4bbl carb for a 307?

[beermunk]

Recommendations on manufacture?

Recommendations on airflow?

Any advice/precautionary statements to making the change? Truck is a '69 lwb.
I know it won't be a racing motor but I'd still like to feed it a little more.

edited to fix spelling...

[stepside454]

assuming its an otherwise stock 307. Id recomend a Edelbrock Performer & a Q-jet. If your dead set on a Q-jet, my second carb of choice would be a 500 CFM Edelbrock....even though Im not much of a fan of Edelbrocks carbs. A Holley 570 would serv well also.

[Spanky_Pete]

I'm running a Edelbrock Performer intake with their #1406 600cfm carb on the 307 in my '72 3/4 ton. It also has a 350 cam, and moves the heavy truck with no problems whatsoever.

[beermunk]

Thanks all! I'm looking into the purchase right now...

(is it right to soup up the motor while ignoring the rest?!) heheeh

[beermunk]

Originally Posted by Spanky_Pete

I'm running a Edelbrock Performer intake with their #1406 600cfm carb on the 307 in my '72 3/4 ton. It also has a 350 cam, and moves the heavy truck with no problems whatsoever.

But i wouldn't need to change the cam to run that carb, right? Also, was that cam plugNplay or were there other changes you had to make?

[crazy longhorn]

Originally Posted by beermunk

But i wouldn't need to change the cam to run that carb, right? Also, was that cam plugNplay or were there other changes you had to make?

You should be fine with a 600 cfm Eddy on a stock 307, but I would for sure go with the elect choke version, as they are calibrated a tad leaner than the hand choke models. The 500 cfm is more suited.......but, if you upgrade later......well, the 500 is a tad small for a 350+ cube eng. best of luck, L

[Yankeelights]

Quadrajet, hands down. Properly tuned, you'll never be over carbed, they'll outperform just about any other carb and you'll get better mileage than any other 4bbl or 2bbl. They can be had rebuilt as low as $150 or you can do your own dirt cheap. There's lots of good information on rebuilding quadrajets on the web.

~ Dave

[jimfulco]

I also vote Q-jet, but on a stock iron non-EGR intake, and with a cold air intake system. And free up the exhaust so you can make better use of all that extra air flow.

If you're trying to do this on the cheap, find a stock air filter that has a hose connection so you can rig up a cold air intake. If the hose isn't real big, get another similar filter housing and rob the snorkel off of it and add it to the other one on the opposite side.

And you don't need to change the cam. The stock 307 has the same cam as a stock 350, and it'll work fine.

[71tahoe]

Originally Posted by jimfulco

I also vote Q-jet, but on a stock iron non-EGR intake, and with a cold air intake system. And free up the exhaust so you can make better use of all that extra air flow.

If you're trying to do this on the cheap, find a stock air filter that has a hose connection so you can rig up a cold air intake. If the hose isn't real big, get another similar filter housing and rob the snorkel off of it and add it to the other one on the opposite side.

And you don't need to change the cam. The stock 307 has the same cam as a stock 350, and it'll work fine.

I drove my Dad's 66 in high school. 283, 3 on the three, 3.73 or 4.11s. It had an iron intake and 4bbl Qjet. It would only do about 95 but man would it get there quick. Punch it at 70 and it made the most beautiful sound! If it's tuned properly a 307 should run even better.

[streetstar]

I had a 307 with a Holley 600 vacuum secondary carb -- mine was the hand choke model i got for $100 or 150 bucks at Super Shops. I had an aluminum EGR 4bl manifold from a mid '80's Corvette and had to use a carb adapter for the Holley flange.

I have fond memories of that setup because the 4bbl swap was my first automotive project .

The truck ran better and got the same mpg after the swap (11 mpg) as before

[beermunk]

Originally Posted by streetstar

I had a 307 with a Holley 600 vacuum secondary carb -- mine was the hand choke model i got for $100 or 150 bucks at Super Shops. I had an aluminum EGR 4bl manifold from a mid '80's Corvette and had to use a carb adapter for the Holley flange.

I have fond memories of that setup because the 4bbl swap was my first automotive project .

