Rochester Qjet problem

Was running good on short trip to auto parts store on thip home statred to run like crap at idle . Got home took off air cleaner saw gas running out into pass side front barrel??  Took top off carb pulled out main metering roda & jets  . Put back together same thing?? switched rods & jets to other side same thing??  I rebuilt it after 13 Nats(it didn't get to go)Sure don't  want to have to get new carb.  Is it just this crappy gas they make us buy??? Any Ideas?? Thanks

sure!!!!!!!!!!!! check that float & area it sits in -metering rods dont effect  that problem!! look 4 trash in the float area!! and remove the needle & seat & replace if ness.

I quit using that style carb in the early 70's -always gave me problems -if u just have to have a carb like that?? get a hollet -they make them !! Put a fuel filter before the carb also. Ive found sometimes -rubber fuel lines will deteriorate & gas tanks will rust -giving crap in the needle & seat area -also replace the float too along with needle & seat!!

What I don't get its Only dripping on the pass side of Primary,drivers side is ok??Thats why I "thought " metering rods & jets for primary???

It sounds like a typical float bowl overflow. I have worked on hundreds of Quadrajets and the Quadrajet is a very reliable carb if you maintain it in good shape. What you need to do is get a good rebuild kit similar to this one that has alcohol resistant float, accelerator pump, and filter.
http://www.ebay.com/itm/Carburetor-Master-Repair-Kit-Quadrajet-72-78-Chevy-Truck-Rochester-Quadrajet-/331200568709?pt=Motors_Car_Truck_Parts_Accessories&hash=item4d1d179d85&vxp=mtr

What happens is that over time the Phenolic plastic float becomes gas-logged and flood the bowl. With alcohol in the gas the phenolic float will deteriorate faster so you need the newer style nitrophyl float which the new kits have.

All quadrajet carbs are good if they are kept clean. Back when I was in the Navy I had a 1970 GMC pickup that had a Carter Quadrajet which was identical to a Rochester.

It's dripping on the Passenger Primary side because it is leaking from the float bowl into a vent on the passenger side. I ran across this before. It can't leak if the float bowl is at the level mark unless there is a flaw or pinhole in the casting or a bad seal somewhere. Clean it up spotless and throw a new kit in it. Make sure all the ports are clean. Quadrajets don't like dirt.

Oh, and if you can find it, stick with non-ethanol gas. It's usually higher priced but better for your engine in the long run.

Thank's GMman, I'll check the float. I remember the accelerator plunger is blue.(updated??) Had problems with bad gas in this van before. Drained,& droped tank,pulled sender ,scok. Blew out(what looked like Mud-oil) from tank to pump line,& rebuilt carb.

Gotta use Stabil the ethanol is "Killing Us"..!!!..                                                           http://www.ebay.com/itm/ROCHESTER-QUADRAJET-4-BARREL-CARBURETOR-4MV-454-7-4-BIG-BLOCK-MECHANICAL-CHOKE-/281293982745?pt=Motors_Car_Truck_Parts_Accessories&hash=item417e6d8c19&vxp=mtr

What's happening is the ethanol is eating the lead plating in the older carbs you can rebuild them over and over and you will still get the corrosion.... The newer carbs don't have that plating... ..I would just throw a new 750 Holly carb on it and be done with it..!!!..JMO..

Quadrajets are excellent carbs.  Set up correctly it will be reliable, outperform a holley and give you better fuel economy doing it too.  I like Holleys, and own several of them, but just because you have a stuck needle & seat or a sunk float in your q-jet is no reason to get a whole different carb?  These guys who are telling you that nonsense are nutty!

Starting in 1967, GM went away from the multiple carbs, and put the Quadrajet on all the classic muscle cars for a good reason!  GM produced millions of cars and trucks with the QJ.  They ran great on everything from a Pontiac OHC-6 sprint 230 on up to a Cadillac 500 and everything in-between.

The key awesome design features to the quadrajet are the little small primaries allowing good fuel economy when cruising light throttle, but then its got those big secondaries for max power when you get your foot in it!  the secondaries air doors on top operate by engine vacuum, and only open as much as your engine needs, in other words, you won't have a problem 'overcarbing' the engine with a quadrajet.  

Rebuild the Q-jet like GMman says.  Use the alcohol resistant parts he recommends in post #4, and set it up right, you'll be glad you did.

Make sure your fuel hoses are not deteriorating, and your tank doesn't have rust in it.  Run an inline filter.  Keep the carb clean.

