Q-jets... some of us knew this for decades...

[nvrstuk]

The short video doesn't even mention what wheelers called them for 20 yrs...

"Poor man's fuel injection".

https://www.facebook.com/share/v/1EZvbhnM44/

Edit: what happened to the title??? lol

 

[73azbronco]

I think they work because they are simple, not complex

 

[ssray]

Decided to take a look at the Qjet here and found something I dont remember running into. A mesh screen with fabric under the secondaries??? This is on the 455.

 

[ntsqd]

I'll guess its to attempt to re-atomize any liquid fuel that drops down onto it.

 

[nvrstuk]

Bet they did that after OPEC screwed us!! Just guessing...

 

[ssray]

I'll guess its to attempt to re-atomize any liquid fuel that drops down onto it.

Well it maybe works...I think Dad had gotten up to 17 mpg on the highway in that big BonnieV. T400 so no overdrive gear. 124 cc low compression heads so you could throw on a couple turbos and a 6 spd for power and economy.

 

[ssray]

Bet they did that after OPEC screwed us!! Just guessing...

Yea, it seems like 70 was the last year with decent compression. This one was a 75. There were some 400's in the late seventies with around 100 cc. Those would bring it up some if there were any still around...else its aftermarket and big $$$.

 

[gnpenning]

Never seen that as original. I would like to see the base gasket and how they sealed the screen. Looks like a big mesh. Is it possible that your dad did/had someone do it?

I've seen motorcycles with a small mesh.

 

[MarsChariot]

Autolite 4100 is dead simple and better than fuel injection in my experience. I haven't looked at another carb since. My fuel injected motor is too fussy IMO.

 

[ssray]

Never seen that as original. I would like to see the base gasket and how they sealed the screen. Looks like a big mesh. Is it possible that your dad did/had someone do it?

I've seen motorcycles with a small mesh.

I can't really tell a lot other than it looks somewhat angled. I'll pull it off and see what's up with it. I'll have to make some notes on vacuum lines etc to understand it better. Ive been wanting to weld up a stand for the engine as well and see what the oil and cylinders look like.
Dad was good with engines. He grew up in Chicago, went to Lane Tech which had an auto shop as well as other tech areas. I can't remamber him doing a lot as this was the family car and we had a excellent mechanic at the dealership. But I did find this on the fuel line, thanks to articles in the old magazines. Evidently couldn't resist trying it.

 

[nvrstuk]

I am beginning to think maybe I need to do change my vacations to sand drags & Route 66 cruising... then run a Qjet for EZ start it up every time!

 

[ssray]

I am beginning to think maybe I need to do change my vacations to sand drags & Route 66 cruising... then run a Qjet for EZ start it up every time! know s9m3

I know some guys that cruised 66 and really enjoyed it. Lots of sand to my north, but there's stuff growing on all of it. Still having a tough time with the terminator?

FWIW you can edit your title if you do it from the first post.

 

[nvrstuk]

I know some guys that cruised 66 and really enjoyed it. Lots of sand to my north, but there's stuff growing on all of it. Still having a tough time with the terminator?

FWIW you can edit your title if you do it from the first post.

Thanks- I'll try that edit...

 

[72_EB]

I am guilty of one of those people in the video that gave up on tuning one. Although, I think my issue was a couple of burnt valves on the back of a 302. It was fun when you mashed the petal and those fat secondaries opened. I was hoping for mileage and offroadabilty, but went back to Autolites as I’ve been witness to those idling at pretty much vertical. I need to dig up the old video of buddy Kurt’s rig with a C4 starving for shifting juice on that incline while the Autolite idled away.

 

[nvrstuk]

Qjets would hang with the Autolite 2 bbl in extreme off camber but the Autolite just barely had the advantage.

My last issue with the Qjet was having enough fuel pressure to deliver enough fuel to have available in the bowl at WOT with 600HP & then 2 minutes later not have that same amount of fuel available in the bowl for extreme, really extreme off camber stuff as it would stumble.

TS could come up with a good work around with electric flow & pressure regulators but I thought SEFI would solve all my problems... instead...

Stock works but I haven't had a stock engine in my Bronco since 1977...

Ain't going backwards...just not an option.

Maybe the key to reliability, & yup I've thought of this a lot... is to go to a stock ECU again (but not piggy backing with a Moates setup) & have it tuned (since all the internals are stock) swap over all the stock sensors & buy 4 more of each OE sensor & another couple OE ECU's at junk yards.

Course there is no stock OE ecu that supports a 351W block with large HP #'s... what checks all these reliability boxes are these two options:

- a stock ecu for an engine with just a tune what engine & what manufacturer?

-new sensors that are OE QUALITY not Echlin that's now made in China that fail in 2 months of run time. For many that may be 5 yrs of use but for me that's 2 months of use.

