Anyone know how to get better Mileage

[BajaEdition]

I have wheeled so many 4 bangers, and properly set up they wheel as well as any 8, well maybe not in sand or mud.
remember most wheeling is about torque, if you need more torque get lower gears for the tcase.

 

[mredjeep]

I would agree ..the 4's and 6's do well off road. I head up North in California to get to the Rubicon, the small motors have a tough time keeping up on the highway. The V8 is Great. I do see that some guys have the Chevy 350 swap and Do get much better mileage. It does depend on How deep the pockets are.

 

[TDHofstetter]

Looking to get better mileage on an OEM AMC 304 2bl carb..

Any ideas on this ??

Throw it in the back seat of a Toyota Yaris.

More realistically, as a "driver", put skinny little hard tires on it like the factory did. Figure out something to do about that billboard windshield 'cause its aerodynamic design is HIDEOUS. Take any lift kit you may've installed back off to set the Jeep back down where it at least pretends to hide the axles from the airstream. Add an air dam to finish the hide job.

Really, a 2-barrel AMC 304 should get you better gas efficiency than that - even in a Jeep. Part of the problem is that they're so fun to drive with a AMC 304 that it's really HARD to correct operator error.

One thing you can do - it's a cheap bolt-on - is to install a diffuser screen under the carburetor. Yeah, it helps. I used to pull 20mpg out of my Rebel MACHINE with the 390/4v/T10.

A good solid tuneup helps, sometimes in a VERY large way.

 

[mredjeep]

Never heard of a diffuser screen. Any info on or part #

 

[TDHofstetter]

I'm shocked - I've been digging around the 'Net looking for the dang things, and they seem to have ceased to exist. They USED to be a common item marketed under the Mr.Gasket name, hung on the wall in every parts shop. If they still existed, they'd have been right here where they belong:

Mr. Gasket :: Products

Here's what it was: A diffuser was an extra-thick (about 1/4" thick) carburetor gasket with a stainless-steel screen sandwiched between two layers. The screen was domed in the two venturi holes to clear the butterflies. As the gas/air mixture passed through the screen, it broke up the flow & did a much better job of mixing. Worked like crazy.

Heck, if they're not out on the market now, I'll start making & marketing the dang things - they're THAT good!

I hadn't realized before tonight that the CJ2a actually came with one from the factory - that was one of the first hits in my search for 'em tonight. They were extensively used in prop aircraft, too.

 

[mredjeep]

Thanks Tim for the advise

 

[BajaEdition]

Kinda like what a tornado does but on the other end of the carb?

 

[TDHofstetter]

Sorta' kinda'. Does the Tornado actually work? Seems like that swirling effect might be almost completely gone by the time the air actually sees fuel, but it might still be there.

An under-carburetor diffuser, on the other hand, breaks up the droplets of fuel for sure for sure. Kinda' like throwing a tomato through a chickenwire fence.

I was thinking, during my last cigarette break, that a fella could use a completely flat stainless screen instead of a reverse-domed one if a thick adaptor plate was installed on top of it to provide the butterfly clearance. That'd make construction a pile simpler.

 

[essexmo]

But it still would be a AMC 304 with a 2 barrel carb if youre gonna stick with it at least get an edelbrock 4 barrel manifold and a 4 barrel carb and invest in a better cam one that will give you a better economy plus a set of headers This might bring you up to 17 or 18 miles per gallon as long as you dont have a lead foot a small block chevy would give you 20 but its your call

 

[essexmo]

I'm shocked - I've been digging around the 'Net looking for the dang things, and they seem to have ceased to exist. They USED to be a common item marketed under the Mr.Gasket name, hung on the wall in every parts shop. If they still existed, they'd have been right here where they belong:

Mr. Gasket :: Products

Here's what it was: A diffuser was an extra-thick (about 1/4" thick) carburetor gasket with a stainless-steel screen sandwiched between two layers. The screen was domed in the two venturi holes to clear the butterflies. As the gas/air mixture passed through the screen, it broke up the flow & did a much better job of mixing. Worked like crazy.

Heck, if they're not out on the market now, I'll start making & marketing the dang things - they're THAT good!

I hadn't realized before tonight that the CJ2a actually came with one from the factory - that was one of the first hits in my search for 'em tonight. They were extensively used in prop aircraft, too.

i think they were called an atomiser

 

[Cheepjeep85]

I'd recommend a good tune up first, some quality plugs like those diamond fire,
change your fluids, check your air pressure. Search out the fuel additive thread on here.
The TBI swap would be good and your reliability goes up.

Other than that anything else added is kind of a waste unless your changing it for
another reason.

do this especially i can't say enough good things about the E3 diamond fire plugs they got me 4 mpgs in my 4.3 v6 s-10 when i had it. i had a slight miss at idle since i bought the truck in 2002 i put the E3s in it after trying several other plugs and the miss disappeared. i am firm believer in these plugs they are just a little expensive at $7 a plug

 

[BajaEdition]

Sorta' kinda'. Does the Tornado actually work? Seems like that swirling effect might be almost completely gone by the time the air actually sees fuel, but it might still be there.

An under-carburetor diffuser, on the other hand, breaks up the droplets of fuel for sure for sure. Kinda' like throwing a tomato through a chickenwire fence.

