subject, and finding that information, my comments would still be a good point to consider in any quadrajet buildup for a given application.

The Sprint Qjet is a high performance carb based on a large cam, large displacement(relative to stock slants), big port, large valve, high rpm application of a six cylinder engine.

I don't discredit your comments, but felt that further explanation was appropriate given what I know about the specific application. I've built five over the years for people, of which...three were stock replacements on original cars, one was for a heavily modified Lemans used for street strip, and one for a Willy's mud bogger in a six cylinder class, that just about tore my head off when we went for a ride...and kicked every inline chevy six butt to be found...

Again, I apologize that I did not correct my statement when I noticed, but since I am working 13-14 hours per day, living in someone elses home, and writing to help fellow slant owners when I should be sleeping...on a borrowed computer...well...that is my excuse.

Gearhead

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"