Quadrajet owners

[bronco_daddy]

Thinking about one, where is a good place to get one and what are its pitfalls. Looked at BG Demon Jr but there appears to be a lot of issues lately, Holley and Edelbrock...it will either be Edelbrock or a Quadrajet. All I see is 750cfm and that seems to be a bit too much. 302, automatic, hedman headers, edelbrock performer intake dual plane, Mallory Comp Lite 9000 ignition, mild cam.

 

[Thomas H.]

I would also ask which carb and fuel pump is best for 4x4 trails / rockcrawling.
I'll be watching for my friend.

 

[bronco_daddy]

smells like a trap ,hahaha!

 

[phred]

jet performance q-jet from bcb. good carb. not mileage friendly but its in a bronco. A little more of a headache to tune and rebuild.

 

[broncomitch]

my buddy had a rare q-jet on his ram charger.

I was shocked how well it did off road, his trans would cutout before the carb did on steep climbs.
if i was not so lazy i would go find one. %)

 

[blubuckaroo]

A 750 QJ is good since the primary venturis are so teenie. I used to rebuild lots of them back in the day. The biggest problem was the leaky port plugs. It would cause the thing to run very rich. That can usually be eliminated by sealing over the plugs with JB Weld. Another thing is they are a bit finiky about crud in the gas. I usually eliminate the internal filter and use a good inline one. The positive attributes are that they have only one very small float bowl. That keeps sloshing to a minimum. The best part is the very small primary venturis. That will keep velocity up and the throttle crisp.
Funny thing is that back when those were used we threw them away by the box full! They seem to be all the rage now.

 

[broncnaz]

Qjets either run or they dont. I've seen a lot have issues worst than any of the other carbs. I use qjunks for door stops.
That aside while they are 750 cfm you only use what the engine requires as they are vacuum secondary carbs so they will only open as far as the engine requires. Other things about qjunks they require a adapter to install may also require throttle linkage mods and may not fit under a stock hood without a body lift.
Yes BG carbs have had some issues I have one demon jr 525 cfm its been good for me I did clean it out before installing it as it had some metal shavings left in it from machining. Other than that I've had it on for about a year minus a month that I tested out a edelbrock carb. All in all the demon jr has better power and mileage best I could pull out of the eldebrock was 15mpg best I've pulled out of the demon has been 17 mpg. The demon beats the edelbrock hands down offroad as well. Usaully I run standard 600cfm holley 4 barrels on of these days I put one back on to see what mileage I can pull of it them. I only went with a demon because I found one cheap and its basically a holley carb so I knew I could tune it and get parts easily and I knew it would run well offroad.

 

[bronco_daddy]

Broncnaz.. .you have my interest piqued on the Demon Jr..I want to like the carb given all the other carbs and their inherent problems...the 525 has been good for you and as you spoke of the metal shavings have been the bigger issue. Maybe I will give Jegs a call and ask about warranty issues and return policies..cause I am about done fighting with this FI. Been told that the Demon runs like an FI system when dialed in..curious, do you have an automatic and if so how is there setup for the throttle kick down? Would like to get your tuning specs also.

 

[merlin]

get a q-jet from bc. the red-neck fullie...............

 

[broncnaz]

I'm not running auto tranny but I did get the kickdown linkage with it. I'm not fully aware of all the issues with demon carbs most seem to be due to the shavings left in side them and poor customer service from BG. Anything else happening with these carbs is probably more due to tuning issues of the buy than anything else. Worst case just go with one of Holley's TA carbs the 470 CFM seems to be working well for most guys and they sem to have good customer service.

The only change I've made to the carb is to go up one size in jetting. But I run a 266 dur cam and have TFS heads with a RPM type manifold. So on a relatively stock 302 or one without big heads anyways it may not require any jetting change.

 

[bronco_daddy]

JET Quadrajet

JEGS has the Stage 2 at a much better price plus no sales tax ;D

Here is a question...no body lift but has hole in hood for scoop for the carb and a 13.5 air cleaner will fit under it all? I really don't need another project at this point i:e; body lift

btw...these are electric choke, yes?

 

[Oatmeal]

JEGS has the Stage 2 at a much better price plus no sales tax ;D

Here is a question...no body lift but has hole in hood for scoop for the carb and a 13.5 air cleaner will fit under it all? I really don't need another project at this point i:e; body lift

btw...these are electric choke, yes?

I ran a Q-jet on a slightly warmed up 302 for several years. I had mine mounted on an early Mustang cast iron 4bl intake via a modified Transdapt 4 hole Holley to Q-jet intake adapter (upside down;D) and it fit under the stock hood with a dropped base 14"x3" K&N. Loved that setup, would damn near run on it's side and returned great mileage. Did you give up on the Pro-Jection setup?---------Hans

 

[bronco_daddy]

Hi Hans...

Saturday I am tackling the Holley FI...I had to go to Los Angeles and get my FI cleaning machine which has diagnostics for fuel pressures incoming and out going plus I can fire each injector individually...it looks like I have leak down also in the injectors causing start ups after an over night sit to be horrid and my oil is fuelie in smell so I have to dump that.

So here is my plan: test the incoming pressure, check for return line pressure, clean the system at a higher % of ammonia soap based cleaner to really dissolve the resin binders plus it will clean the 02 sensor and intake and exhaust valves...I do this for 15 mins at approx 1000 RPM. Take a timing light and find what cylinder is timed closest and you can view easily your spray pattern through throttle range plus and drops within the pattern which causes issues. Lastly I do a high pressure cleaning by increasing the fuel pressure and restricting the return pressure and doing this for 5 minutes..a great cleaning is achieved.

I have not given the system the full benefit of the doubt..it is sooooooo erratic that I just have no patience going into this and personally see it as a waste of time and that is the wrong mind set. Yesterday, it was starting like it had jumped time..pissed me off royally. Got it started, warmed it up and took off like a flippant raped ape and then two blocks later running like crap off the start...no two city blocks are the same and maybe I have a pump issue also.. but at this point i rather just scrap everything and go with new everything so I know where I am at. I am the type of person that hates not knowing anything about the quality, how well was it installed and the age of something. I use top stuff, my installs are impeccable and made to come apart readily 40 years later and this FI system has me twisted.

What do I expect? TBI will most likely be off (I hope) and psi is probably too low pressure side and maybe there is a back pressure. I have a guy that is supposed to be top shelf on this system working with me via internet so we will see. The injectors will be clean and I am more after getting my valves cleaned and the 02 sensor. Checked plugs and was actually surprised to see a lean burn light tan and that is discerning...with this much fuel dumping at low RPM and not enough on the high side.

I would like the system to work and work well with acceptable reliability. I feel overall it will not give me what I want and will go with either the Quadrajet 750 cfm from JET or the 525 cfm Demon Jr..I need to talk to both companies because I do not want to swap one headache for another and I want peak performance.

 

[Madgyver]

The QJet fit on the firebronco with a stock hood, no body lift. I tried it and it cleared. Adaptor and air cleaner cleared fine. Runs a whole lot better than the Edelbrock that I had on there before.