Hi All,
Looking to swap out a rebuilt but worn out 750 QJet and want to try something new & reasonable - Holley, Demon, Edelbrock. Prefer vacuum secondary's & electric choke. Want something that will get off the line quickly and smoothly, and will still get ok mileage if right foot behaves.

71 Cutlass Supreme Conv. with a rebuilt '73 - 455 bored .030 over, forged 10:1 pistons, 3 angle valve work on stock heads
Compression: originally 8.5:1 - approx. 9.+:1 now
Comp Cam: 42-208-4 (everyday perf dual pattern) Lift: I=.472 E=.486 Duration: I= 265 E=273
Exhaust: Hooker Headers w/ 2.5” pipe & turbos
Carb: 750 QJet on Edelbrock Performer Olds 455 alum intake
Trans: 1971 TH350 w shift kit & perf clutches; higher stall T Converter
Open 2.73 rear end (& yes a 3.31+ posi would be better for sure, but not in the cards currently)

Tnx for your recommendation & expertise!

 

Get the Q-Jet rebuilt by a specialist. You’re not going to fix 50 years of wear and tear with a 30 dollar Autozone rebuild kit.

 

Q-Jet is good, I didn't have one I have Street Demon 1904 750cfm carb on my mild 455 and it runs well. It's like an AFB, tunes with springs and rods for the primaries and jets for the secondaries. My only complaint is that the carb has to be removed to change jets because all of the screws are accessed from the bottom of the carb.

 

Edelbrocks, Quickfuels, and the likes are all good. Super easy to tune. It is a matter of preference. The Qjets have there place also. I have a Ebrock on my 455 and it runs great. Super reliable.

 

Edelbrock or Holley would be preferable in my book vs. a Demon. FWIW, I have a Summit carburetor on my 71 98. It's a Holley clone and runs good for the price. Whichever one you get make sure you keep ahold of the Quadrajet.

 

Thanks Folks, much appreciated. I do love the stock QJet look and spread bore design. My 750 QJet is worn out - fuel inlet JB welded, runs dry after a couple of days (even w/epoxied plugs). I just want to get in and go w/o having to pouring gas into the carb. Afraid a new QJet might have same issue. Ok to go with straight bore Holley or Edlebrock? My performer intake will accept either bolt pattern.
I'm leaning towards either a Holley 4160 750 or a EB 1411 750 (prefer vacuum secondary's and this one is not).
Tnx!

 

A custom 800 cfm Qjet might be exactly what you want. Or a Holley style, whatever brand has the best price and reviews. The Street Demon 750 is made by Holley, a new 3 barrel casting heavily based on the Thermoquad. The fixed a bunch of the Thermoquad issues. The only issue people have had is secondary fuel supply on high performance motors. Otherwise basically a new spreadbore carb that will also fit a square bore intake.

 

A true Quick Fuel is the only one I would recommend today. And buy a wideband to tune it right.

 

All carbs run dry after a couple of days, because of the ethanol in the gas. If that's your only problem, there is no need to replace your carb. You don't need to pour gas in the carb. If your fuel pump, lines and pickup in the tank are good then cranking for about 5 seconds should refill the carb float bowl.

 

I would agree. If it ain’t broke, don’t fix it.

 

Back in the 80s I swapped my QJet for a Holley 600 vacuum secondary carb. Spent lots of time and money to get it to launch as well as the QJet, then found it got worse mileage on the highway than it did in town. I put the QJet back on after that.

 

You could always put an electric fuel pump on to prime the carb if you don't want to crank on it. You would not need it for the car to run but it would not hurt. Just put it on a toggle switch and turn it on for a few seconds before you start the car. Should start right up.

 

I've been using Stage II quadrajets from SMI for 15 years or so. They do quality rebuilds one at a time, have a bit of a backlog (good).

I tried Holley in my youth, but eventually went back to the qjet for more precise & economical metering. Plus Holley's look a little funny on Olds motors to me. No knock, just not factory enough for me.

I just paid about $600 for a performance 800cfm 170 (later) series qjet jetted by them to my specs delivered to my house. Used to be cheaper, but so was everything.

I'm happy with all I've bought from them over the years. Sean Murphy Induction is the string which will allow you to find them. I have no affiliation other than happy customer.

Cheers
Chris

 

In case my experience helps, I run my cars every week, but not every day. The fun I get is using them to run kids around, get groceries and so on. Not so much shows and judging.

They often sit a few days between drives. Generally I have to crank the engine over a few times (not in a bad way) to pump the fuel up to the carb bowl before it'll start.

I've always believed this is fuel evaporation in the bowl. I don't believe this is qjet-only problem. The fix is just crank the engine over a few times, stab the throttle & go.

However, if your well plugs are leaking (and they do sometimes) that will exacerbate the start up problem as the fuel both evaporates & leaks down into the intake through the well plugs. That's one reason I use SMI quality rebuilds.

Qjet, Holly, AFB, fuel injection, multiport fuel injection all work well, to me it's down to your desires and preferences.

Cheers
Chris

 

I just realized that none of us have said that if you swap carburetors, it is not a simple bolt on and go process. Expect to go through a complete tuning process of experimenting with different jets, metering rods, power pump settings, etc that may involve a wide band oxygen sensor and a gauge to monitor the results of the changes. It can be fun if you enjoy that sort of thing, and if not it can be perceived as a total PITA.

 

This!^^
Now, your q has problems, but you can get them fixed up by the likes of Sparkys, Everyday Performance, or Dean O (still alive?). Aftermarket carbs bring more problems, as most need tuning.

 

Search around for a late model BOP front feed.
A good core runs about $60-$80 around here and Cliffs kit will run $150 give or take.
Snag a Cliff Ruggles,Doug Roe, Everyday Performance book and have at it.
My experience has only been with Cliffs parts and they are good. Sure there are others.
If you call him he will set you up with a custom kit to match your rig. Always helpfull with tech calls.
His acc. pumps are lifetime guaranteed for this new fuel as well.
A little time and money and you have some pride to say "yup I did that"
Ask plenty of ?? here and someone will help.

 

ALL carbs need tuning via a wideband O2.
And from what I’ve seen lately, I wouldn’t let Dean Oliver or Everyday performance even touch the carb on my lawnmower.

 

🤣🤣🤣🤣🤣🤣
I was just throwing names out there. Who's the go to q-jet guy now?
Everyday gets a lot of praise in the G body world. He flat told me he couldn't do one for my needs, and I respect that. He could have easily screwed me over and led me down the garden path.

 

Sparky did a great job ob my Q Jet and the car has never ran better

http://www.sparkyscarbs.com/

 

The closest one most recently was a carb that Cliff did about 5 years ago. Two of the worst I’ve come across were from Dean O and Ken at Everyday. Leaks, incorrectly adjust linkages, bad calibrations, etc. And Ken was absolutely no help whatsoever.

 

I get parts from Cliff and build my own. Cliff also had nothing good say about Everyday Performance. He did an OK job on the main rebuild on my 78 403. There is damage to the main body, the choke started sticking out of the blue. He did send me the wrong parts for free. Looked like it was dropped, I had to add a couple of washers between the body and choke housing.

 

Thanks folks-much appreciated advice, this is great info!

 

Ken ground the tab that limits the secondary air door travel. It opened too far afterwards.
In addition there were other issues as mentioned. He wanted me to send it back and forth until it was fixed, at my expense. Bullshyt.
He also “rebuilt” my customers’ distributor. It didn’t work worth a crap either, inconsistent dwell and the vacuum canister didn’t work.

 

Not cool, sounds like a very unpleasant experience. Exactly why I do as much as I can myself.