jjokrm

Could you guys please tell me what all is involved in changing over to a 4 barrel from a 2 barrel, besides the carb and intake? I need to know what other parts I need to change and or modify, if any at all. Also, any opinions on the best intake and 4 barrel to go with would be awesome.

I've got a 68' cutlass with a rocket 350, bone stock.

Thanks!

M-14

You'll need a throttle bracket, fuel line, & air cleaner housing.
On a mild build, the pre egr 4bbl intakes are good, they nearly match the edelbrock performer in everything except weight.
What carb are gonna run?

MDchanic

Just so you know, you may not realize any significant gain by changing from a 2-bbl to a 4-bbl on an otherwise stock 9.0:1 350.

There has been some debate on this over the years, so if you do make the change, let us know whether it's any faster.

- Eric

69ishHoliday

I'm in process of doing the same thing. I've bought a 1970 OEM intake w/Quadrajet. I'd like to have a quality rebuild done to the carb before installation but am not sure who would be best to use for the rebuild. Any suggestions would be appreciated. - Steven

yankees

I'm dong the conversion in a few weeks if you can wait that long. I'm using an Edelbrock performer with a Holley 3310 Vac Secondaries carb. I purchased the following for the conversion. I already have the Holley and Performer intake and an Ford 5.0 Dual Snorkle Air Cleaner. Only doing this for this summer as the fall project will be a complete drivetrain overhaul


Mr. Gasket Ultra-Seal III Intake Manifold Gaskets 4694G
Fel-Pro Water Neck Gaskets 35130
Holley Throttle Cable Brackets 20-88
Summit Racing® Carburetor Gaskets SUM-G1417
Trans-Dapt Performance Fuel Lines 2198
AED Fuel Pressure Gauges 6100
Edelbrock Intake Manifold Bolt Kits 8514

jjokrm

I planned on a re-furb'ed Edelbrock or stock Q-Jet.

charlie_hustle

I changed my 72 from dual jet to quadrajet a couple years ago. I added dual exhaust around the same time and it definitely made a difference (factory rated the four barrel as only 20hp more than 2 barrel in '72). You might not feel an improvement from all the extra air and fuel if the new carb isnt set up as well as the origibal two barrel. I used the turkey tray style gasket (but I ditched the molded rubber front and rear seals for rtv), a generic adjustable throttle bracket, fuel line,and I refurbished an original air cleaner. If you use an aftermarket manifold, you may need to buy new bolts as well. I went with the edelbrock performer over a cast iron manifold, mostly for weight. I did it by myself and even an aluminum manifold gets very heavy when you are trying to precisely locate it while hunched over the engine. Plus, there's less weight up front for the small block to push around, not that im racing anybody. I painted the manifold, bolts, vacuum plugs with gold high temp. I couldnt be happier with the way it turned out. Go for it! Just give yourself enough time to label things (vacuum lines, wires, etc), take photos, etc, so youll know everything went back together right.

jjokrm

Interesting to know. Now I don't know if I want to go through the expense and labor

I don't plan on keeping the car forever. I just wanted to make some changes for when I decide to sell it in the future. I just thought a 4 barrel would potentially attract more buyers than a 2 barrel. I'm not looking to hop this thing up too much (will focus that effort and money on what I really want, either a late 60's Camaro/Chevelle or a new ZL1).

Thanks for the knowledge though. Here I thought it would add a significant gain I may still do it though, we'll see.

jjokrm

Thanks! I appreciate the response. Like I said earlier, it's still up in the air if I'll do the swap or not.

droptopron

That won't win you many friend on an Olds site

For resale I think its def worth the effort & having those secondaries kick open will make it funner to drive even if its smoke & mirrors. For what you wnat to do I'd check the for sale section or post a parts wanted ad for a used non-egr intake & carb, but I'd have the carb rebuilt before you install it.

I had my Edelbrock 1910 Quadrjet rebuilt by these guys and i was pleased with the price & service.
http://www.everyday-performance.com/

jjokrm

It's just a thought, nothing set in stone I'm not trying to knock the Olds scene. I love my 68' cutlass. I've just always wanted a late 60's Camaro or Chevelle, that's all

oldcutlass

I would do the 4V change, it may not run much better but it has much more wow factor. If you run a quadrajet there's nothing that sounds like it when you push the fun pedal down.

As far as your aspirations of a Camaro or Chevelle, why everyone has one of those. However I do understand about driving what you like.

Octania

How about an NOS carb?
I know where to get one that is numbered for 1967 V8, I think it has the choke style you need, or if the later round housing, easy convert to electric. Your choice of intake will affect what type of choke you end up with.

