Technical Rochester Quadrajet

I've been offered a couple of Quadrajets for my budget project, but have no experience with them having always been a Holley guy.
Are they reliable?
Can they be tuned easily?
Any quirks I need to be aware of?

Or should I just forget them and save for Holleys?

Thanks for any input

 

There are a lot of different Qjets, they were used from 1965 to at least 1986. Later ones had computer control, there were several different types of chokes used on them, different linkage, different fuel inlet locations, etc. If you get a carb that was designed to work on the engine you have, and the engine is mostly stock, they can work great. Unless there is something wrong, like a warped body, worn throttle shafts, bent or missing parts, wrong parts, etc.

Post pics of them, tell us what you plan to put it on, and we might be able to give you a guess if one would work.

 

They are great carburetors! Harder to rebuild, and tune, than a Holley, but they usually work much better, make the same power, and get better mileage. Stay away from the computer models, as Squirrel said.

 

Great book if you do get into one, can probably scoop a used one off fleabay for lunch money

 

Better carb than any stock out of the box Holley ever was ....

 

I like them...

 

I have a local shop that does a great job rebuilding them. My success is about 50-50 so I leave it to the experts. The last one I had done was on an OT 1979 Chevy wagon and it ran fine after. This is the last year before they went computer. This one shop rebuilt my carry-in, told me to install it and bring the car back and they'd set it up, which I did and it was all part of the rebuild.

 

Me too. Someone should make a big plastic Holley double pumper looking cover for them, held down by the air cleaner screw, for the guys who don't like the looks. To go with the Hemi-look valve covers.

 

If you get one to run as good as this one sounds you'll be all set.

 

I have one on my convertible the one that came on the 455 I put in the car. It runs great, wouldn't put anything else on the engine

 

met MR Roe years ago when I raced , he p***ed away several years ago , the man was full of information and knew the carb like the back of his hand . and his book is full of all sorts of good info

as for a Q jet , great carb , and actually simple when you get down to it , the best ones are the 70 series ( pre 75 ) , as they have more tunability the post 75 have APT and are more specific to the vehicle it was designed for , but once a base tune is set up basically all the fine tuning is with the secondary needles .

and its great now as there are more suppliers for tuning stuff for them than were when they were around ( even the dealers had a small inventory of parts , and we often had to modify the needles and braze and redrill hangers . )

the electric or dancing needle Carbs were the lead in to EFI ( kind of worked like a crude TBI ) . and you need the matching computer and a O@ sensor on some of them to control them , otherwise they run full rich unplugged . and there is hardly any support for reprogramming Proms for these anymore .

and if they say they aren't a performance carb BUll Squat ! , in Superstock we have gotten into the upper 9's with them ( they are modified a little internally )

 

One name sticks out in my mind. Val Hedworth. Lippy

 

Great carbs! Will get better MPG than a holley due to the APT. Having a wide-band A/F monitor will help dial it in. Lot of good info in Cliff's book.

http://www.cliffshighperformance.com/

 

Kind of out in left field, but has anyone ever made an aftermarket computer set up to work with an electronic metering rod Quadrajet and O2 sensor?

 

They have little "eccentricities" but I like em better than Hollys. When you take the horn off there are four slender br*** tubes that point downward. A lot of times there will be at least one out and laying in the bottom. This is the main reason for "Quadrajet bog" clean the area and stick the tube back in. Run a little bead of epoxy around the base of the tube. The biggest thing is to clean, clean, clean. There are several good threads on here about cleaning carbs. Get you some small diameter wires to run through all the small p***ages. Don't over tighten the needles or you screw up the seats. People tend to adjust the secondary to come in too soon.
Before I rebuild one, I check the lateral movement on the "****erfly" shaft. Too much play and its parts only. Even if you get it right, it will idle high. I don't know of a fix for this. I wish there were one. That's all I know about em and I'm not a guru like some of these guys.

 

Ugly, but good.

 

They make bushing kits to repair the throttle shaft slop in the base plate. There are a few companies that will bush them for you is you send them the base plate. Slop in the secondaries will hang the throttle plates open a crack at idle and make you think the carb is junk. I've amazed lots of customers by tapping on the secondaries and making the carb sound brand new.

 

Well that's probably not true, maybe you like them better but that does not make them better.

@Legendlives good info from Squirrel nothing to ad. If the throttle shafts are loose that can be repaired, I have the proper tools here and may even have some bushings or you can set yourself up to do the same for about 35 bucks give or take a little bit. If the carbs fit your budget there is no reason not to teach yourself how to work on them.

 

If I had 25 cents for each one that GM put on a car or truck I'd be a rich man.

 

There were even some Fords that rolled off the ***embly line with Quadrajets (1970 429 CobraJets).

 

Got acquainted with Quadrajets in the '60s, they were available for cheap.
Local scuttle**** condemned 'em, guys called 'em 'Quadrajunk'. I did some homework, used them for a few years...Great results.

Ditto on the Thermoquad...(remember the 'plastic Carter'?)
My neighbor garage owner said the Thermos were JUNK, replaced a few of them with AFBs. Gave me the old Thermos!
Studied those, and found how smooth and reliable they really were.
Look like **** on flatheads, though...

 

The wait is a little long but one of the best in the business is Sean Murphy Induction (SMI) in Huntington Beach Calif. Many NHRA stock record holders will tell you of his expertise with the Q-Jet. He has done my LSR record setting carbs and many others for years. One of the best in the carb business.

 

The Nailhead likes it

 

I replaced my Holley with a Q - jet. Good reliable carb.

 

I kinda dig em.

 

Put a rebuilt one from Summit on my 60's bored 327 w/electric choke. Fired up like a champ straight out of the box, and with a little tweaking, it settled into a perfect tune that it has held for going on two years now as a street cruiser during all four seasons (30 -90 degree weather). Solid carb, and a good match for a 700R4 trans in a cruiser.

 

Wow! Thanks for all of the replies guys.
On the basis of the information received I've done the deal. My car will have dual Quadrajets on it just like the pic from Panneton Bros Racing up there ^
And if it all goes horribly wrong I can blame you lot!

 

heh...you never posted pictures of them, did you? I hope they work! I keep 5-10 of them on the shelf, and one or two can probably be made to work relatively easily.

 

Just rebuilt a 47 year old one. Other than being a little worn in the primary throttle shaft, works like a new one.