# WOT issue (Carb?)



## Hot_Rod (Feb 10, 2011)

Hello. My 326 runs pretty good for being in a heavier car like my '70 but it seems to run best when I'm only giving it 1/2 to 3/4 throttle.

When I go WOT the thing doesnt go as well and seems to be gutless. But like I said though, when I go 1/2 to 3/4 throttle it seems to be faster and runs better. What could be wrong? Is it cause its a stockish 326 or is something wrong with the carb? It's a stock Q-jet 750 I think. 4BBL.

Thanks in advance.


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## Eric Animal (Oct 28, 2007)

Your carb could be in need of a rebuild, or it could be too big for a stock 326. Check to see if the secondaries are functioning properly. Eric


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## Instg8ter (Sep 28, 2010)

:agree probably too much carb for the 326


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## Pontiacpurebrred (Jun 22, 2011)

:agree Yea it sounds like you're drowning it at WOT. Too much gas for that engine. You'd probably be better off with a 650 ... at least that would be my guess.


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## Hot_Rod (Feb 10, 2011)

If it is too much carb, what should I go with? I say its a stock 326 but its got a tq'er manifold on it and headers/aftermarket exhuast.

EDIT: 650? It probably wouldnt be a Q-jet then if I did go 650 and stay a 4BBL right?
EDIT #2: I got the car this way so if this is a bonehead setup it wasnt me! Lol.. Also this is my 1st car with a carb on it so I dont know much about carbs. Be patient with me, lol.


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## BearGFR (Aug 25, 2008)

I'm going to differ with conventional wisdom here. Because of the way a Qjet works - when properly set up it's only going to pass the amount of air that the motor wants. That's what those air-valves on top of the secondaries do. The key here is "properly set up". If you're getting "too much" at WOT (and it sounds like you are), then there are two things to try on the carb you already have: 1) different secondary metering rods to lean out the secondaries and/or 2) more tension on the secodary air valve spring to slow down their opening rate and response.

One of the common but misguided changes that Qjet "hackers" have been known to apply in the past has been to loosen up the spring tension on the secondary air valves, subscribing to the "more/bigger/faster must be better" notion that has a nasty way of biting people who don't really understand what they're doing. I'd recommend getting a copy of Cliff Ruggles' excellent book on how to set up a QJet, "How to Rebuild and Modify Rochester Quadrajet Carburetors".

EDIT: To add a little more explanation. To work properly carbs depend on air flow, and to meter fuel properly that air flow has to be at or above a certain velocity. Properly adjusted via the air valve tension spring, the air valves are going to open "just enough" to allow the motor to suck all the air it wants while still keeping the opening "small enough" to keep the air flow velocity high so that the secondary metering circuits "see" the signal they need to dispense the correct amount of fuel. If the spring is "too loose", the valves open "too far" and flow velocity drops "too low" for the metering to be correct. So you dump a bunch of air into the motor without getting the right amount of fuel. Either the mixture goes "too lean" because there's not enough signal to operate the circuit, or the secondary rod hanger (tied to the air valve opening) pulls the rods "too high" and you dump too much fuel into the mix, sending the mixture "too rich". Either way you lose power. 

If the spring is "too tight" the valves don't open "far enough" and the motor doesn't get as much air as it wants, so it doesn't make as much power as it could be.

Qjets aren't Holleys and they don't work the same, just like Pontiacs aren't ::cough spit:: chevys. The CFM rating on a Qjet is actually a reflection of its maximum flow capacity. In reality they can work very well over a broad range of flow rates far below that maximum. They tend to get shortchanged by people who really don't understand them.

Bear


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## Pontiacpurebrred (Jun 22, 2011)

Hot_Rod said:


> If it is too much carb, what should I go with? I say its a stock 326 but its got a tq'er manifold on it and headers/aftermarket exhuast.
> 
> EDIT: 650? It probably wouldnt be a Q-jet then if I did go 650 and stay a 4BBL right?
> EDIT #2: I got the car this way so if this is a bonehead setup it wasnt me! Lol.. Also this is my 1st car with a carb on it so I dont know much about carbs. Be patient with me, lol.


Hey Relax Hotrod, carbs are still a little voodoo and witchcraft to me and I have worked with about 8 different 4bbls in my life. 

