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Off-Road Carb Tuning

EarlyElway

Jr. Member
Joined
Dec 11, 2012
Messages
58
Loc.
Shawnee, KS
Hello,

One of the first times I had my rig out on the trails and I got on a steep incline my Bronco died. I was told that this was most likely due to the carburator. I know that several of the sites out there sell "off road" carbs but I was curious if there is a way to tune mine to accomodate and not have to replace it or any other recommendations.
 

bmc69

Contributor
Bronco Guru
Joined
Jun 11, 2004
Messages
11,879
My standard approach is to unbolt, throw away..install EFI. ;-) But if that's not currently an option for you, there are some things you can do with some carbs.

To start off...what carb do you have?
 

half cab

Contributor
Guru Bronco
Joined
Dec 8, 2010
Messages
16,281
Some of the 2150 motorcraft carbs had a fuel bowl spacer that trapped fuel for off level situations.
 

Justafordguy

Bronco Guru
Joined
Sep 26, 2009
Messages
6,253
If you want to keep it carb'd you need a Motorcraft 2100/2150. Best off road carb out there. If you need a 4bbl for some reason the Quadrajet can be made to work good off road as well.
 
OP
OP
E

EarlyElway

Jr. Member
Joined
Dec 11, 2012
Messages
58
Loc.
Shawnee, KS
It's 4 bbl Edelbrock carb. Not sure of the model. I know they make an off road version however I don't believe that it is one as I remeber checking and the numbers inscribed on it don't match the off road verstion on wildhorses website.
 

okie4570

Contributor
Bronco Guru
Joined
Jul 16, 2012
Messages
9,298
Loc.
NW OK
It's 4 bbl Edelbrock carb. Not sure of the model. I know they make an off road version however I don't believe that it is one as I remeber checking and the numbers inscribed on it don't match the off road verstion on wildhorses website.

I got rid of my 4bbl Edelbrock last year and went with a quadrajet and haven't looked back. No regrets and no more stalling out when the bronco is pointed upwards.
 

bmc69

Contributor
Bronco Guru
Joined
Jun 11, 2004
Messages
11,879
It's 4 bbl Edelbrock carb. Not sure of the model. I know they make an off road version however I don't believe that it is one as I remeber checking and the numbers inscribed on it don't match the off road verstion on wildhorses website.

Ick.Worst of the worst as far as off-road performance goes....and I've tried every trick there is because I otherwise like those carbs a lot.

Block off the transfer passage between the two bowls. Install the "off road" needle and seat kit. Install a fuel pressure regulator so you can turn down the delivery pressure to 1.5-2 psi while wheeling.
 

spap

Contributor
Bronco Guru
Joined
Jan 2, 2010
Messages
2,525
I had the four edlebrock carb years ago I didnt like incline s at all
You can always try stiffer sprigs for the float that s helps a bit can t really do a tune from what your describing
 

70_Steve

Old Guy
Joined
Dec 13, 2002
Messages
8,317
It's 4 bbl Edelbrock carb.
I ran a Carter AFB, which is the same thing as an Edelbrock Performer, for several years, until it left me in a bad place a few times. Which is why I now run EFI.

There are a couple things you can do to improve the Edelbrock Performer. Note, I said "improve"... It will never run well off-road, no matter what you do.

Here is a collections of posts I copied years ago off of Pirate.
 

Attachments

  • Edelbrock Off-road.pdf
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SteveL

Huge chevy guy
Joined
Jun 24, 2001
Messages
11,715
Loc.
Hawthorne ca
As good as those edelbrock are on the street they suck off road. I also tried the mods with no luck. Now both broncos run q-jets. One note on the q-jet carry spares of the little in carb filters. It will go from running awesome to total crap when it clogs. They don't clog often but I guess that depends where u drive and condition of your tank
 

66BlueGoose

Contributor
Sr. Member
Joined
Feb 6, 2014
Messages
408
When I hit the trail, first thing I do I bump the idle a few hundred rpms , that helps a bit. Running the 2100.
 