Looking at $400 delivered in the contiguous USA 48, I think. Nothing worn out at all. Correct finish.

jjokrm

Thanks, but I'm not going to do anything just yet. I've got some other stuff I need to do to the car first. I appreciate it though.

jag1886

I agree, I had a 68 many years ago and found that a Holley 500 2BBL carb on the stock manifold was way quicker than an Ebrock with a 600. This was on a stock engine with only headers. There is an adapter plate built for this conversion, your intake bores are the same size as the 500 so there is no choke down in size and it's a very simple job from what I remember.

Jedidiah

Sparky's Carburetor Service. He rebuilt my Quadrajet and did an awesome job.

69ishHoliday

Thank you for the recommendation! I certainly want the rebuild by someone that specializes in Quadrajets. His web-site was easy to find. - Steven

jjokrm

I can wait. Post up pics when your done!

The Roadmaster

Kindly allow for disappointment. I did this changeover on a Pontiac 326 in 1971 to my 67 Tempest Custom. Changed the stock 2bbl Rochester carb to the Rochester Quadrajet. New dual exhaust system was incorporated at the time and those Ultra-Cool Thrush mufflers (a lot of racket)

It made a lot more noise when the secondaries opened but as for performance, nothing to write home about. In fact, at higher RPM's the valve train floated out on me. (stiffer springs solved the issue)

Pontiac made an HO for the 326 and their OHC 6 Sprint Firebird packages, both sporting the Rochester Quad. Different heads and cam setup for the HO.

For performance value ($$$), I'd go with the ignition system first.

Now, I have a question for you ... why would you ever consider purposely deceiving someone with a faux 350 quad? C'mon Man!

69ishHoliday

So when you switched your Pontiac 326 2-Barrel to a faux 326 quad did you fool anybody???

My 2-Barrel is overdue for a rebuild and in an effort to put more air in, more air out, I'm putting on the quadra-jet and a set of Hooker Headers, also going on is an extra set of number 5 heads with competition springs that have been milled some too if that's all okay. It is my car.

freds cutty

I just got done doing this about a month ago Edelbrock intake and 650 carb have to say yes it was worth it. Hit the fun pedal and it really makes a diff. Only real thing is get your timing right and you may have to get the calibration kit its actually easy if you have any mechanical ability. Believe it or not you may actually see gas mileage go up if you can keep your foot out of it.

69ishHoliday

Good, I'm thinking it will be worthwhile making upgrades. I've owned a couple of 69 Camaro's that had Q-Jets (one 396 & one 350) and they weren't terrible. My decked and balanced 302 68 Z28 made them seem like golf cars as would many other performance engines from any of the big three. Modest improvement is all I can expect from a rocket 350 without starting from the beginning with a forged crank, decked block, big valves, etc, etc. If going there I think I'd have to follow the "no replacement for displacement" and start with the 455. - Steven

The Roadmaster

Actually, I wasn't responding to your post, rather JJokrm's :

I don't plan on keeping the car forever. I just wanted to make some changes for when I decide to sell it in the future. I just thought a 4 barrel would potentially attract more buyers than a 2 barrel.

To answer your question though ... No, it fooled no one. It wasn't supposed to.

And yes, it is your car. Do what you want with it.

jjokrm

Thanks for enlightening me about your own experience in doing the 2 to 4-barrel swap. It's good to get feedback from everyone as it helps guys like me make a decision on if I want to take on this project.

I've already planned and bought everything to convert from points to electronic ignition; thanks for the heads-up though.

As for "purposely deceiving someone with a faux 350 quad", I'm not purposely trying to deceive anyone. I am however purposely trying to modify my car however the way I want. I guess everyone who has ever modified their car from "stock" is purposely trying to deceive someone.........WTF? Last I heard, this was called "Modifying" your car!!!!!

The Roadmaster

Referencing your original quote:

"I just wanted to make some changes for when I decide to sell it in the future. I just thought a 4 barrel would potentially attract more buyers than a 2 barrel."

That reads differently than 'modding it your way'. Perhaps not intended but that's how it appeared.

Regardless, have fun with your project.

