hello,
Do I rebuild what I got or buy the right carb already done from a builder?
I have a '68, 427, 4spd car with a 69 350/350 auto quadrajet.
I know the 68 carbs are rediculous in price.
My thoughts are do I rebuld this carb which is for an auto and wrong to begin with or do I spend the money for a properly rebuilt 4spd quadrajet carb?
I cleaned the carb today with carb cleaner and took for a ride. I came home and fuel leaked all over the intake manifold from the accelerator pump on top of carb. It looks like it was pouring out as every valley in the manifold was full to the top with fuel.
I'm leaning to obtaining the right carb w/ right throttle linkage as the auto linkage has been bent outward by previous owner to clear an intake manifold bolt head. Kick down extension hits bolt during accelleration.
Because the carb is in need of rebuild I figured it may need the plugs sealed, throttle linkage to body may need bushings installed etc..
and the linkage is still wrong and needs to remain bent to work.
I'd gladly trade carb & $ for a rebuilt manual version.
Who is a reputable rebuilder?
Thanks
Marshal

 

There isn't a lot of difference between the '69 carb and the one that came on the car originally. The carb for the 427 w/manual trans should have #71 jets, #47 primary rods, and AX secondary rods. If you can locate those original parts, great. If not, Edelbrock sells a portion of those part sizes; the closest available approximation to those parts is Edelbrock #1946 primary rods (.045"), #1969 jets (.069"), and a CK secondary rod (CE could work, also).

That gets you close with the rods/jets, but you would also need to do something about the differences between the auto/manual hardware. It would be best to buy Cliff Ruggle's booklet on "How to Rebuild and Modify Rochester Quadrajet Carburetors" (about $20 at some Forum vendors or on Amazon.com) and make adjustments/modifications required to optimize the '69 carb for your engine.

That's what I would do, as I doubt that any aftermarket rebuilt unit would be as good a match for the original as that.

Good luck.

 

7T1Vette,
thanks for the reply. The PN's are a big help. I have no idea what's in it now as it was orig. made for 350/350 auto.
Can I replace the throttle linkage plate where the accelerator cable attaches? If I could get the manual part it would be worth doing the makeover. It seems like an effort in futility if the linkage plate has to remain bent outwards to clear the manifold mounting bolt after rebuillding as it looks ghetto.
Thanks
Marshal

 

This helps:

 

7T1 Has a lot of good info here, but there is more to getting the carb to meter correctly than rods and jets. The Quadrajet has a lot of metering parameters that are not easily adjusted. Each stock unit is set up to meter corretly using all of the metering points as an ensemble. For that reason, I would recommend rebuilding the carb as is, then tune it for your engine from there. Putting the manual rods/ jets in the auto carb could result in a poorly functioning unit.

As far as the linkage, it is usually pretty easy to get an auto carb to work for a manual. You should be able to figure it out and if you don't we will help.

The gas leak is probably where the fuel line goes into the carb. Be careful here, getting it tight can be tricky if you have not done it before. Be careful not to strip/ crossthread anything.

God bless, Sensei

 

The correct rods and jets for the carb for his engine (those are the same pieces for '68 427 std and hi-perf engines with manual tranny), a good rebuild kit, a new brass float (dunked in water to assure no leaks into the float), and the Cliff Ruggles booklet are all someone needs to rebuild their Q-jet carb. Yes, there will be other things to do for a proper rebuild....and those will be detailed in Ruggles' book.

As for the manual linkage, you need to check the internet for a '68-72 Q-jet throttle plate for a manual tranny or pick one up at a parts swap meet somewhere. It can replace the plate/linkage set on the carb you have. If necessary, 'tweaks' can be made to match the original plate (per Cliff's instructions).

If the OP can find a manual tranny plate/linkage and the needed rods/jets, I see no reason why the above suggestions would not put that '69 carb back to good condition for his '68 engine.

 

7T1, I respect your knowledge and am not saying your info is bad. But if you look at the Q-jet's many configurations, often very similar engines had very different rod/ jet combinations. Why? The other metering parameters of the carb (bypass air, various bleeds and metering passages) were different and made to give the desired results with a specific rod/ jet combination. You cannot simply take two different Q-jet cores, put the same rods/ jets in them and expect them to be the same. It's not that simple. The best way to go is to start with the original set up (how the carb came from the factory) and tune from there.

