Carb Options/Suggestions

[joebronco73]

Hey, all. I have done some searching regarding carburetor size, brands, and other options, but can't seem to find the most clear recommendation. Right now, I have an Edelbrock 1405 (or 1406), which is a 4bbl, between 600 and 650cfm. Its been rebuilt and tuned, but I have never been truly happy with it. I think the carb is just too big for it. The engine is a mildly built 302, balanced, cam, but all original heads and block, which is bolted to a brand new C4 and stock rear end. This is going to be a regular driver and will see some (not a lot) wheeling.

My question is: what model/size/brand of carb would you all recommend? I have seen a lot of Bronco's with similar engines running the Motorcraft or Holley 2bbl carbs that are between 350 and 500cfm. Thanks for the input, in advance ;D

 

[jckkys]

A 400 CFM 4bbl is plenty for a 302. The Holley 390 CFM is an almost perfect size. They also make a 450 CFM List 4548 that has a 100 percent Ford throttle lever with the kick down. I run a 500 CFM AFB by Carter that Edelbrock now markets as a 1403. It's an excellent daily driver carb on my 351. The best available would be an Autolite 4100 480 CFM 4bbl with 1.08" venturis. It's just a 1.08" venturi 2100 2bbl that's stock in EBs with 2 more barrels that open at high RPM full throttle. They're both better than the AFB or Holley off road or a trip with a range of altitudes.

 

[joebronco73]

Thanks, jckkys. Is there proportion with the venturi size to the cfm rating or number of barrels that I'm not aware of? I noticed some of the 350cfm, 2bbl carbs had 1.20" venturis.

 

[needabronco]

You can step up in meter rods on that Edelbrock to further tune it to work. Download the tuning book from Edelbrock and read it several times until it starts to make sense. I ran an 1806-'Off Road' Edelbrock which is a 650cfm carb on my 302 and once I tuned it worked very well, I even got 16-18 MPG's out of it regularly. In my experience the Edelbrock's are a little harder to understand to tune, but once you get it, it will stay tuned.

 

[NYLES]

Barry Grant 575 speed demon

 

[Lawndart]

I ran a Holley 600 for about a year and I was never satisfied.
I now run a Holley 390 with a 31 squirter and love it.

 

[bronconut73]

I know y'all are going to flame me but I love my Truck Avenger (670). But they make a smaller one too.

 

[69_Sport]

A properly tuned, smaller cfm carb, in general, will provide better throttle response and all around drivability under most conditions at the expense of full throttle horsepower. Most of us are not running our carbs at wide open throttle very often anyway, so it makes sense to run the smaller carb. Ford built many, many small blocks during the early Bronco's time with 350-500 cfm 2 and 4 bbl carbs for this reason.

 

[joebronco73]

That's why I think a smaller 4bbl may be a better choice for me, but I can try retuning the carb. My concern is that a professional carb tuner has already done that, so I can easily screw that up ;D

 

[RODRIG3911]

I have a Holly Truck avenger Carb and LOVE it. I had originally bought the 470CFM and had no power. I called Holly up and they told me I needed the 670CFM and exchanged it for me. My Bronco runs great now on and off road

 

[rguest3]

Holley 450cfm mentioned earlier

Holley Truck Avenger 470cfm

Autolite 4100 - 1.08 Venturi, 480cfm - My personal favorite carb.

Any Carb will need to be tuned for your application.

 

[jckkys]

The reason 2bbls seem to flow more with the same size venturi that's 1/2 the same size venturi 4bbl is the they are rated differently. The 1 and 2 bbls are flowed with a larger pressure differential than 4 bbls. So a 1.08" venturi 2100 is rated at 287 CFM but only flows 240 CFM when rated with the same methodology as the 4 bbl 1.08" venturi 4100 rated at 480 CFM.
The positive advantages of smaller carbs aren't possible with Truck Avenger Holleys. The unique piece they have in the metering body starves the engine for fuel with high venturi air speeds that yield the best MPGs, and drive abillity. Holley techs will tell you the Truck Avengers sacrificed these for the abillity to keep the engine running at extreme angles.
The Ford 2100,2150, and 4100s don't sacrifice these benefits while handling grades and side slopes better than other Holleys besides the Truck Avenger. If you go off road but don't do rock crawling, the 2100/4100s are the best carbs.

 

[DuneBuster]

Don't change you have a great carb, but you need to set it up

I have the same Edelbrock. it was on it when we bought the Bronco. It ran crappy and very rich. I highly suggest you buy their carb rebuild kit and calibration kits (Jegs, summit). You get everything you need, gaskets, springs rods, jets and springs. and more importantly the manual. After rebuilding and RTFM (Reading The Manual) which was not that hard to read, we realized it was set up way to rich in both normal and power modes. The manual showed how to do the setup and it was easy to set up adjust and make it run great. We go to Sliver lake dunes and hill climbs and it runs fine uphill, downhill or sideways.

We did not have a kickdown linkage originally and bought the Lokar Kickdown cable and integrated that into the spring from the gas pedal to the carb and now it kicks down like a champ at the right time.

oh, and it starts great too!

 

[joebronco73]

All great info. Dunebuster, that's exactly what I'm thinking I need. It's been rebuilt, but I don't know that it has been properly tuned ON THE ENGINE. It also received a new kick down unit as well, so that may have changed the tune on it.