Awesome forum for Q-jet carbs:

http://www.cliffshighperformance.com/simplemachinesforum/

moderated by Cliff Ruggles: QJ Guru who wrote the quadrajet rebuild book

Yes =ALMOST!!?? GM owned rochester ! wonder why GM used them?? Just wait till you are wanting to replave metering rods & such- took years to offer those to the public too! Ive got old rochesters laying all over in the garage-boxed - always went to hollys & wont quit! Like a chev & ford Thing. I cut my teeth on the old carter AFB's- had a mercruiser teck rep in about 1993-4 having trouble with a full line of V 6 marine engines- couldnt figure why the engines would fall on their face when throttle was showered down on-everyone of the boats stumbled & died!! New engines in new boats & all under warranty too! Came out to our shop from fon du lac= wis. when he herd id found a fix! Edelbroc carbs are the direct copy of those old style carbs (AFB) now a days too. simple carbs - work ok yet - if u want a easily tunable carb - Hollys my bet! Today its easy to find internet charts for engine sizes & rpm & loads for proper holly jetting & other adjustments to them too. Not knocking anyones pereferances here - just after all the years of doing carbs - ill stay with what i find easy & readily available for parts too.

I had my Q-Jet carb rebuilt last year and it took 3 different kits to get the job done, and $300.00 bucks. I asked my guru what he thought about changing the carb to something else. His answer was...When I can no longer get parts then you should change to something else....lol. When I lay down that pedal there's no hesitation, no bogging just get up and go. Now the other thing he had to say was that the new Edelbroc carbs are really nice and easy to tune. So when the QJ can't be rebuild any more...then I will switch to Edelbroc.

Think I'm going to wear out carb taking it aprt so many times.Got it down to about 5 min  getting it off van. Still same problemDripping on pas side main) . Complet tear down & clean & blow out,float was fine,put in new seat & neddle for float,all new upgraded gaskets??? Got feeling R primary metering rods not seating right???
Hey Matt you want to get rid of some Qjets(LOL)

Joe Van wrote:What's happening is the ethanol is eating the lead plating in the older carbs you can rebuild them over and over and you will still get the corrosion.... The newer carbs don't have that plating... ..I would just throw a new 750 Holly carb on it and be done with it..!!!..JMO..

Tom do what I have been doing lately sell some parts that you dont need or have two of and buy a "New Carb".... The new Holly Advenger carb is Bad A$$.!!!.. I had a 770 on my Big Block 41 Willys "Effortless Power" ...Plus like Twin said they are the most tuneable.. .........The point I am trying to make is getting a "New Carb" verse rebuilding a 30 year old one no mater what kind it is Holly,Edelbrock,Carter.Q Jet, it will be able to handle the ethonal and unleaded gas unlike the old ones from the 70's that are designed to run on "Regular Leaded" gas and that have lead plateing inside them..!!!...Call me Nutty its  JMO and past experience....

Joe=is =TOTALLY CORRECT!! Us =old guys have been thru & seen it all Not trying to mislead anyone. Just trying tio give those the benefit of out =LONG PAST EXPERIENCES!!

You know if you think about it 20-25 years ago most all repair shops rebuilt carbs..!!!..We had 3-4 shops locally that would just rebuild carburetor's....  A&S Carburetor was one of them that's all they did.... Since then they have all closed down just like the old school radiator shops that repair/recore Copper/Brass Rad's they are few and far between..Rebuilding carbs is becoming like rebuilding your alternator or starter you just don't hear of it anymore..Years ago I had hundreds of carbs rebuilt from A&S Carburetor at our shop but with the ethanol NOW it is eating the older ones from the inside out....(it Looks like Barnicals) I rebuilt the Holly 600 on my 1966 Chevy Nova 3 times with all new parts but 2-3 months later I had the same problems would not idle right stumbles on take offs rebuild it again and it would be fine for a while finally I bought a new one and never had a carb issue with it again..Samething with my 1962 Bel_Air...I am "Old School" also but there are something's that should just be replaced like starters and alternators I think we can add carburetor's to the list also..!!!..Don't flip out on me guys I just have not had any luck with rebuilding older carb in probley 15 years or more... .

There must be a simple reason it keeps flooding from that one side only.  I like the idea to try swapping out the metering rod that is suspect.  If you can't figure out your QJ problem, post on that forum I referenced above, you will receive an answer from Cliff Ruggles, he is the QJ guru.  He is very helpful.  You can also email him, or call him directly with quadrajet questions.  His phone number is listed on his website.  http://www.cliffshighperformance.com  He is the author of the SA Design book, "How to rebuild and modify Rochester Quadrajet Carburetors", and very well respected on the performanceyears Pontiac forum.  Us pontiac guys are big fans of the Quadrajet because thats the carb that came on most GTO's and TransAms, and when they are dialed in correctly, they really do perform well.  

Rebuild with quality alcohol compatible parts, and I don't think you'll have any problem with running an older carb on modern fuel.  

Thank's for all your input. I'm going to try the rods before I give up(rods on way along with another parts carb) This new gas is messing everthing up. You never know if its a good or bad bach.
KK been on that site a Ton of info(read over 10 pages,had to take a break & let it sink in)
Don't want to buy new carb for the 68 van ,got new upgades for it over winter(I hope)

Good for you Savage.  You don't need to buy a new carb.  LOL  you can fix the one you have.