Beenz

I am doing this swap right now . I had a bone stock 69 350 with a rochester 2bbl . so far ive added the edelbrock 2711 preformer intake , all new intake bolts ,new valley pan ,went rtv on the front and back ,edelbrock 1406 electric choke 650cfm carb ,im right at the end of this conversion but im hung up with the little crap to get it complete such as , threaded plugs for open holes new temp sending unit ,need an air cleaner , and finding the right parts to hook up the new carb to the stock pump has been annoying . I bought a used intake for 50 bucks ,which took a year to find a used one btw especially the 2711. anyway i had it cleaned for 10 bucks acid etch primer then Vht aluminum high heat paint followed by a vht high heat clear coat ,looks brand new .I bought the new carb for 100 bucks brand new off of offer up .I re did the altenator brackets the same as the intake as well as the water neck ,looks great . ill have more info,pics and results soon . check the pics of the intake oh yea so for this swap ive needed here goes

intake and intake bolts ,carb and studs, valley pan gasket ,black rtv,blue thread locker, Teflon tape ,ill need a throttle cable bracket(im fabricating one) adapter for the 5/16 outlet on the fuel pump to a 3/8 inlet on fuel filter (you have to run an inline filter )plugs for the extra spaces on intake i had to get a 3/8 heater hose barbed fitting,lots of shop towels , ill need to change the oil possibly twice from any debris from changing the intake ,torque wrench up to 50 pounds feet ,3 feet of 3/8 fuel line ,fuel filter ,oh and i bought the edelbrock fuel line kit that reroutes the fuel line under the choke ,but it wont clear the manifold it seems ,so im getting a .5in 4 hole carb spacer too ,oh yes and a gallon of antifreeze ....more to come im sure

svnt442

That 1406 is 600 cfm.

Nice work.

Beenz

[QUOTE=svnt442;968736]That 1406 is 600 cfm.

Thanks . ill be posting more of the completed project

olds 307 and 403

I would have used a different carb. Nearly every shitty running car on here involves an Edelbrock carb. The Street Demon 625 cfm is a much better carb.

Beenz

yea ive heard good and bad about these carbs but ill use it until i do the cam ,timing,and pully system which will be sooner than later also what do you like about the speed demon ?

oldcutlass

For what it is the Edelbrock is not a bad carb. I think 80% of carb problems on relatively stock engines are ignition related on here.

olds 307 and 403

The AFB design is OK but is dated even as carbs go. There seems to be something gone wrong in Edelbrock's execution. The Street Demon is heavily based on the AFB/AVS replacement, the Thermoquad. Except it is an all new 3 barrel casting to fit on square and spreadbore manifolds. Also gone is the o rings between bodies which quite often leaked, pretty sure that went on the 800 TQ I had along with the Bakelite Phenolic body which is now Aerospace polymer but aluminum is also an option. Also an improved choke and you can even get a tps for them to work with electronic OD transmissions.

Firewalker

The "Street Demon" is pretty much the cat's meow when it comes to cheap and easy, and versatile. It is a cross between the thermoquad, Holley 3 barrel, and the Thunder series. Designed by the guy who did the AFBs, the AVS, and Thermoquad carbs and most likely built by Carter, for Holley. Many of the parts are all the same, such as floats, needle and seats, accel pump, probably primary rods. The tiny C clips here and there found on it I replaced with larger hair pin clips I also like brass floats better than the leaking over time later nitrophyl floats, so I got the new brass floats, for a thermoquad. AFB and AVS might be the same.

RetroRanger

I've used two different ebrock carbs on two different engines w no problems, idk think they provide the optimum performance but certainly nothing inherently wrong w them. I now have a qjet I'm very happy with

Beenz

ok so all is hooked up except the vacuum hoses ,my engine is 1969 non egr olds 350 and a th400 trans installed in a 79 chevy c10 it had a manual choke 2bbl carb now I have a 4bbl electric choke I have performance stock replacement accel distributor I have an edelbrock 1406 carb need to know what vacuum hose goes where to the carb please here is a pic of it as it was when I got it

svnt442

PCV goes to the large center port. Trans vacuum to the port on the drivers side and the distributor to the port on the passenger side.
You can either plug the port on the rear of the carb, or if you need to, you can run the brake booster to that port if there isn't one on the manifold.

Beenz

thank you , ha i was just figuring it out scowering over threads .but thanks so much for the confirmatiom ,so i have hydra boost brakes so i wont have to use the port on the carb ,correct ??

Beenz

may be a dumb question but i was wodering how important is a throttle cable bracket the stock 2bbl bracket was home made in a few miniutes it wont work for the 4bbl carb im pretty sure i know the answer to this alrwady just need to hear it ha

svnt442

Yeah, don't worry about the brake then if you have the hydraboost. Just make sure that you plug the port in the rear of the baseplate.
If you can make the bracket work, that's fine, but you may need to find a replacement.

Beenz

yea back port is pluged ,yes hoping the bracket works ,should be ez ,th 400 no kick down so hopefully it will be no prob ..hopefully ha