God bless, Sensei

 

Ok the jury is still out on this one
Do I tune and replace throttle plate as 7T1Vette described which is what I wanted to hear?
Or do I find the core which was set up orig for a 427 and rebuild it?
I'm listening to both arguments constructively just not sure which is better for my current situation?
Thanks,
Marshal

 

Why don't you post a pic of the linkage interference and go from there.
The 400 tranny is electric kickdown, so an automatic carb should not be an issue.
Number off the carb may be of help too.

 

Whatever parts you have to hustle do it yourself, If you have basic skills and you follow the recipe in Cliffs book and take your time you will end up with a better carburetor than 98% of the builders in this country can build.

The biggest improvements come from rebushing the throttle shafts and re-sizing the idle circuits. When you have these carburetors properly prepared and the ignition is healthy you will never have to touch the accelerator when you start it.

it is all about the calibration of the carb


This is all detailed in Cliffs book, without access to a dyno follow it to the letter and you will be way better than average


Carb works in this order

1. idle circuit
2. transition from idle to primary side
3. transition from primay side to secondary side
4. secondary side

it's best if you tune it in that order ;kind of a methodical process of elimination



Regardless of which car it came off of you can calibrate it for your application

A Q-jet when properly prepared will make more horsepower than most professional Holley builders can deliver and won't burn your eyes when it idles :-)

Do not throw away the vacuum pot on the secondaries ( most guys do)



The only draw backs to this carburetor is it's small fuel bowl size. If you are going to run your car hard ( high RPM for extended time) with the stock fuel system it will run the fuel bowl low enough to run it lean. If you are drag racing and do not have a properly prepared fuel system you will bust you nose on the steering wheel when you leave the line.

If you do decide to build it and have any question I will be glad to answer any questions you may have.


Believe only half of what you read on the internet

and do not buy into the rigamoro of the latest air cleaner and spacer and on and on

BLAH BLAH BLAH

I could go on for days

I have dynoed all that CRAP

All Ima say is the Factory got a few things right

If you decide to buy one do not buy a remanned carb from a parts house the calibration on them are usually not even close and in most instances they ruin the core


Cliff Ruggles will have the correct carb but will get a premium price for it ( he is a great guy by the way)

My advice is to hunt a core that works or the linkage or parts or whatever and do it yourself you will be glad you did

Best Regards, Jim

 

So true. I read somewhere on here something to the effect that there are no shortages of experts on the internet, trouble is deciding which one to believe.

As a mechanic that got his ticket in the 70's I have worked on literally hundreds of those things. Starting in the early to mid 70's model year the biggest issue was lean idle. Idle circuits were so restricted that you would break the limiter caps off the mixture screws and turn them out so far they would fall out and you still couldn't get a "nice' idle. Of course this made them super susceptible to vacuum leaks around throttle shafts and anything else that made the lean condition worse. Other than that a nice easy carb to work on.

I always wonder about people swapping out their q's for old AFB's (edelbrock) carbs. All about marketing. Take an old design carb that GM gave up on in the 60's and repackage it under the name of a hot aftermarket seller. Genius.

Steve g

 

No doubt


I hate to see people taken advantage of

Like you I went to the school of show me, I have read practically every carburetor book and have read every book on the Q-Jet

When I started dynoing my stuff I was amazed at how little the Internet Gurus really knew and most people writing the articles. I guess every body has a place... and most folks aren't the worse for it, just kinda sticks in my craw though.

I ordered a spacer from a very reputable aftermarket company that looked like it was worth 50 hp

Much to my chegrin it lost about 15

The next day I get on the phone and call and ask them what kind of number they made with it in their Dyno testing...

Long pause with complete silence....

then uuhh well we have never dyno tested it.

I was speechless and $75.00 poorer After I pressed them their answer was; well on the computer modeling we did with it showed swiirl improvenment derrr... Unbeliveable!!!

I found out if you build a better racing piece you never have to advertise it. The guys you want running your stuff will always find you.

I'll put my soap box up for now

on to your comment, you are correct

The idle circuits were very anemic to pass emissions

Made the cars hard to start and lazy off idle...

Oh and for the record the AFB's won't touch the Q-jets for Horsepower

Best Regards, Jim

 

Take what ya got apart, clean real good with carb cleaner, get a kit and install all the gaskets and a new float and adjust it put it all back together, adjust the mixture screws and idle and be driving before supper.
Its no big deal to do, if it takes more than a couple of hours from beginning to end your doing something wrong.