Yea there is a 650 Q-jet (or a Carter AFB) out there and you can always go aftermarket with the e-brock carbs they have out there. (I don't believe in holly carbs on Pontiacs, just never had one that worked right) 

Anyway let a few other people chime in before you make a move, I am by far no expert. I only think you may be over carb-ing it from your description of when you stomp it it bogs. I had a 75 400 (pre-rebuild) in my 68 and I dropped an aftermarket manifold and big old 750 or 850 carb on there and it did the exact same thing. Went back to a q-jet (smaller) and it ran great. Then when I re-built the motor (re-cammed - head work - etc.)It was a little thirstier and I went up on carb. 

Anyway, take it slow there's lots of people here to help you.


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## Instg8ter (Sep 28, 2010)

I believe the quadrajet can be tuned down to operate at 650 as most were 750's installed into the 80's and they ran on a lot smaller engines than your 326, sure one of the motor guys can set you straight...:confused


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## freethinker (Nov 14, 2009)

i agree with bear. a quadrajet,set correctly, is not too big for that car. i actually had a stock overhead cam 6 pontiac once that came with a factory quadrajet on it.


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## Hot_Rod (Feb 10, 2011)

Yeah it seems its out of tune/too much carb. 

There's a few things about it not working 100%, WOT of course and then at times its a pain to start depending on the weather. 
Choke isnt working properly and I gotta pump it 2 times on average before I attempt to start it and then I gotta be careful with the throttle if I give it too much it dies and if I dont give it enough it dies... Oh joy, lol.

Once it warms up it isnt an issue. Then theres times it floods easily and will not run right until it clears out. Perfect situation for the 1st time carb car owner right? :willy: :lol:


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## freethinker (Nov 14, 2009)

Hot_Rod said:


> Yeah it seems its out of tune/too much carb.
> 
> There's a few things about it not working 100%, WOT of course and then at times its a pain to start depending on the weather.
> Choke isnt working properly and I gotta pump it 2 times on average before I attempt to start it and then I gotta be careful with the throttle if I give it too much it dies and if I dont give it enough it dies... Oh joy, lol.
> ...



there could be your problem. quadrajet chokes are designed to lock shut the rear air valve until the choke is completely warmed up. if it is not working it may not release it.


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## ALKYGTO (Mar 29, 2010)

Is the rest of your car up to snuff? I did'nt see any reference to the tune. Do you have reletively fresh plugs and wires? You could be running out of fuel or have a bad set of valvesprings. What is the timing set at?

Fuel, spark and air, you need them all.


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## Eric Animal (Oct 28, 2007)

freethinker said:


> there could be your problem. quadrajet chokes are designed to lock shut the rear air valve until the choke is completely warmed up. if it is not working it may not release it.


:agree...and It wouldn't hurt to buy the book. There is a lot of "tune-ability" and adjustments in a Q-JET....they are Excellent carbs.


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## geeteeohguy (Feb 2, 2008)

I agree with Bear and some of the others. Quadrajets came on puny little Chevy 283's, 327's and 305's. Once properly overhauled and calibrated for the engine they're being used on, they are bulletproof and work extremely well. One of the best 4 barrel carbs for the street, if not the best. Welcome to the fourum!!


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## Hot_Rod (Feb 10, 2011)

freethinker said:


> there could be your problem. quadrajet chokes are designed to lock shut the rear air valve until the choke is completely warmed up. if it is not working it may not release it.


Choke hasnt worked on it since I got it so It very well may be.


ALKYGTO said:


> Is the rest of your car up to snuff? I did'nt see any reference to the tune. Do you have reletively fresh plugs and wires? You could be running out of fuel or have a bad set of valvesprings. What is the timing set at?
> 
> Fuel, spark and air, you need them all.


Havnt checked timing to be honest but I did change plugs and have ran fuel additives through the carb and also run 93 octane most of the time.

It runs pretty good nothing really seems to be bad wrong with it other then feeling gutless at WOT.


Eric Animal said:


> :agree...and It wouldn't hurt to buy the book. There is a lot of "tune-ability" and adjustments in a Q-JET....they are Excellent carbs.


