Quadrajet carburetor on a 231ci V6

[SolarGoldRaptor]

Hi,

The original Dualjet from the late 1978 Buick V6 of my Pontiac Firebird Esprit is surely dead, and I've been given a nice Quadrajet from an Oldsmobile 403ci V8.
I'm far from being an expert in mechanics, so I don't know if what I want to do is feasible : can I replace the Djet with the Qjet ? With the right intake of course.
If it is possible, what else will I need to do (adjustments? new parts?).

I know the easiest thing to do to increase the power of my Firebird would be to put a V8 in place of the V6 but I don't like when there is no challenge. My goal is to make it more efficient instead of just increasing power. Plus I'm french and it can be quite difficult to replace an engine by a more powerful (legally speaking).

Merci !

 

[Freddie's Buick]

.....The original Dualjet from the late 1978 Buick V6 of my Pontiac Firebird Esprit is surely dead, and I've been given a nice Quadrajet from an Oldsmobile 403ci V8. I'm far from being an expert in mechanics, so I don't know if what I want to do is feasible : can I replace the Djet with the Qjet ? With the right intake of course. If it is possible, what else will I need to do (adjustments? new parts?).

Do you have a 3.8 V6? If you do, you can get an after-market intake for the Q-jet. They still sell them. Or, you can get a carb adaptor. They sell those too. The easy way out is with a carb adapter.

...
I know the easiest thing to do to increase the power of my Firebird would be to put a V8 in place of the V6 but I don't like when there is no challenge. My goal is to make it more efficient instead of just increasing power. Plus I'm french and it can be quite difficult to replace an engine by a more powerful (legally speaking)..... V6Merci !

With the V6 it's not that it is difficult, it's more like What Carol Shelby once said, 'There is no replacement for displacement'. That is......if the 3.8 is not turbo powered. :biggrin:

 

[SolarGoldRaptor]

Hey thanks for your reply

I do have a 3.8L V6 (231ci), the base engine for the base Firebird and Firebird Esprit models at the time. I'm not sure my motor is "even-fire" as the car was built in October or November 1978.

I've seen Edelbrock intakes but they say that it won't work for pre-1979 engines...plus I think it deletes the EGR (I don't what it implies). Also, according from the picture it looks to be higher than the original intake manifold.
Sorry, I can't put a link as I have less than 4 posts...

Would it be a good buy ?

 

[Freddie's Buick]

....I've seen Edelbrock intakes but they say that it won't work for pre-1979 engines...plus I think it deletes the EGR (I don't what it implies). Also, according from the picture it looks to be higher than the original intake manifold.....Would it be a good buy ?

It may not be a good buy in your case. The EGR is not absolutely nessacary, but it depends. If you have a limited knowledge of this engine then stick to OEM. (I believe if it ain't broke and it works....leave it alone).

As for the intake, it relates to the cylinder heads I believe. It may not fit. And yes, it does sit higher than the OEM intake.

Like I wrote, the adapter may be the easier way out. No extensive modification required that are too involved. But the adapter too will sit higher. You'll have to get an after-market airfilter canister. Edelbrock sells it. It sits only 2.50 Inches high with the filter.

 

[b4black]

1978 would be even fire. It has the low ports heads, which is why the intake won't match. In 1979, they went to high port heads and these could be swapped onto your 1978 motor.

There were low port 4-barrel intakes available. Offenhauser might have been one of them.

 

[Junior Samples]

Although the dueljet is toast you say, going through the hassle of sticking the quad on might not be worth the effort and your results might be poor

giving your motor a volumetric efficiency of 100% which should really be about 65% but for example..

times your rpm i put that about 5000, ive come up with a demand of about 334cfm

id keep the duel jet and send it off to SMI carb's out of long beach cali

you can ask shawn about rejetting options for it, i know the med to heavy acceleration suffers from leanness

hope it helps

mike

 

[SolarGoldRaptor]

Allright, that's what I feared. So the QJet, even if ajusted properly would make the engine run too rich ?

The problem with the Dualjet is that the car stayed outside without a hood for about six months. The carb was full of water, and it was totally stuck. Even with plenty of WD40, the rod that holds the two throttle plates bent and I can't figure out how to remove it. I guess I should replace the lower throttle body.

 

[Junior Samples]

Les conditions de cfm pour des 403 sont presque doubles de votre moteur et sans savoir des nombres du carburateur et voyagent en jet des tailles que je devrais dire que si vous installiez le carburateur sur votre voiture tomberait sur son visage à la commande de puissance de partie.

 

[b4black]

Buick V6's came stock with Quadrajets. They will work. This was on the 4.1L. Slightly bigger than a 3.8, but many, many people have bolted on the 4.1L intake and carb succesfully. There are many aftermarket 4-barrel intakes available. It will work well.

 

[Junior Samples]

Cool beans, find intake and away you go.

Being a chevy guy and new on here im learning more and more everyday. Although the carb will only meter what the engine demands i kinda thought it a little much for the 231.

 

[Freddie's Buick]

.....giving your motor a volumetric efficiency of 100% which should really be about 65% but for example..times your rpm i put that about 5000, ive come up with a demand of about 334cfm.....i

What?

SolarGoldRaptor, if you have the Q-jet you'll be just fine.

