[Mike S]

I just got done building a very mild 400 for the street car, Headers and rpm intake,, 2801 cam, 8.8 comp and OD trans. It's just a cruiser.. Plan to taking it on road trips so milage is a concern. Right now I have a 750 holley vac secondary on it and runs really good. Just wondering If a smaller carb would be better, Thinking of a 600 holley or I have a 77 quadrajet laying around that needs rebuilding.
Do you think a 600 holley would be to small? Is a 77 quadrajet any good?

[steve25]

Nothing wrong with a 600 as they can support close to 400 Hp so it would not be. Restriction for your motor and it’s a bolt on with that intake.

If you want the best drivability under 4500 rpm I would try and sell the RPM and pick up a used Performer and then rebuild your Q-jet to use on it.

I ran a set up like that with my 79 TA for years and a with a Isky 270 mega cam it ran great and if I was to redo a car like that for everyday use I would do the exact same thing all over again.

You did not mention what body type this was in, but if it is in a TA I can tell you that opening up the rear of the hood scope is worth 5 Hp and nice added music to your ears at full throttle.

[i82much]

i dunno man. a 3310 ought to be just fine. i think you are gonna need a decade to save the cost of another carb in fuel expenses ... just dial in your 750 and enjoy.

[tom s]

use what you have.Tom

[b-man]

Originally Posted by tom s

use what you have.Tom

Agree 100%. Use the 1977 Quadrajet you already have.

The 1977 Quadrajet is one of the best ones, the casting quality is superior to earlier versions and it’s easier to tune as well as being an 800 cfm capable unit. I’d run that for a fuel economy road trip engine any day over a Holley.

With that said a 600 Holley is more than adequate, but I’d rebuild the Quadrajet with jetting advice from one of the forum Quadrajet gurus like Cliff R or Jeff (shaker455).

A Quadrajet is a fuel economy and performance carb all rolled into one, a Holley is just a performance carb in my opinion. Since you already have the carb you’re just a carb kit, an afternoon and a few jets and metering rods away from nirvana.

Just make sure the huge secondary throttle blades are not contacting the edges of the secondary openings on your RPM intake, a common issue.

[Tom Vaught]

Street Car, hard to beat a 1977 Q-Jet if dialed in properly.

Tom V.

[tom s]

I was speaking of the 3310 that on the car!Tom

[b-man]

Originally Posted by tom s

I was speaking of the 3310 that on the car!Tom

I knew that.

See what I did?

That’s what you get for posting just one short sentence.

[Schurkey]

Count me firmly in the Q-jet category.

HOWEVER, the common mistake I see folks making with Holleys--because they read the magazines, or see the time-limited dyno tuning video on youtube--is that they change the JETS to make the fuel curve right at WFO.

This works on the dyno. It's stupid for a street-driven car in real life .

The JETS are intended to be the part-throttle, high-vacuum "cruise" fuel metering. They should not be overly rich, maybe even a little lean. When the gas pedal is on the carpet, the POWER VALVE CHANNEL RESTRICTIONS should be adding the extra fuel, not the jets.

As a result of poor tuning of the Holley, the main jets are too big, and the PVCR aren't big enough. Cruise fuel economy suffers, tailpipe emission suffers...but it runs good for the 1% of the time the throttle is WFO, or when it's run on the dyno by folks who don't have time to drill the PVCR so they "cheat" on the jetting.

[i82much]

the avs2 edelbrock annular carbs get great reviews. i might try the 800 avs2 in place of my 850 double pumper one day just for the helluvit.

[77 TRASHCAN]

It won't take much to try that 600 Holley. BUT I'd want that 77 Quadrajet on my engine!!! I look at sw a pmeets for 77 and 78 Quadrajunks, every chance I get. I usually get them cheap, because of the front inlet tells the world its not for a Chevy!!!

Cliff has parts that most don't sell, and some of those parts come in his deluxe kit.

All Quadrajets need the primary throttle shaft bores bushed. Cliff sells kit for that. A 77 Quadrajet has a hot air choke. Cliff sells a kit to convert that to electric, and you will need that with a Performer intake.

Cliff has custom primary metering rods made that help with fine tuning. No one else has these?

Cliff can sell you ALL the parts you need for an initial installed flawless tune. If you buy his parts, you get any needed tech help needed, after the sale.

My thought on the Performer intake is to leave it on. The smaller runners provide possibly better port velocity than the RPM and likely the good stock iron units.

[b-man]

Mike already has the RPM intake installed that he wants to use, however I agree that the regular Performer would be a better choice for a moderate 400 build aiming for a balance between performance and fuel efficiency on road trips.

[Dragncar]

I good Q Jet is going to the best thing for this engine.
That said a 3310 is not a bad choice either.As efficient ? No, but they are easily tunable.

[Cliff R]

Since mileage is a concern the 1977 Pontiac Q-jet is about as good as it gets. They convert easily to e-choke, plenty of cfm (850), APT for full control of the part throttle A/F ratio, and dead solid reliable in long term service with the right parts in it I used a 17057274 on my last 5 engines and it was flawless for decades. Instant starts in any weather, fast idle for warm-up, and perfect fit as well. Over the years I tested everything out there against that carb and nothing would outrun it on the dyno or at the track and it used a lot less fuel for "normal" driving.

It will need a little help being emission calibrated. I sell custom rebuild kits with tuning parts to set them up exactly for the application so it will be plug & play right off the bench.......

[Mike S]

Thanks for all the info. I will probably try the quadrajet and see how it performs. Does anyone know if it has the attachment point for a 2004r TV cable?

The only reason I am using the RPM and Holley, is that's what I had on the 455 that was in the car. The old set up actually ran 11.70 at 3900lbs. But since I already have a race car wanted to build a nice cruiser.

[Half-Inch Stud]

Slap the 600 Holley on while you build the 77 Q-JET and mate to a 68-70 iron manifold.

I tink you will enjoy the difference in carb/intake combos, in the most convincing way.

Knockoff 90123 intake gaskets on ebay, maybe amazon, so maybe 9098s too.