Ethanol in modern gas is not as big a deal as many are trying to say that it is.  Much of what I am reading here sounds like rumor and voodoo by people who don't know what they are talking about.  To make blanket statements like 'all old carbs are no good', or 'you just need to buy a new carb', seems ignorant.  The 10% alcohol does attack natural rubber components and cause them to break down faster.  You can purchase alcohol compatible quadrajet carb rebuild kits from Cliff Ruggles and other sources to rebuild your carb so it will handle ethanol fuel no problem.

Regarding corrosion in the fuel bowl, from what I read, this problem is limited to a certain batch of holley carbs.  Joe Van mentioned his problem was on a holley 600.  There was a run of really crappy holley carbs that resulted in advanced corrosion issues in the fuel bowls and also the main venturi body.  This was due to poor quality control by holley and their use of low quality alloy and bad metallurgy.  Holley has acknowledged that there were some serious plating and metalurgy problems from certain model carburetors made in 2006.  If you have one of these carbs, holley will warranty it and send you a new one.  

Here are two places I found discussion of this problem and the holley warranty replacement:

http://www.camaros.org/forum/index.php?topic=8850.0
http://vb.foureyedpride.com/showthread.php?151142-Badly-corroded-Holley-carb

If you do google searches, you'll come up with many more threads about corroded holleys.

I rebuild, and have always used older carburetors in my vehicles.  I use whatever gas they sell at the corner station.  I have not experienced corrosion on hard parts in any of my older carbs.  I've been building cars for years and have never bought a new carb.  Probably never will.  It makes no sense.  I am aware of this potential problem with some '06 holleys, so if I ever get one like that its good to know holley will warranty it.

I did also read that ethanol has a greater affinity for water than pure gasoline.  This can become a problem in areas of high humidity.  If I lived in a high humidity area, I would consider plumbing in a water separator inline in the fuel system.

If I ever do buy a 'new' carb, I would consider the new street demon carbs. They are based on the carter thermoquad design, and they look very impressive.

Calm DOWN JOE!!! There are those of us that KNOW what were talking about & doing!! and those out there =that are the types that wish they knew what we've already forgotten!!

EASY BUDDY!!

Obviously it would be best if we did not have ethanol in our gas, but we do.  I'm just am offering that there seems to be misconceptions being perpetuated here.  Joe, you obviously feel very strongly about it, and I'm sorry if you took what I said as a personal attack.  I did not intend any personal insult towards you.  

This thread was about a specific quadrajet problem, but then unfortunately it quickly turned into the typical QJ bashing, along with advice that savage should simply junk the QJ and buy a new holley instead.  I respectfully disagree with that, for reasons I've already stated and we don't need to argue about it further.


Yes actually, tell you what, I would even volunteer to rebuild Savage's QJ, just because he's a good guy and have much respect for him. He has been around the vintage van scene, and been a large contributor to both this site and VCVC for years.  I couldn't guarantee success with his carb, but I'm willing to try. It seems like a fun challenge to me.  

I appericate it Kooky..!!!..And If I had the money right now I would just buy Tom a "New" Carb,.!!!..What ever kind he wanted... .

There's got to be a solvable reason why your carb is leaking Savage. Look for any sign of visible damage when you have the carb apart.

Finaly got it running yesterday  Want to Thank everbody for all there input. I was almost ready to pich it out the window(not good when it closed & cold outside) Reset float few more times,new primary & secdary metering rods(sec were so small,think gas was allways running through??) Anyway no more rich smell at idle,or when backing off.  
Now I got a monjet on my Nodoor thats been a pia ever since I rebuilt it(2 times). Runs good at high speed ,but rich as heck at idle,if back off jet it dies.Uses alot of gas sometime otheres not?? I got around 22 going up to G-mans Memorial. Got all winter. Thank's again

Thats great news!!  I'm so glad to read you got it figured out. Good job and way to hang in there and be persistent.  Quadrajets kick ass when set up correctly, but sometimes they can be frustrating because they are not as simple to work on as a holley.  

So to confirm, it was swapping to different metering rods that fixed this problem?



Regarding the monojet, you got 22 mpg?  That is great!!  wow.  sweet.  

Regarding running pig rich at idle sometimes, I have noticed on the monojet on the wikivan that it can experience an intermittent heat soak from transferring heat from the intake after running a long time at sustained RPM, such as freeway operation, then turning the van off.  The heat soak condition causes the fuel in the bowl to boil and I think then it condenses back into the carb and intake, and then causes hard starting and then very rich operation after engine restart.  I did find a phenolic spacer to go between the carb and the intake to hopefully counter this heat soak problem.  I have not gotten around to putting it on yet because I still need to locate longer carb studs.  


Check this listing out, it comes with the longer studs, which is nice.  

http://www.ebay.com/itm/2-BOLT-PHENOLIC-CARBURETOR-SPACER-SMALL-HOT-ROD-RAT-FLATHEAD-VTG-OLD-STYLE-/360696201925?pt=Motors_Car_Truck_Parts_Accessories&hash=item53fb2b42c5&vxp=mtr