blakkmaxx

Hello gang. I am going to replace my 390 hp. 68 427 motor quadrajet and factory aluminum intake with a holley carb and intake that will fit.
it is a 4 speed car with air. I want something that will start and run every day. Thanks in the advance.

JimLentz

Have the quadrajet rebuilt.

commander_47

I"m a big fan of the Street Avenger series for street cars DD.

You could probably use the 670cfm. I opted for the 770 on my big block 454. My motor is modified, however, with rectangular port aluminum heads and such.

http://www.summitracing.com/parts/hl...FYQvgQodzxgAWQ

You can also check the factory refurb store for good deals. These all come with factory warranties and great savings.

http://stores.ebay.com/Holley-Perfor...fsub=885534016

I am currently using a Wieand intake on my BB, but it is really hard to beat the performer series for street car daily driver type.

Edelbrock says none of these will fit under a vette hood, but I know the performer does, and I believe a Performer RPM will with a drop base air cleaner.

There are plenty of threads in the forum dealing with the issue.

You won't regret the move.

Easy Mike

C3_ERROR

In the end it's just a rebuilt quadrajunk. I say replace it with a better carb you won't be worried about a few years from now.

LeMans Pete

Unfortunately, it is opinions such as these that convince others that they need to replace their carburetor. These opinions are typically derived from poor performance that most likely originated with a timing issue, yet blamed on the "quadrajunk."

I agree with others: Have the quadrajet rebuilt by a professional (like Lars) if you have diagnosed the carburetor as your starting issue. To maintain fitment, stick with the stock intake manifold.

C3_ERROR

My "opinion" is based off having a ton of cars with a quadrajunk on it. They suck for performance, they need to be rebuilt more often then any other carb I have owned. They are cheap production carb that have flooded out more motors for me then any other.

69Vett

big block aluminum intake that fits under the hood, I would keep that intake and not replace, slap on a new Holley spreadbore carb.
very few intakes will fit under stock hood...keep that Aluminum OEM intake.

LeMans Pete

Your "opinion" seems to suggest that perhaps you do not know how to properly tune/set up a quadrajet.

C3_ERROR

Yes my tuning and setting up a quadrajunk is what caused the seals to leak and the floats to stick on multiple cars that I never touched the carb.

I'm not the one who came up with the word "quatrajunk". It's been around LONG before I was into cars. My opinion is based on my experience with them but the majority opinion is the same. In fact it seems like the OP has a similar opinion based off his comment.

DABall

I agree with 69Vett, put a Holley spreadbore on your original intake and you are good to go. I did that on my 70 LS5 and there were no issues with the stock hood and air cleaner. It comes with an electric choke and mechanical tach that fits right into your original tach setup.

commander_47

Like me, you have to kind of learn to ignore the Q junk harpies.

Everytime someone mentions OTQ (other than Q-junk) they have apoplexy and start accusing us all of being ignorant and dumb about the supposed "benefits" of the junk.

The OP asked about combinations OTQ that will work with his BB and now we have to help him out.

A spreadbore Holley with the stock aluminum intake is one way. But that still limits you to spreadbore. Those stock aluminum manifolds are nice to have.

If the op decides to go square bore, he will have to change the manifold. Spreadbore really limits your choices.

I believe the straight performer will fit. But the best way is to check the Edelbrock page for all the specs on the manifold.

Then check the Holley page. All the specs are there. You can then simply use some small blocks of wood to mock up your setup, a little clay to figure the correct drop base air cleaner to use.

Stock the air cleaner is 3 inches. With a drop base and two inch air cleaner I believe the Performer RPM will fit.

But make sure you check it. It's easy to do and a good way to spend an afternoon NOT mowing the lawn.

lars

These threads still crack me up...

As you guys know, I rebuild a crap-load of carbs - Q-Jets, Holleys, and the Holley clones: about a 50/50 split on Q-Jets and Holleys come through my workshop. I get exactly the same complaint condition on both carbs:

This (Q-Jet/Holley) is a piece of junk!
This (Q-Jet/Holley) floods out and won't run!
This (Q-Jet/Holley) spews fuel out the vents!
I've tried everything with this (Q-Jet/Holley), and I can't get it tuned!
My buddy told me to get rid of this (Q-Jet/Holley) and get a (opposite Q-Jet/Holley)!

