off-road carb - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep CJ Forum > off-road carb

Introducing MONSTALINER™ UV Permanent DIY Roll On Bed LineSavvy Billet LED Tail LightsLight up the holidays with LED lights from JeepHut

Reply
Unread 02-11-2009, 06:30 AM   #1
Axlesnap
Registered User
1975 CJ5 
 
Join Date: Feb 2009
Location: Utah
Posts: 40
off-road carb

ok fuel injection is not an option now, so trying to keep what I got that is a stock 304 and stock two barral carb, what can I do to make this thing Moab ready? I usally run extreame trails. Is this possible with this carb?

Axlesnap is offline   Reply With Quote Quick reply to this message
Unread 02-11-2009, 11:32 AM   #2
wendell
Registered User
1987 YJ Wrangler 
 
Join Date: Aug 2006
Location: grafton ohio
Posts: 3,292
holley make the truck avenger series 4 barrels for off road, they can take some extreme angles. I run a 470 TA 4 barrel on my 258 with an offy intake, cam and header, it works awesome off road. I don't miss FI at all, it performs great and there's no computer or sensors to worry about.
__________________
1987 wrangler, 258 I-6, 5-speed.
2007 liberty sport 4X4, automatic
2009 ford ranger 4x4 FX4 OFF/ROAD, 5-speed
wendell is offline   Reply With Quote Quick reply to this message
Unread 02-11-2009, 11:56 AM   #3
John Strenk
Moderator
 
John Strenk's Avatar
1976 CJ5 
 
Join Date: Feb 2005
Location: Shalersville Ohio
Posts: 13,234
Do you have the Carter 2bbl or the MC2100 on that V8 right now?
John Strenk is offline   Reply With Quote Quick reply to this message
Unread 02-11-2009, 11:07 PM   #4
Axlesnap
Registered User
1975 CJ5 
 
Join Date: Feb 2009
Location: Utah
Posts: 40
MC 2100, I know of alot of rock crawlers are running older quadra-jets backwards. Has any body done this? Would it work?
Axlesnap is offline   Reply With Quote Quick reply to this message
Unread 02-11-2009, 11:09 PM   #5
sweetguardian00
Registered User
1946 CJ2A 
 
Join Date: Jan 2008
Location: Massachusetts
Posts: 573
my little EMPI 38/38 some some insane angles and never choked out on me
__________________
1946 CJ-2A 225/T90/D18
1966 CJ-5 231/T86/D18
1986 CJ-7 258/TF999/D300
1984 C-10 6.2/SM465
Yeah it's a Diesel
sweetguardian00 is offline   Reply With Quote Quick reply to this message
Unread 02-11-2009, 11:19 PM   #6
Axlesnap
Registered User
1975 CJ5 
 
Join Date: Feb 2009
Location: Utah
Posts: 40
on this carb
Axlesnap is offline   Reply With Quote Quick reply to this message
Unread 02-12-2009, 05:49 PM   #7
Axlesnap
Registered User
1975 CJ5 
 
Join Date: Feb 2009
Location: Utah
Posts: 40
anybody with tech on this, the truck avenger is crap used it
Axlesnap is offline   Reply With Quote Quick reply to this message
Unread 02-12-2009, 08:55 PM   #8
dhubing
Registered User
2005 TJ Wrangler 
 
Join Date: Jun 2008
Location: Naples, FL
Posts: 179
I currently run a Holley that is junk offroad. I have been told that the MC2100 is excellent offroad.....
Now this makes me wonder... No rocks for me - only trails and mud (but there is the occasional hill)
dhubing is offline   Reply With Quote Quick reply to this message
Unread 02-12-2009, 11:37 PM   #9
JeepHammer
Running On Empty...
1973 CJ5 
 
Join Date: Aug 2007
Location: South West Indiana
Posts: 10,707
It isn't the Holley that is junk... It's the guy tuning it.

---------------------------------

Holley has a LOT of advantages off road, You just have to be bright enough to seek the correct parts...

And all the 'Correct Parts' will fit in about 95% of the two barrel carbs, since the Holley 2 barrel is just half of the 4 barrel carbs!

Start with something that is sized properly for your engine,
The math will probably scare about 90% of the people off, but here goes...

304 CID is a '4 Stroke' engine, which means only HALF the cylinders fire on any given revolution of the engine.

304 CID ÷ 2 = 152 CID per Engine Revolution.
152 CID X 85% Volumetric Efficiency (152 X .85 = 129.2 CID per Rev.)
129.2 CID X 5,000 RPM Rev Limit = 646,000 CID per MINUTE.
646,000 CID ÷ 1,728 (Cubic Foot) = 373.842 Cubic Feet Per Minute at Top RPM...