People on here say there probably the best but everyone I've talked to call them junk, lol. Guess it's just people that dont know how to tune huh?



geeteeohguy said:


> I agree with Bear and some of the others. Quadrajets came on puny little Chevy 283's, 327's and 305's. Once properly overhauled and calibrated for the engine they're being used on, they are bulletproof and work extremely well. One of the best 4 barrel carbs for the street, if not the best. *Welcome to the fourum*!!


I've been here, where you been?


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## BearGFR (Aug 25, 2008)

> Peopleon heresay there probably the best but everyone I've talked to call them junk, lol. Guess it's just people that dont know how to tune huh?


Well, I guess now you just have to decide who you want to believe. You asked for help and people here responded in good faith. I'll tell you this though, I could afford to put any Carb and induction system on my car I wanted to. I care about power and I care about drivability. I'm running an 800 cfm 455 SD qjet. 

Bear


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## Hot_Rod (Feb 10, 2011)

BearGFR said:


> Well, I guess now you just have to decide who you want to believe. You asked for help and people here responded in good faith. I'll tell you this though, I could afford to put any Carb and induction system on my car I wanted to. I care about power and I care about drivability. I'm running an 800 cfm 455 SD qjet.
> 
> Bear


I'm gonna believe those with pontiac's and running them successfully. 
Seems you guys are not having much issue with them performance wise, I was simply saying the guys that say negative about them just dont really know how to tune a carb. Or assuming anyways. :cheers


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## BearGFR (Aug 25, 2008)

Hot_Rod said:


> I'm gonna believe those with pontiac's and running them successfully.


You have chosen...... wisely :cheers



> I was simply saying the guys that say negative about them just dont really know how to tune a carb. Or assuming anyways. :cheers


I betcha $20 against the hole of a rolling do-nut I can tell you which brand "those guys" favor.... :lol:

(Sometimes I just can't bring myself to say the word...  ) 

Bear


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## freethinker (Nov 14, 2009)

qjets are ok for the street and some limited stock class drag racing but to say they are better than the holly is naive. they have design flaws that limit their racing potential. they have only one small needle valve. they have a tiny float bowl.
the proof is in the pudding. you can go to race tracks and see what people are using in classes where there is no carb limit. you will see few to none on the circle tracks and few on drag tracks in pro racing classes.


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## Eric Animal (Oct 28, 2007)

BearGFR said:


> You have chosen...... wisely :cheers
> 
> 
> 
> ...


MMMmmmmmmm......donuts.........!!! Eric


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## JustAl (Mar 20, 2010)

While I realize this is a different approach to the issue, could the problem maybe a fuel delivery? A weak fuel pump or clogging of the fuel pickup "sock" can cause WOT problems not seen at part throttle. While the 326 doesn't require huge quanities of fuel, poor fuel inlet volumes are sometimes a problem even on "smaller" engines...just a thought.


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## geeteeohguy (Feb 2, 2008)

Hot Rod, where have I been? Out to lunch, obviously! Sorry, did NOT notice your post numbers, etc...in a big hurry as usual. From a real world standpoint, I can say I've driven the original Q-jet on my '67 for almost all of the time I've owned the car (28 years and 130,000+ miles. It's been rebuilt 3 times, and is original to the car: just clicked over to 244,000 miles yesterday. It's a great set-up and works very well. The '66 tripower set up I ran for about a year produced more power, but was not "original" , so the stock intake went back on. Good luck with your project.


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## BearGFR (Aug 25, 2008)

Didn't say Qjets were "better" in all cases, I said they have features Holley's don't. :cheers 

Like: 
Dynamic CFM that responds to engine demands that's tunable.
Variable metering that changes over a wider range of operating conditions (primary and secondary metering rods, APT (adjustable part throttle) on some models)
Tunable primary-side air bleed on most.

They also have some limitations:
Max 800 cfm "rated flow capacity"
Small fuel bowl (not usually a problem with a "good" needle/seat/float and fuel supply at the correct volume and pressure).

Holley's have their good points too:
Easy to change jets "at the track".
Larger fuel bowls.
'Simple' and in widespread use (so lots is known about them and there are lots of parts available)
Larger CFM rated capacity available

And their bad points:
Just one carb 'backfire' will usually rupture the power-valve diaphragm.
Harder to set up to get smooth, seamless operation over all operating ranges (part throttle street) especially the transitions between "modes".
Don't have as wide an operating range as a Qjet, so they tend to run "too rich" in some modes and "too lean" in others - and mileage isn't as good.

