Best Carburetor

ok know I can't spell. As stated earlier I just got my engine for my jeep!! it's a 304 that came out of a Javelin. I will probalby need to get a carb for it and I am wondering what you suggest.

For some info. I live in Central Utah at 5600ft and will have it up above 9000ft regularly.

 

Re: Best Carburatur

4bbl? Junkyard Q-Jet. Quite honestly, I've tried EVERY manufacturer's off road carb and a $15 junkyard Q-jet with a $15 NAPA rebuild kit works just as well (or better in some cases) as a fancy $400 aftermarket jobbie. Look for a Camaro, Firebird, Monte Carlo, etc with a 305 and nab one off of it. It'll have a lot of emissions stuff you won't need, but it'll be jetted to work with a small displacement engine like your 304. You don't want one off a big block or 350 since you're at elevation. The extra fuel delivery won't be welcome.

If you want new, Edelbrock stopped making their Q-Jet (I was bummed) but Summit Racing sells rebuilt ones for a decent price. And there's always JET Performance. They made their name building and tuning these carbs.

If you want a square bore, then a Truck Avenger from Holley is what I usually run. I'd go for the 470cfm Truck Avenger for your little 304.

 

Re: Best Carburatur

If you are thinking 2bbl and altitude is an issue you may want to look for a 2100/2150 Motorcraft off the later Wagoneers & Cherokees that has the " Aneroid Barometer Altitude Compensator " built into it. They may have offered these on the later Cj's with the 304, Salvage Yard Networking may turn one up.

 

This has been discussed several times before and I guess the consensus is the motor craft 2100 can't be beat. I personally like my Holley. It is a 2bbl replacement for the 2100 and is a direct replacement. Do you have an intake or will you need to get one. The stock 2bbl manifold is very heavy.
I live in northern NM at 6200 ft.

 

As far as a four barrel carb goes...I have to agree with what was said about the quadratoliet. They absolutely work better than the Holley truck avenger. It's the closest a carb will come to fuel injection when off-road.
I am a Holley fan myself...and I have many years of experience tuning them...If the proper mods are done...they work great...but still not quite up to snuff with an old quadrajet when in the rough stuff.

 

Good point Larry, I agree ( and should have mentioned )that the 2bbl Holley is a good carb and there would be no reason not to run one. I have run some Holley's in the past and had no trouble with them.
I only mentioned the 2100 because allot of them were used on the Jeep line in the AMC days and it may be easier to find one that is calibrated for the 304. But I should not have left the Holley option out, My bad

 

I second the 2100. I had a Holley on my 304, and it sucked off road. I found a 2100 on Ebay for $150, rebuilt and calibrated. If anyone wants a 2 bbl Holley I have one double cheap.

FWIW I live at 6500' and it goes up from there.

 

Yep, me too. Terrible. At some attitudes it just wouldn't run without pumping the pedal. A significant power increase, but almost undrivable off-pavement. I'd avoid the 2300 or 4160 Holley carbs for a Jeep.

 

Holley's have gotten a really bad rap for an off-road carb (excluding the truck avenger)...Some of it they deserve...Because the fact is...if you buy a Holley, do nothing to it and stick it on your Jeep...it will slosh and slobber and flood when you start bouncing around. The thing is though...a Holley is much like anything else...it's as good as the amount of work you put in it.
Many folks would rather skip right past all the "shave this off, add this, fill this full of marbles springs and etc" and just bolt on a carb that will work good off-road right out of the box...and really, who can blame them.
However...a blanket statement about Holley's being poor off-road should not be done...
One big example to this (and this is extreme) is that many CORR off road racing trucks use Holley carburetors. As a matter of fact...Ivan Stewart has started a new class of off-road where you are not allowed to have anything other than a Holley 650. These trucks are run VERY hard, over very rough terrain...and they do not miss a beat...Of course..they are not a "out of the box" carb...but most of the work done to them could be done by your average mechanic if given the proper instruction.
But with many of us...who do not race...and the very most horsepower possible is not necessary...it kind of falls under the category of "why bother"..because a quadrajet or 2100 will work fine with no mods.