It doesn't matter which carb you have - you can have bad experiences with either one - I can assure you it's a true 50/50 split - I've seen it for 40 years now. Any carb can have a jammed float, a bad setup, a poor rebuild, a hack job Bubba mod, and be impossible to work with - I see it equally on both Q-Jets and Holleys - no difference. Either carb, of similar cfm flow capacity, will perform identical to the other once correctly set up, so run whatever carb you're comfortable with tuning.

If you want to run a Holley on a '68, get the '66-'67 Vette aluminum Holley intake and run whatever Holley you want. I like the Ultra-Series carbs if you prefer the Holley line. I'm also very impressed with the new QuickFuel carbs - they are set up very well from the factory, and they have good quality control. If you want to stay with the Q-Jet, the stock carb can be rebuilt and set up to run just fine.

Good seeing you posting again, Commando!

Lars

Johns66

Wouldn't the '68 390 hp 427 have oval port heads making the use of a 66-67 aluminium manifold a mis match with their rectangular ports?
What would be a good choice for an aluminum intake for oval port heads running a Holley carb?
Sounds like the best way to go is to have your Qjet done by Lars.



John

SI67

What does the carb have to do with the tach? A Holley spreadbore comes with a tachometer? Were you in a hurry, or am I about to learn something?

Seriously--I'm not sniping. I'm just baffled by the final sentence of your post. I THINK you meant to say something else, but I can't figure out what that is. Something about mechanical SECONDARIES?



Steve

commander_47

I'm still here!

Shhhhhhh, keep it quiet. I agree with your post above.

I still feel the q is inferior. It just isn't made well.

Sticking floats and such are sort of common to all carbs.

The warping of the q body due to overtightening, or the propensity to strip threads and the small float bowl are q specific.

The search for 'rebuildable' cores and such just isn't worth it.

If someone still wants to go q, have at it.

Any Holley out of the box will work fine, easy to get parts for and tune, and basically bullet proof.

jb78L-82

The Qjet is a decent carb when it runs correctly…it is not easy to repair and that is why experts like Lars are around to properly fix them. In my opinion the quadrajet is overly complicated for what a carb needs to do and was GM's attempt to forego mechanical fuel injection in the 60/70/80's by precisely attempting to meter fuel through a carb, a pretty universal one at that. Holley's have their fair share of issues as well but are very easy to rebuild and tune..I have had a 4175 650CFM vacuum secondary Qjet replacement Holley since 1985 on my C3. Just rebuilt it for the first time about 3 years ago…runs like a charm.

Petes73

If someone wants a Porsche would you you question his opinion? It is one choice of many. Carbs are also a choice. As much as you want to carry on about "have it rebuilt by an expert". Many people enjoy doing their own work. I do not have the time or inclination to get a PHD in Quadrajet. At the end of the day even you admit there is little difference. I like Holleys. If you follow simple directions they are easy to set up and easy to tune.

LeMans Pete

Pete, the impression that I received was that the OP felt that a quadrajet couldn't perform consistently on a day to day basis, not that he had a preference for a Holley. I think if he sent the carburetor off to someone like Lars, not only would he has his exact wishes (cranks right up, idles perfectly - assuming ignition is set properly) he would most likely pay less than if he purchased a new carburetor, and possibly another intake. Then throw other modifications required (PCV, choke, air cleaner assembly, throttle cable), there is more of a hassle to switch, with possibly no benefit!

I have rebuilt both Holleys and qjets, neither very successfully (though the Holley was much easier). I packed the stock qjet and sent it to Lars 3 years ago and couldn't be happier. Do I have a problem with the Holley? No. But the proper choke set up and air cleaner assembly, as well as the throttle cable were really enticing options to stick with the qjet.

Petes73

I do understand your point. I have used both also. I guess what bothers me is the holy war that's starts each time this comes up. If The OP wants help with his Quadrajet help him if he is asking about a Holley help him. This is a great hobby and there are multiple answers to every problem.