I was thinking, during my last cigarette break, that a fella could use a completely flat stainless screen instead of a reverse-domed one if a thick adaptor plate was installed on top of it to provide the butterfly clearance. That'd make construction a pile simpler.

We dynoed a Tornado back in my SCTA days and yes they do work, there are so many things that can do this though, we installed trip fences in one motor right before the valves and got a great increase, problem was the machine would eat those fences about every third run and destroy the heads. We messed with porting techniques to leave increasingly rough area around the end of the intake manifold, which had mixed results. We tried quite a few things but I believe trip fencing got us the best results. Seems it agitated the air so much at the last second more fuel would come out of solution into gas than anything else we ever tried.
I got the idea from reading radiator tech articles, it seems the very worse way to face a radiator is the way we do conventionally. What we do is best for any vehicle that is going to be running while not moving down the road, or going at slow speeds, and using a fan to pull air through the fins is also very ineffectual at all but slow speeds, However because of the way we use the common auto, we need it this way. What the problems are is a multiple array to cure, one of the biggest id the fact that a small amount of air remains as a thermal shield around each fin If you were to turn the radiator 90 degrees to the airflow and add a trip fence in front of it the turbulent air you creates rips this barrier away and the ventral effect of the passing air draws coll air through the fins and actually cools the coolant better than our method at slower speeds. Race cars and bikes use this tech, but they are moving 98 percent of the time.
Anyway, I just thought I would comment on the questions about them working, you see having access to a dyno any time I want, although my computer in there is over 6 years old, I try out stupid ideas I come up with all the time. Like the time I tried to temperature control intake manifolds, tried differnt techniques for over 2 years with mixed results.

 

[TDHofstetter]

They're only stupid ideas if they're poorly thought out & don't work. Or worse yet - if they make a known problem worse.

One thing I don't think anybody's touched upon yet is the camshaft - a good low-lift, low-duration low-speed camshaft can help quite a lot, too, if it's timed right for fuel economy. Fortunately, a low-lift, low-duration camshaft is ALSO very good for the kinds of things lots of folks do with their Jeeps.

 

[mhubacek]

The only way I know of to improve gas mileage is to find a way to make it back and forth from your destination going downhill both ways!

 

[BajaEdition]

best way to get more gas ileage out of that jeep would be to return the lift to stock and put in stock tires.
besides that tuning the gear ratio to the tires and a good tuneup
after that go for all the gas saving devices you can, but remember we are working with technology that is considered antique and unless you want to upgrade, there is not a great bit of stuff you can do. the problem is the auto industry recognized that a closed loop fuel injection system was the way to go, and went that way. carburetor tech went to getting more power. So I guess the answer is........... spend money.

 

[BajaEdition]

actually, I dis agree with my last post

what I think is a lot of guys buy a CJ thinking it is a quick and cheap way to go wheeling, and they are so wrong.
I could get a used street queen TJ and put a grand into it and be a better wheler than a CJ, 2500 and I can get it to go places that few will want to go.
And I can get that used TJ for around the price of a CJ.
CJs are antique vehicles and need a lot of upgrades to be made madern, brakes, springs, fuel systems, rebuild ancient drivetrain, before you know it you have 15 grand into them. spiining a pinion dhaft and you will upgrade to modern and have to replace a driveshaft yoke, the list goes on.
I think a new Jeep would be cheaper that wheeling a classic. But opinions are like a$#*%&^s.

 

[John Strenk]

On an odd note, JK are tilted with the front lower than the back. People who put lift kits on a JK to even them out loose 2 mpg.

On a side note, I get 19-20mpg with my CJ but it is lighter (fiberglass tub and fenders) and has AT tires at 35 PSI. I rarely take it over 45 mph also.

 

[TDHofstetter]

actually, I dis agree with my last post

what I think is a lot of guys buy a CJ thinking it is a quick and cheap way to go wheeling, and they are so wrong.
I could get a used street queen TJ and put a grand into it and be a better wheler than a CJ, 2500 and I can get it to go places that few will want to go.
And I can get that used TJ for around the price of a CJ.
CJs are antique vehicles and need a lot of upgrades to be made madern, brakes, springs, fuel systems, rebuild ancient drivetrain, before you know it you have 15 grand into them. spiining a pinion dhaft and you will upgrade to modern and have to replace a driveshaft yoke, the list goes on.
I think a new Jeep would be cheaper that wheeling a classic. But opinions are like a$#*%&^s.

I've got three CJs, two '5s and one '7. I've got just about a thousand dollars in each one. Two of 'em are roll-ready, and the third (one of the '5s) is undergoing a frame-off. The '7 is a regular driver, registered & insured & inspected.

All three should still be driving just fine in 2025, after that TJ has been crushed to make a new Liberty because ya won't be able to buy electronics for it any more.

I'm not saying anyone else should conform to my set of ideals - just voicing another opinion among many.

 

[IOPort51]

On an odd note, JK are tilted with the front lower than the back. People who put lift kits on a JK to even them out loose 2 mpg.

On a side note, I get 19-20mpg with my CJ but it is lighter (fiberglass tub and fenders) and has AT tires at 35 PSI. I rarely take it over 45 mph also.

Do you think the extra 2 MPG is from reduced wind resistance of because it is rolling down hill all the time?

seriously; I never noticed that, how much lower is the front??