So a 390 CFM two barrel will be more than your little 304 will EVER need!
----------------------

Now, on to the 'Off Road' tuning...

Sideways tilt is called 'Off Camber',
Nose Up or Nose Down is called 'Pitch'.
You will need to know these to understand the tuning for 'Off Road use'.

Lower the fuel pressure a little.

Holley does fine between 4 and 7 PSI, and for Off Road, I normally try for about 5 PSI fuel pressure.
Keeps the fuel from blasting in right away anytime the float bobbles on ruts.
Cost, usually nothing since factory mechanical fuel pumps are set to about 6 PSI.

Lower the float level a tad.

About 1/16" makes a LARGE difference in off camber situations.
Keeps the float from opening the inlet valve (needle & seat valve) when you lean the vehicle 'Off Camber' as easily.
Cost, NOTHING, adjustments built into the carb.


Spring Loaded Needle & Seat!
These are even called 'Off Road' needle & seat valves, but buttheads simply will not spring for the few bucks and 5 minutes it takes to install them,
they would rather b!tch about the 'Holley'...
They would rather fix blame than fix problems!
Cost, about $22, Holley p/n 6-513
http://store.summitracing.com/partde...5&autoview=sku

-----------------------------------------

Spring loaded inlet valve keeps the valve/float from 'Bouncing' the valve open and flooding the carb.

Power valve AT LEAST 2 InHg below 'Part Throttle Cruise' vacuum reading.
I'm running mine at 2.5 InHg below PTC and I'm thinking of going lower.
This keeps low vacuum when you are pulling or trying to 'Finesse' an obstacle from opening the power valve and flooding the carb at 'Crawl' or 'Idle' speeds.
You need the PTC vacuum reading to get the correct power valve, so I can't give you a part number...
Correct Power Valve, $10


---------------------------------------

Serious off roaders running Holley even take the power valve completely out and use a plug, jetting up a little to compensate for loss of power valve enrichment...
I don't recommend this if you are going to drive this vehicle on the street at all!
Power Valve Plug, Holley p/n 26-36 , $4.50
http://store.summitracing.com/partde...5&autoview=sku


-----------------------------------

Anti Slosh Tube in the top of the float bowl to vent.
Cheap and effective.
http://store.summitracing.com/partde...5&autoview=sku


------------------------------------

Raising float bowl vent(s) up inside the air cleaner so fuel can't just spill into the Venturis. This can be anything from 3" of rubber fuel line, to 3" of metal fuel line...
VERY easy and cheap to do.
-------------------------------------

Main Jet extensions... Cost about $8.
Move the jets away from the valve body to the center of the float bowl where they are less likely to suck air instead of fuel.
Keeps you from 'Sucking Air' on extreme Pitch (nose Up/Down) grades.
http://store.summitracing.com/partde...5&autoview=sku


---------------------------------------

Everyone wants the big old Center Pivot float bowls because they look 'Cool'...
But, they have a big, wide, flat float inside.
When you lean the vehicle (off Camber), you uncover one end of the float, and it looses lift and allows the inlet valve (needle & seat) to open, flooding the carb.



Side pivot float bowls aren't as cool looking,
But the use a smaller, rounded float that doesn't have the lift problems off camber!



----------------------------------

[b]And just to clear some things up,

MC-2100 is a HOLLEY carb, Designed by Holley, Built By Holley for Ford/Motorcraft.
Later Versions were casted/machined other places, but the first few years of the MC-2100 carbs were made by Holley, and it's still a Holley design.

Explains why they have 'Power Valves' and the like!
JeepHammer is offline   Reply With Quote Quick reply to this message
Unread 02-13-2009, 12:07 PM   #10
dhubing
Registered User
2005 TJ Wrangler 
 
Join Date: Jun 2008
Location: Naples, FL
Posts: 179
I am going to try this before I get rid of the Holley - Thanks!
dhubing is offline   Reply With Quote Quick reply to this message
Unread 02-14-2009, 11:19 PM   #11
sweetguardian00
Registered User
1946 CJ2A 
 