The truck ran better and got the same mpg after the swap (11 mpg) as before

I'm a bit confused here - now what is the difference between the hand choke and electric choke? I've seen choke knobs for sale on ebay, my truck has no such thing within the cab. I do, however, have to give it a couple of pumps on the pedal before cranking. I assumed that was because it's not fuel injected though.

[stepside454]

pumping the gas isnt
setting the choke, pumping the gas is just squirting some fuel into the plenum.
Hand choke is manual, you pull out a dash controled knob to set the choke for cold weather starts & warm ups, than you turn it back off bypushing the knob back in. With an elec. choke, 12V powers the choke, to set the choke you press the pedal to the floor once & let off after turning on the ignition. & than you kick the choke off, by later giving it a quick rev. I prefer elec. personally

[Billla]

A little hesitant to jump in here

A 307 will never use more than 500 CFM unless you're turning it past 6K. Most (not all) Q-Jets flow 700+ CFM. They have very small primaries and HUGE secondaries, so they work on almost any engine - just like any other vacuum secondary carb - and the very small primaries will work well on a smaller engine. I agree that the Q-Jet secondary opening (air valve) can be adjusted to accomodate the 307, and that you might bet able to get one that's in the ballpark on jetting - but I disagree that they're easy to tune. The jets and rods aren't all that easy to get, and making accelerator pump changes requires some real effort. I love the Q-Jet for a near-stock configuration - but IMHO it's not the best performance carb.

If you think you're going to a larger engine at some point, a 600 CFM Edelbrock is your best choice IMHO as suggested by other folks. It can be easily tuned to be right on for your 307, and has capacity left over for a 350 or even a mild 383. Spend some money on a dyno tune (~$200) and you'll be very happy with it. As noted, it's not going to be right out of the box, so you need to factor the tuning cost (if you can't do it yourself) into the overall cost. The Performer is a good manifold choice.

[Yankeelights]

Some 305s had Quadrajets and Quadrajets don't run 700 cfm at idle. I've had 283s with quadrajets and I know of at least one 250 6 cyl that runs awesome with one. I also ran a 12 second 406 topped off with a quadrajet. They aren't all that hard to tune. They just aren't as easy as a Holley. Like anything else, it's all a matter of how much effort you want to put into it. If you do decide to put the effort out on a Quadrajet, you'll be happy that you did and if you decide to go to a bigger engine, you're ready unless you go to a high reving big inch big block.

Here's some links for Quadrajet parts. This is where I shop and the folks are eager to help:

www.carburetion.com

www.jetchip.com

PS: Probably the toughest thing to do on a Quadrajet is installing bushings on the throttle plate if needed. I do my own, but most automotive machine shops are willing to do it for you, usually under $25.00

~ Dave

[Billla]

Originally Posted by Yankeelights

Quadrajets don't run 700 cfm at idle.

They aren't all that hard to tune. They just aren't as easy as a Holley.

Well...I don't know any carb that runs at 700 CFM at idle As noted, the Q-jet's big advantage is huge vacuum secondaries.

Compare the price of a tuning kit for a Q-jet at $130 vs. the price of the Edelbrock kit at $36 I don't disagree that it's a matter of effort, but in my experience it requires more effort to tune a Q-Jet than an Edelbrock or Holley as you note.

Edelbrock makes very nice and complete Q-jet tuning kits with jets, rods, springs...everything.

[Yankeelights]

I don't buy the tuning kits because they tend to soak you and provide parts that aren't needed. For my latest Quadrajet rebuild a couple of weeks ago, I bought a core carb from a ram air pontiac on eBay for $30 that included shipping; $26 for a good rebuild kit; $30 for primary jets & rods; $12.00 for bushings and $8 for a choke pulloff. I spent much more than what would be needed for a 307. The pontiac Quadrajet has a nice little feature (transistion slots on the secondaries) that makes a smooth transistion from primary to WOT and similar slots can be cut into any quadrajet. If I were looking for a Quadrajet for a 307 I'd use one for a 305; more than half the battle is won but for a $26 rebuild kit and bushings, if needed. If the 307 has a hot cam, then I'd find one from a 350 for a good starting point.