- current Ford engine that can make the power #'s I want reliably is the 7.3 Godzilla

- current engine platform that was recently produced & stock OE reliable parts are available for it & will be for the foreseeable future is the LS. I know a guy here & several others... lol


... hmmmmm

OE quality ECU & OE quality sensors are only available & correct me if I'm wrong, are off OE vehicles that are new or almost new (6 yrs Ford).

Let the comments & debate continue

 

[ntsqd]

MISF has spent a bunch of time tuning Q-Jets and I've watched some of it. And witnessed/experienced the results. There was a period of time where he had almost unlimited access to a O-Scope, a three gas analyzer, and importantly both a fwy commute and Toro Cyn Rd. He learned a lot about tuning a Q-Jet by making a change and then seeing how it performed. Adjust, test, adjust, test, adjust.......
End result was a 400 inch Pontiac in a ~5000 lbs car that got 16 mpg at normal fwy speeds if you kept yer foot out of it (not 'hyper-miling' but just being careful) and would sustain 110 mph as long as the fuel supply held out (about 50 mins by one test). It obviously wasn't getting 16 while going 110....

The thing that struck me was how low a Q-Jet's desired supply pressure is. If I recall correctly the books all say 4psi. Can run the pressure up, but it starts messing with the metering or over-flowing the bowl.

Decades ago I read an article about "dry-sumping" a carb. I think that it was in the context of racing an ACVW off-road, but past that I've no idea where the article was. Essentially you replace the needle and float with a stand-pipe. The height of the stand-pipe sets the "float level" and is connected to a pump that pushes whatever fuel falls into the stand-pipe back to the fuel tank or a surge tank. The seat for the needle is replaced with a jet that can flow just a little more fuel than the engine can consume at maximum demand. And finally the whole fuel bowl is stuffed with fuel cell foam to control slosh. Delivery pump pushes fuel to the carb, whatever isn't consumed goes back to the tank via the stand-pipe and return pump. You want to over-shoot max demand by a little bit so that the return pump is never running totally dry. The return pump needs to have almost as much GPM as the supply pump or idle will go rich.
The two liter in the avatar couldn't run on a stock ACVW carb so I was in the process of assembling a near stock 1600 to test the stock carb that I'd already modified when life took a turn and I had to shelve the whole thing. I dearly wanted to get back to it, but that never happened.

 

[73azbronco]

I have 4.5psi at the inlet, no issue.

 

[DirtDonk]

I had always heard about how good the Autolite was, but had to laugh when I heard it. Our early experiences with the 2100’s were the opposite.
Every time we’ve hit a hard trail we spent half the time on the starter, trying to restart it. This is with them almost brand new, up to several years old.
It wasn’t until I rode with a friend in his 77 that I realized all the rumors and reputations were true!
That 77 could stand on its nose or on its tail and just sit there idling like nothing it happened. It was shocking!
Makes you wanna find out the differences, or just put a 2150 in place of the old 2100 and see if that makes a difference. Perhaps there were tuning strategies that I was not following, but we never had that luck with our ‘72 and older Broncos.
I’m a bit Quadrajet fan myself. But never got around to adapting one to the Broncos.
And now it’s all about EFI.

 

[nvrstuk]

Not saying I knew what I was doing but I sold quite a few and many of those are still running. That really means nothing but Chuck from BC Broncos "lost" a carb at an SOB at Sand Lake back around 2000 and he borrowed one I had. He asked if he could take it home with him and I said "Sure, if you send it back!" " It took a while but I got it back and lo and behold he had an outfit contracted to sell rebuilt Q-jets thru BC Broncos not long afterwards.

They worked amazing and yes, best mileage of any carb or EFI on a 2,000+ mile trip to the Rubicon and back with 8 other Broncos. Several were almost brand new Exploder take out engines w/efi and they never got better mileage than I did with a 351w, bit of a rowdy cam and my Qjet.... EVEN while crawling the Con for 4 days as everybody thought the EFI on a 5.0 would get better mileage... nope. We drove in a line and filled up at the same gas stations. Kinda of an accurate test.

 

[gnpenning]

HUGE fan of both the Qjet and 2100 carbs. Like many I've learned some things the hard way with both. Been 4 wheeling longer with Qjets in my square bodies, didn't start with Broncos until 92 about a decade and half later. Never understood why people have used other carbs on either both with a touch of knowledge are excellent on and off road. Angles can be overcome.

Putting together the parts for my first Qjet Bronco and looking forward to the results. Moving to an Edelbrock manifold or I would be happy staying with the 2100. Ease of trail side repair is a major factor along with really nothing to break or fail are major reasons for me. A bunch of the places I go don't get much if any traffic with no service, to far of a hike anymore. Dependability above all else. The only downside is ethanol. I drive square bodies almost weekly and they can sit for weeks at a time before I get back to that particular one. I do find a electric primer pump on 1 of them reduces crank time after a long break. After, it's good to go, no issues the next day or so of sitting. Takes over a week of sitting to need the pusher pump. Switch off until the next time.