Join Date: Jan 2008
Location: Massachusetts
Posts: 573
Jeephammer, i don't know you personally, only on the Forum, and i will say that not only do you think for 2 seconds before you post, but you also know how to tell people things so they listen to you. as for the Holley tricks, this might get the Willys Pickup running properly again!
__________________
1946 CJ-2A 225/T90/D18
1966 CJ-5 231/T86/D18
1986 CJ-7 258/TF999/D300
1984 C-10 6.2/SM465
Yeah it's a Diesel
sweetguardian00 is offline   Reply With Quote Quick reply to this message
Unread 02-15-2009, 10:33 AM   #12
wendell
Registered User
1987 YJ Wrangler 
 
Join Date: Aug 2006
Location: grafton ohio
Posts: 3,292
There was a tech article in the last edition of jp magazine thats tells you you how to turn any holley carb in to an off road banger.
__________________
1987 wrangler, 258 I-6, 5-speed.
2007 liberty sport 4X4, automatic
2009 ford ranger 4x4 FX4 OFF/ROAD, 5-speed
wendell is offline   Reply With Quote Quick reply to this message
Unread 02-15-2009, 11:28 AM   #13
Cherokeester
Registered User
1980 CJ7 
 
Join Date: Jun 2004
Location: Utah!
Posts: 710
Truck Avengers have almost everything that Jeephammer is talking about installed and tuned at the factory. I have a 470 on my 304. From personal experience I must tell you that carb has never loaded on me once on any trail in moab. I have my Jeep so steep I had to lean forward to keep it from rolling over backwards and the engine never missed a rotation as it were. I recommend a properly tuned Holley highly. Follow Jeephammers directions above and you will be pretty happy with the performance.
__________________
1980 CJ-7 with a AMC 401, RE 4.5" Lift, 4-1 Dana 300, Holley TBI Projection, 35" Goodyear MTR's
2010 Rubicon Unlimited
1997 TJ with various enhancements
Cherokeester is offline   Reply With Quote Quick reply to this message
Unread 02-15-2009, 02:13 PM   #14
JeepHammer
Running On Empty...
1973 CJ5 
 
Join Date: Aug 2007
Location: South West Indiana
Posts: 10,707
Quote:
Originally Posted by wendell View Post
There was a tech article in the last edition of jp magazine thats tells you you how to turn any holley carb in to an off road banger.
A lot of the stuff we come up with here makes it to the 'JP' magazine, usually with LOTS of errors!
Don't think for a second that JP, 4 wheeler, ect. aren't trolling the bulletin boards, but taking ideas!

I've seen my work reproduced word for word, right down to mistakes I made in part numbers reproduced, so we KNOW where it's being lifted from!...

Just remember, YOU HEARD IT HERE FIRST!
I've been doing Holley 'Off Road' diagnosis for 10 years on these forums, and the information hasn't changed since I worked for Holley 25 years ago...

I do wish they would acknowledge where they got the information for their 'Original' article from once in a while!
Instead of just pumping the articles full of stuff from vendors that advertise in their rags!
JeepHammer is offline   Reply With Quote Quick reply to this message
Unread 02-15-2009, 02:18 PM   #15
JeepHammer
Running On Empty...
1973 CJ5 
 
Join Date: Aug 2007
Location: South West Indiana
Posts: 10,707
Quote:
Originally Posted by sweetguardian00 View Post
Jeephammer, i don't know you personally, only on the Forum, and i will say that not only do you think for 2 seconds before you post, but you also know how to tell people things so they listen to you. as for the Holley tricks, this might get the Willys Pickup running properly again!
You know, when the guys that like to name call, cause problems, ect show up, the say I'm too long winded...
That people don't WANT to know what is causing the problem, just what part number will FIX the problem...

Thinking like that is what gets engines declared 'Blown Up' and scrapped over leaking exhaust or bent rocker arms...

I believe that EVERY ONE OF YOU SERIOUS GUYS wants to know what is 'Causing' the issues,
What steps can be taken to correct the 'Issue',
and what is available to HELP correct the 'Issue'...

If you know what causes it, then you can figure out how to fix it the next time!

I may be azz-backwards in that thinking, but there sure are a lot of guys that soak this stuff up and have vehicles running because someone shined a light on a specific 'Issue' and they fixed it! And now have a RUNNING vehicle instead of an expensive lawn ornament!
------------------------------------------------------

Quote:
Originally Posted by Cherokeester View Post
Truck Avengers have almost everything that Jeephammer is talking about installed and tuned at the factory. I have a 470 on my 304. From personal experience I must tell you that carb has never loaded on me once on any trail in moab. I have my Jeep so steep I had to lean forward to keep it from rolling over backwards and the engine never missed a rotation as it were. I recommend a properly tuned Holley highly. Follow Jeephammers directions above and you will be pretty happy with the performance.
'Truck Avengers' are the culmination of about 30 years of Off Road experience from some really inventive guys!