 

I'm not Ivan Stewart, nor do I employ his mechanic. Maybe those guys can get the Holley to work, but what they do is worlds away from what i do offroad. Hands down a 2100 is superior to a Holley offroad, for Joe Average.. The 2100 is near bomb proof... As I said, I do have a 2 bbl Holley for cheap.. Ran great on pavement, but I hated it off road..

 

I can certainly appricate both sides of the Holly vs Motorcraft vs Rochester discussion, There is no doubt that some perform a little better than others in specific circumstances and I have had my share of minor difficulties with all of them.
I do think that the 2100 is a good simple setup for the average joe but I also know the Holly can perform well if properly calibrated for the application and the 4bbl Rochester is about as close as you can get to having the best of both worlds.
I think the two most common mistakes made are an application mismatch resulting in off spec calibration and general poor performance and using or attempting to use performance carburetors both 2 and 4 bbl that are just to large in air flow capacity and fuel mixing capability to provide the kind of smooth steady low and mid range throttle response that is desirable for the majority of off road conditions we encounter.

 

As was mentioned above...They will require some work, and if you're a bolt it on and go kind of guy, not looking for the most HP...then they are not for you...Just for reference sake...I AM an engine builder for guys like Ivan...I know what it takes to make a Holley run right off-road...and as I mentioned above...An average mechanic COULD do it...if he had the right instruction.
The reference to off-road racing was to point out that Holley's can and DO work when prepared properly.
Not to compare what average Joe Jeep driver does with what a professional racer does.

 

:iagree:

 

So...I was giving this topic some thought...and I did not want to seem as if I was trying to keep some big, super, Holley tuning trick secret. These tuning trick are defiantly not secret...Well...not in my line of work anyway. So, I figured I would share a few of them with you guys.
Keep in mind...These mods are more geared for you guys that already have a Holley. If you do not want to fix your problem by simply buying another carburetor...You can make your existing Holley MUCH more off road friendly. If you are currently without a carb (and do not want to use EFI) then I would suggest a quadrajet for a four barrel and a 2100 for a two barrel. Both these carbs are proven performers off road.

Now...if you have a Holley two or four barrel, here are a few things that any of you (I hope) can do.
First...let me give you a quick run down as to why a Holley does what it does when you start bouncing around...These are all simple and require a simple fix.
Number one problem is that the fuel which is in the fuel bowl starts sloshing around...This will cause that raw fuel to come out of your vent tube and straight down into the throat of your carb....This of course gives your engine many times more fuel than it needs...not to mention that it's just big drops of fuel and not atomized (so even worse)...Your engine cannot burn all this excess fuel...it blows black smoke, sputters and usually dies. Sometime you can keep it from dying if you stick you foot far enough in it...But this is normally not the best of solutions on a tight trail.
What to do to combat this particular problem is to try and prevent fuel from coming out the vent...Since you need the vent...you can't just plug it...but what you can do is make it more difficult for the fuel to come out of it and here's how.
Here is the vent of your average Holley.
You can see that it is short...If you increase the vent tubes height...then it will take more for the fuel to come out of it. For a two barrel carb, just extent it up like this.
For a four barrel carb, you can connect the front vent to the back vent.

This probably looks familiar to many of you...because Holley has done this very thing to it's "truck avenger" carbs. Let me assure you...this little trick was out MANY, MANY years before the truck avenger was even a thought.
Another way to help control this is what's known as a "vent whistle" Pictured.

This vent whistle extends the vent passage inside the float bowl...this makes it a little more difficult for the fuel in the bowl to find its way out the vent and every little bit helps.
Then there is this...which is referred to as a "fuel level control kit"..It's pretty much just a baffle to keep the fuel from sloshing around. This was originally developed to keep the jets in the fuel...but it also works to keep the fuel from coming out the vent. The less sloshing around in the fuel bowl, the better it works off road.

http://www.moroso.com/catalog/categorydisplay.asp?catcode=32034

There are a few more tricks to help keep the fuel from coming out the vent...but these are the biggies.