 

Thanks,
I ordered Cliff's book as suggested
And I will dive in.
Stand by for me guys
Marshal

 

Marshal135,
Get that Doug Roe book mentioned above also. Cliff's book is real good explaining some things you won't need to do for your carb (high performance mods). It kinda lacks on the basic rebuild stuff. I think you should have both, and use them to complement one another. Where one is unclear, the other will make up for it.

 

When I decided to use a Quadrajet, I knew I wanted to rebuild it myself. Cliff's book will convince you of this also. Where Cliff's book was unclear to me, I was able to call him or reach out to the forum on his site to get the answers.

I also went with Cliff for the parts. Tell him your set up and specs and he can get you the parts to make the carb you have work well.

For example, on my carb he had me press in smaller air bleeds for both primary and idle circuits and replaced the rods and jets with different sizes. The rods were custom lathed by him with teeny tiny power tips.

Best of luck to you

 

Glad to hear you decided to do it your self more people in this world need to ask questions and find out more things for themselves.

Doing it yourself takes the mystery out of carb rebuilding and from now on no matter what carb you you rebuild you will realize that they all have the same circuits as I mentioned before.

I will also be glad to answer any questions may have for what ever it's worth.

a twenty minute conversation will clear up alot I no longer rebuild carbs I gave my business to a friend when my wife was diagnosed with cancer. It was a hobby to start with that turned in to an obsession. Any way thanks be to GOD she is healthy and as pretty as ever and forever tries to keep me in line.


This is not lip service and I very humbly say I have two UMP national dirt championships to my credit and scores of wins before I got out.


PM me if you would like to talk, otherwise Good luck you are the better for your decision!

Best Regards and Happy Thanksgiving, Jim

 

I really don't agree or believe that above statement.
How much money would that take to achieve that goal.
The race track is full of what works and its not a quadrajet.

 

I have thought of alot of ways to respond to this, the following I feel is the most consrtuctive being you flat out called me a liar.

I have nothing to gain by stating the things I do.

Whether you believe me or not, I could care less... I don't build carburetors anymore I just got tired of dealing with racers that did not want to work hard enough to win.

Only a true RACER will understand the preceeding statement. Guys that show up at the track and run their stuff and never win are no worse for the wear. As I stated in an earlier post everybody has a place. It's the Pareto Principle in action.

Occasionly I respond to things on here trying to help out the average guy with the things I learned.

It's a biblical thing;
Luke 6:38
New International Version (NIV)

38 Give, and it will be given to you. A good measure, pressed down, shaken together and running over, will be poured into your lap. For with the measure you use, it will be measured to you.”

"Just for the record it works the same with knowlegde"

Sorry If I digressed a bit I guess I am practicing getting older, anyway...



The world is full of people that doubt things. I am one of them too, some things you just need to find out for yourself, I did. What I stated is what I achieved and tested on the dyno myself against the major carb builders in this country. (if you have nothing to measure yourself against you will never get any better). If you can measure though, you can improve it...

These were back to back test on the same dyno mule under controlled conditions on a a Superflo 902 Dyno. Not what someone told me or something I heard about that was purveyed as gospel from some third party or internet Guru.

I probably should have prefaced my statements with the following statement:

The Quadrajet was not designed to be raced, it was designed to get the average Joe down the highway with decent gas mileage.

In it's stock form you are correct, it will not out perform a Holley carburetor.

In it's modified form it will, In the confines of it's CFM capability. As long as you keep the fuel bowl full (another challenge all together)

The modifications I am talking about were better than two years of constant Dyno testing and racing every weekend. The class we raced, we had to run these carbs. You learn alot if you are willing to work hard and hate to lose... I learned alot of ways on how not to build carburetors before I got it right.

Sorry if you feel like I need to prove something to you... I am good with with the things I know to be fact...


Besides ignorance is bliss.


Oh, if It makes you feel any better the primay jets I used in all my carburetors were Holley's, "Precision 68's" to be exact.

Best Regards, Jim

 

Hi Jim,

Haven't run across you on the forum before.

It's also nice to see another person who's had similiar experiences regarding Q-jets. I can't recall all the times I've been poo-poo'd by people when I suggest they use a Q-jet over a Holley. Crisper throttle response, better mileage, and more overall horsepower.

I haven't played with testing carbs on a dyno in about 20 years, but one instance that does come to mind was comparing a Holley 750 to a qjet on a 400 SBC. In this case, the Holley did best the qjet by something like 10 peak hp, BUT the qjet beat it soundly in mid-range by something like 35 hp. It was pretty eye opening.