When Holley dipped into trucks, they found out two things really quickly...
1. We don't go in stright lines 1/4 mile at a time,
2. We don't go in tight left hand circles!

SO!
They had to address things like fuel sloshing out of the float bowl into the vent tubes...

Taller vent tubes kept the fuel from getting out as easily,
(look at the top vent tube front to rear over the ventruis, it's drilled full of holes at the top, and that raises the flow bowl vent by 2" or better!)

'Whistles', plastic vent extension that go inside the float bowl to keep the fuel from leaking out of the front bowl when going UP a steep hill,
Or in the rear to keep fuel from leaking going DOWN a steep hill,
(or during hard acceleration or braking, stolen from dragsters)

Jet extensions to keep the fuel from uncovering the Jets when going up or down steep hills.

Round floats to keep the flat bottom float from doing weird things when you lean the carb way over (actually stolen from FARM TRUCK carbs!, Farm Trucks get leaned over all sorts of strange ways!)

Spring loaded needle and seat,
Keeps the weight of the float on the end of that float arm from 'Bouncing', works sort of like a 'Shock Absorber' to keep the needle and seat under control when you are bouncing around or 'Washboarding' through some obsticle!
(and YES! We ALL go too fast though those sorts of things, you aren't the only one! )

This is all common sense...
The biggest problem we have with Holleys is power valves, and 15 minutes with a vacuum gauge will eliminate 90% of those problems!

Power valve 1 InHg to 1.5 InHg below your 'Part Throttle Cruise' vacuum reading if you are 'Hot Rodding'...
Lets the enrichment come 'IN' right away when you 'Goose' the throttle.

2 InHg to 2.5 InHg below your 'Part Throttle Cruise' vacuum reading when you are off roading the vehicle some,
This keeps the Power Valve closed when you are at idle, and just trying to 'Goose' the throttle to 'Finesse' an obstacle... So the vehicle doesn't 'Load Up' or 'Flood Out'...
(rock crawlers and rock racers don't 'Finesse' anything!)

You still want that power valve working if you drive on the street!
That is a REAL FUEL SAVER when you are on the street, and doesn't do a bad job on trail rides keeping the fuel consumption at reasonable levels!

Plug the Power Valve and jet up the carb to compensate if you are ONLY off roading at serious angles all the time...
Rock Racers don't care about 'Finesse' or 'Fuel Mileage', so they can do without it.
........................................

Lower your fuel pressure a little, just a pound or two.
This keeps large volumes of fuel from squirting into the float bowl every time the float gets jostled around,
OR anytime the fuel is 'Off Camber' in the bowl and uncovers part of the float...

Also, your needle and seat are balanced between the lift the float is getting from the fuel in the bowl,
And the fuel pressure in the line trying to blow the needle off the seat!

When you lower the fuel pressure a tad, this gives you float more leverage to control the fuel flow! Simple, easy, reliable 'REVERSIBLE' if you need more fuel pressure later, and will make a HUGE difference in a lot of situations...
....................................

LOWER THE FLOAT LEVEL...
This costs NOTHING, and allows your carb to go more OFF CAMBER before the needle and seat open, flooding fuel in like crazy!
Just about one or two flats of the adjusting nut is all that is needed to make some HUGE differences in performance...

Two reasons,
1. The leverage of the float/arm on the needle and seat breaks over at about 'Optimum' float level, which is fuel just creeping out of the bowl float level plug threads...
So if you lower even 1/16", the float/arm can often get better control of the float level.

Secondly, lowering the float level will often keep fuel from doing 'Strange' stuff...
Leaking out the bowl vents, creating too much pressure on the main jets, lowers the fuel level in the emulsion tubes, ect.

We aren't talking 'Coon Tuned' race cars here battling over 1/100 Second in 1/4 Mile,
We are talking the difference between getting the darn thing to run on a 10° off camber situation!
................................

The most EXPENSIVE thing you will run into...
And I suggest you look for a USED carb or set of float bowls, since most all float bowls will interchange.

Center Hung Float Bowls use wide, flat bottom floats, that do TERRIBLE off camber!

Side Pivot Float Bowls use round bottom floats, witch handle off camber tilt angles MUCH better!
(See Pictures in my post above for floats)

Anyway, it's all in the tuning and some cheap parts, not really hard for anyone to understand once it's explained in practical terms.

Last edited by JeepHammer; 02-15-2009 at 08:25 PM..
JeepHammer is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.