Yep, you see lots of Holleys at the track because they're easy to work on at the track, part throttle drivability isn't much of a concern, the carbs have a "reputation" (i.e, just because MS Windows has 90% or so of the operating system market out there doesn't mean it's the "best" operating system - it ain't - by a long shot), and setting one up just for drag racing is fairly easy.

There's not a "one size fits all" answer and nether is one carb "always better" than another. The "best" carb for any application is the one that has the best fit to the engine's needs and how the car gets driven.

Them's my idears... and I'm sticking to 'em... 

Bear


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## Rukee (Feb 8, 2007)

I suppose if the needle and seat are adjusted to shallow, that could cause an issue at WOT.


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## jetstang (Nov 5, 2008)

I like Holley's over Qjets and Edelbrocks. Holleys are straight forward and I understand them. Qjets, it's hit or miss, they run great forever, or are off. I don't get them. A pro rebuild could make a bad carb good. Edelbrocks are nice, but don't make the power of a Holley. Most race carbs are Holley based. I'm not against Qjets or Carters, I just think a Holley looks sweeter..


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## Hot_Rod (Feb 10, 2011)

BearGFR said:


> You have chosen...... wisely :cheers
> 
> 
> 
> ...


Well I mean why would I believe someone that doesnt own or know anything about a Pontiac? 


freethinker said:


> qjets are ok for the street and some limited stock class drag racing but to say they are better than the holly is naive. they have design flaws that limit their racing potential. they have only one small needle valve. they have a tiny float bowl.
> the proof is in the pudding. you can go to race tracks and see what people are using in classes where there is no carb limit. you will see few to none on the circle tracks and few on drag tracks in pro racing classes.


My dad races dirt track and they dont allow anything but a Qjet on his class of cars. (Street Stock) 

But I'm sure theres carbs better suited for different things. 


JustAl said:


> While I realize this is a different approach to the issue, could the problem maybe a fuel delivery? A weak fuel pump or clogging of the fuel pickup "sock" can cause WOT problems not seen at part throttle. While the 326 doesn't require huge quanities of fuel, poor fuel inlet volumes are sometimes a problem even on "smaller" engines...just a thought.


Could be, I really havnt jumped into anything with this car just yet. Only thing I've done so far is plugs and fuel cleaner/additive.

I'm in the middle of building my OTHER Pontiac for a DD for now cause face it, 13 mpg isnt gonna cut it and people drive too crazy to take a chance of tearing up my very expensive to repair LeMans, lol.



geeteeohguy said:


> Hot Rod, where have I been? Out to lunch, obviously! Sorry, did NOT notice your post numbers, etc...in a big hurry as usual. From a real world standpoint, I can say I've driven the original Q-jet on my '67 for almost all of the time I've owned the car (28 years and 130,000+ miles. It's been rebuilt 3 times, and is original to the car: just clicked over to 244,000 miles yesterday. It's a great set-up and works very well. The '66 tripower set up I ran for about a year produced more power, but was not "original" , so the stock intake went back on. Good luck with your project.


It's all good mang. Thats a cool story too, hopefully I can own a car and love it and drive it that long. 


BearGFR said:


> Didn't say Qjets were "better" in all cases, I said they have features Holley's don't. :cheers
> 
> Like:
> Dynamic CFM that responds to engine demands that's tunable.
> ...


I know who I'm gonna listen to when it comes to these cars.


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## Hot_Rod (Feb 10, 2011)

So now I'm beginning to smell gas coming from under the hood. My dad seems to think its going to need a rebuild... It does look old, numerous issues so guess I'll get it rebuilt or something.

What you guys think? Still runs ok like there's nothing bad wrong..


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## Hot_Rod (Feb 10, 2011)

The gas fumes is getting worse, I can smell them going down the road.. You can even smell them when the cars sitting. 


EDIT: I figured it out and not a moment too soon.. The hose coming from the fuel pump was rotted out, was leaking bad today when I looked at it. 

I'm very blessed it didnt explode into flames going down the road. It was a bad leak getting worse..  

But on the bright side, I fixed it and now I think its fine now. Even the WOT issue may be resolved. After I tried it out WOT the thing feels like its stuck 1/3 throttle and will do 20 mph on its own. Throttle cable need adjusting or what?


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