Another thing that makes fuel come out the vent is the float not being able to control how much fuel is coming into the float bowl. This happens when you start really bouncing around...As most of you know...the carb float shuts the fuel off from coming in the carb when the fuel in the bowl gets to a certain level. The float... floats (imagine that) in the fuel..The float floating puts pressure on a small valve (needle and seat) which closes off fuel from coming into the float bowl until the fuel in the bowl drops ...then the float follows the fuel down...releases pressure on the needle and seat and lets in more fuel (pretty simple really). When you start bouncing around a lot...the float bounces around too and it has trouble holding it's pressure on the needle and seat...So too much fuel is let in. This does a few things that make your Jeep go rich...but it also raises the level of fuel high enough that it will make it come out the vent easier...This is something we want to prevent...To prevent this, we use a spring loaded needle and seat. This coupled with the small spring under the side hung float (pictured)
will help control the float from erratic movement. The spring in the needle and seat helps keep the needle in the seat until it drops down enough to unseat it...then more fuel will come in...Essentially...it makes the needle and seat less sensitive to movement..Which is a good thing off road.

Since I am on floats and fuel levels...The standard practice for adjusting the float level on a Holley that is used on the street is as follows...With the car or truck on level ground, unscrew the "sight plug" (pictured)
You then adjust the fuel level until it is just at the bottom of that hole, put the plug back in and you are ready to go...Well...that does not really apply to us...unless you bought your Jeep to drive around the street. You want to adjust your fuel level lower than that...Most guys do this by running the float down a little with the sight plug out...Then shake the Jeep back and forth a little. When you can make fuel slosh out the sight hole by shaking it around...it's pretty good...I know it's not the most scientific thing...but it works and that's really what counts after all.

The level of the fuel in the float bowl can also be controlled better by regulating fuel pressure...I know that most of us just bolt on a carb...hook up the fuel line and hit it...This puts you fuel pressure anywhere from 4 to 10 pounds (normally in the middle of that). That works...but like I said before...every little bit helps...So you get yourself a fuel pressure regulator and a little in line fuel gauge...On normal driving...you can just keep it around 4 to 5 pounds...When you know you are going to be off road and doing some bumbling around...turn the regulator down so you only have about 2 pounds fuel pressure...This makes all the difference in the world when controlling the amount of fuel let into the float bowl. This of course is not recommended for wide open throttle for long periods of time with a large cube motor...because it will starve it...but it will work great otherwise. There is also a fuel pressure regulator that works off of engine vacuum...The idea here is that it only gives you about 1 pound of fuel pressure at idle and increases fuel pressure as you engine needs it...they work pretty slick.

There is another issue when dealing with fuel control and a Holley...and that is that when tipped at a severe angle...fuel can come from the fuel wells (what the jets sit in) and dribble out the boosters (pictured).

This CAN be dealt with...but it's not run of the mill kind of work and will not be a huge problem if left alone with no mods...So I will leave that one out.

Anyway, I would like to reiterate what I said at the beginning of this...There are carbs that need none of this work to run off-road...but if you want to keep your Holley...then this is how to do it.
There...now you can get a job as a mechanic for Ivan Stewart.

 

Very interesting reading!! I had a Holley 390 on my Clifford intake. That thing flew on-road, But not much good off-road, So I switched to the 2100, This one Rocks on the rocks!! I kept my Holley though because it was noticable faster than the 2100. I might have to start fiddlin with the Holley agian...
Thanks!

 

mcgillacuddy, where can the vacuum regulator be bought at? i have looking for one for quite a while.

 

Well...they certainly are not as easy to come by as they used to be (which I am sure you found out).
As far as I was know...they guy who made the "cagle fuel pressure regulator" passed away a few years ago and the remaining family decided not to continue his product. I'm not sure if that is true or not...just something I was told. Either way...the Cagle is becoming harder to get ahold of...but they are out there...Keep your eye on Craig's list and e-bay...they turn up every now and again. I do have a number of the family of the man who made the Cagle regulator...I was told they still have some...So you might give them a try (213) 377 7501....If you absolutely cannot find one anywhere...I could build something like it with a few mods to a boost sensitive reg (for turbos).

 

Interesting mcgillacuddy, I did a few of the mods mentioned. I extended the vent, and lowered the float level.. The rest of the stuff is new to me. But, overall for the wheeling I do the 2100 works better with no mods.. If I had had this info at the time I mighta been able to make the Holley work..

 

:tea: Having a big family with a broad range of experience and ideas is a good thing, I took some notes too