AZ73

Contributor
Bronco Guru
Joined
Mar 28, 2012
Messages
3,546
You can try tuning, but it's not going to help much. You'll still get stuck in higher angle situations with that carb. Qjet is the way to go if you can't swing EFI yet. You might want to read this thread. Carburetors Unlimited in Phoenix has done a ton of these for Broncos.

http://classicbroncos.com/forums/showthread.php?t=259544
 

bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,917
I Love my 670 Holley T/A.

Never bogs. It has been great. Holley tech line is second to none.
 

Eoth

Bronco Guru
Joined
Mar 10, 2004
Messages
1,680
X2 for Truck Avenger for off road but I could never get it quite right for street... I now have one carb for offroad and one for street. Just takes a couple of mins to swap them.
 

YNOTBOB2007

Full Member
Joined
Oct 2, 2007
Messages
207
I have the 2150 and mine used to stall on steep inclines too. After I reinstalled the fuel pressure regulator (that the shop removed!) the stalling disappeared. The shop (that I no longer go to) said the FPR was not needed as it was not stock. I don't think they ever took their vehicles out on the hills.
 

jckkys

Bronco Guru
Joined
Mar 15, 2012
Messages
5,202
Since you have an AFB (the actual name of the model), that was designed by Carter and made by Webber, you must also must have a 4bbl square bore intake. The obvious choice is a 1.08" 4100. The primary side is identical to the 2100 the truck came with and secondaries that add mare than enough flow for a 302 or 351. I have both a 500CFM AFB and a 480 CFM 4100. Both are low maintenance leak free and trouble free. The 4100 has become a high dollar piece so I run the $25 Carter AFB for daily driving and the 4100 when on fishing, hunting, or scouting trips. Holley Truck Avengers suffer from all the typical Holley gasket leaks and get poor mileage, plus they're way over priced. Square bore intakes and the Ford throttle linkage aren't compatible with GM Q-Jets. Finding tuning parts to dial in a Q-Jet is far from easy in contrast to AFBs and Holleys. The 4100s were made for Ford engines so tuning is rarely needed. The 4100 like the 2100 is excellent off road. I found mine for $80 on ebey so cost wasn't bad, tho finding a good one at a good price can take patience. Kurt Praxl at kpcarbs.com will refinish and repair a 4100 to look and work like new. Now that Ford-Holley throttle shaft repair kits are cheap and easy I think I'll run the 4100 full time. Q-Jets need throttle shaft repair more than any other carb, now that I'm on that subject.
 

twisted 66

Contributor
Sr. Member
Joined
Oct 30, 2008
Messages
454
Loc.
Norcal-Tracy
I think asking which carb is best is the same as asking what is better Ford, Chevy, or Dodge. You are going to get a lot of different answers and possible leave your head spinning a little. The key to any carb is tuning. However you must have also have good ignition timing/advance curve etc.. to go along with good carb tuning. Some folks do not understand how to find tune one or the other or both and then develop a negative thought on a certain brand. Bottom line what ever one you get do your homework on it so you understand all of the tuning that can be done. No question EFI is the way to go but cost more $$.Just my.02
 

ntsqd

heratic car camper
Joined
Jan 30, 2005
Messages
3,390
Loc.
Upper SoKA
Q-Jets need throttle shaft bore repair because GM put their return springs on the portion of the arm below the shaft. So now both the spring AND the throttle linkage are pulling the shaft against the bore. Don't do this. Put the return spring inline with the linkage.

As to adapting a spread bore carb to a square bore intake, there are good adapters and there are inexpensive adapters. Pick one, you don't get both.

Wish that I had the magic info to make an AFB pattern carb work great off-road. I know that it has been done and the one on the Bronc-up does work surprisingly well considering all of the problems others have had with them. I don't know what the PO did to it to make it work, but I was expecting trouble on it's first outing to Calico and I had none.

"AFB" isn't the name of the carb model, its the acronym. "AFB" stands for "Aluminum Four Barrel" according to my book on tuning them.
 
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