 

[Junior Samples]

He said his buddy gave him a quad from a 403 correct?

Ok with out numbers who can say what jets are in it? a 66? up to 78..i dont know.... i could prolly say its smog set up but still i havent the foggiest whats in it.
Main metering rods single or double taper?..does it matter?
What secondary metering rods are in it? a CC? a BL?

I had a 403 in a buick estate wagon and it ran like hell

Take this number x that number x volumetric efficiency which is how well the engine breathes..if its N/A with clogged airfilter then its prolly inhaling like someone from michigan who goes down to central Florida in Aug with 110% dewpoint.
So if you put your VE at 100% that is not being honest so to be realistic i put it at 65 to 75%

How much air can that motor effectivly use? (N/A)
you take displacement X rpm X your VE devided by errrrr 3456 er somthing like that to get your CFM

Them dualjets are from 220 somthin to around 300 cfm

That quad for the 403 has to be at the least ?cfm

He dosent have an ecm/sensors to meter everythin and no turbo to cram air in so all the figuring out is done the hebrew way.

IM not debating anyone if the carb will work or not IM just going by a N/A formula
SO the carb will work.. but trying to find 4.1 intake in FRANCE!? then the linkage bracket etc etc.


id just send the thing out and get it rebuilt or he can send it to me but SMI are the whip and 4 week turn around with expert knowledge..me im just a schmo that can make things run...a little

 

[SolarGoldRaptor]

Well, I have to admit that I didn't know it was so complicated to adjust a carburetor...
Anyway, here are the numbers I found on the carb :
17058274
2107 BAP
17053753

There is also this round thing that shows the date it's been built...there are nine dots so I guess it means September but the number in the middle might be a 6 as well as a 9.

It seems to have been remanufactured as there is a sticker which says so, and some parts have been painted in black.
It looks like te EGR valve has been welded on my intake and the screws won't budge...I hope it's just an illusion because it quite rusty and
dirty so if I want to soda blast it I'd prefer removing everything.

I don't mind ordering parts from the US when needed or when it can be cheaper.

 

[Junior Samples]

The adjustment on the carb is not hard. The hard part is getting one one to work correctly to fit your application.

GM didnt just have a bin full of Q-jets for every motor and one size fits all.

My whole point in this thread was this... the carb that was givin to you would bolt on with the 4.1 intake as described by some other posts, yes it would provide fuel to the motor to run, would the car idle?..yes would it go into gear and go down the road?..yes

Now how good would it work when its jetted for a 403 cubic inch to provide proper metering for your 231 NA motor? well you would have no shortage of fuel hows that...LOL

Do you know the model number of the dual jet on your car now? as in model 200 M2MC or model 210 which has 1-7/32throttle bores?

Id like to help but i really dont know what else to say..if your set on putting that carb on then find an after market intake, you'll need another throttle cable bracket, tkae your time and make sure your gasket mating surface is clean, dont gorilla torque your bolts, hook it up and go like hell:biggrin:

Mike

 

[SolarGoldRaptor]

GM didnt just have a bin full of Q-jets for every motor and one size fits all.

That's what I thought at the beginning

The Dualjet is a 210.

Thanks for your answers. I think I'll stick with the Dualjet for the moment, and see if I can find find a new lower throttle body or a complete carburator.

 

[b4black]

-jet.

That quad for the 403 has to be at the least ?cfm

750 cfm. All Q-jets are 750, with the exception of a few that are 800 cfm. The 78-80 turbo 3.8 is one of the few with a 800 cfm. The little 4.1L V6 used a 750 cfm carb.

 

[unboostedV6]

FYI... A bone stock, unmolested 750 Q-jet from a '76 Buick 350 LeSabre worked very well on a mild cammed 4.1... GB

 

[Junior Samples]

the question mark thing was a theme i had going, I signed up to this site to get help on this buhog and somehow wound up on this thread.

i do understand a little having repaired a few lawnmowers
I mean yes carbs are flow rated at wot and the cfm is amount of airflow that causes a specified preesure drop correct? and rochester rate at a drop of 1.5 inches so the bigger carb the lower drop but what is going on at the low end of the flow curve? will it be able to meter correctly at low airflows? and will it work well at the the speed at which he will be using most?

he did say his was an NA motor but you guys ...you all have had way more experience at these 3.8's or 4.1's then I

I just didnt want the poor guy to go through all the hassle
but i did notice that he wrote that his hood was off and it rained alot in his carb..hmmmmmm so if it rains in the carb where does it go after the carb?....hmmmmmmm

 

[charlief1]

Solar gold raptor. The 78 3.8 has low port heads. The only intakes that might fit are the Kenny-Bell 4bbl or the Holly. I used to run a N/A 3.8 with a 4bbl but I made sure to use high port heads and a 4.1 intake. You can port the sh_t out of the heads and intake and use a cam to make a suprising amount of power. I ran a H-body in SCCA street modified/ super street modified and twisted the chasis, threw a ring out the diff cover, broke a tranny case.

 

[SolarGoldRaptor]

Hi Charlief. Good to hear someone who tried it !

Actuallly, my Firebird is a 1979 model but it was built on the first week of November of 1978. Does it change anything ? How can I recognize hi port heads ?

Here are pictures of my engine, yeah it's dirty as hell !