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  #21  
Old 03-20-2022, 06:39 AM
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stonybrookpictures stonybrookpictures is offline
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79 Wagoneer MPG

AMC 401, Quadratrac, 35" tires, 65 Mile trip, 70 MPH, 10 Gallons on the dot.......
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  #22  
Old 03-28-2022, 08:26 PM
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sierrablue sierrablue is offline
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Daily driving the '71 I've been having similar thoughts, and here's what I've gathered from some driving and reading a bunch of forums and talking to family about it:

The top thing is driving style, of course. Easy acceleration to start with will do wonders for mileage. I've also started popping it into N on the way into town, and putting it back into gear around 30, 35 (3.50s, 225/75r15s, and an auto that happens to be about the point where the RPMs aren't much above idle). If your neutral starter safety switch is lined up right (or with a stick simply pushing the clutch in) you can shut it off and get every last bit of mileage out of it. Also aerodynamics start coming into play right around 60 mph, so keeping it right around 60 in top gear is the peak mileage point, especially with a brick like a FSJ. So 55-65 is generally the recommended cruising speed.

As far as carbs go, the Edelbrocks and Qjets (more the Qjets) tend to get the best mileage from what I can tell. The Edelbrock would probably be the way to go with that manifold; it's easier to tune and already square bore. The advantage of the Qjet is that it has smaller primaries, and thus smaller venturies, which increases the pressure and thus makes for better metering. But the Edelbrocks still have metering rods and with the tuning kit it's pretty easy to get them dialed in. I just put a Qjet on and am working out the kinks...we'll see if it does any better for mileage than the Edelbrock did. But on my intake it's supposed to have a Qjet because it's a Buick 4-barrel.

Trannies tend to be expensive and need adapters for these rigs, but if you get a 5-speed in there, you can short shift it, the clutch allows zero slip (if it's good and let out), and they're lighter than an automatic.

The other thing I didn't see listed here was aero. I know these are massive bricks, but little things can help. Air dams are pretty easy to make if you don't have one, and those can help. Removing roof racks (a non-issue on J trucks)(well, most of them), big clunky mirrors, spoilers, and blocking off holes in the grille you don't need for cooling will also help the air go around the Jeep, thus allowing cleaner flow and less resistance. Other things that could potentially help with flow; all season tires (rather than the very square all-terrains), and theoretically keeping it washed and waxed can help...not sure how much that is helpful and how much people just like their rigs to look pretty, but there's that.

I've read that with the AMC V8s the 401s actually tend to get better mileage than the 360s. The '88 with 3.50s, 31"s, and the .060" over 401, headers, 3" exhaust (2.5" Y-pipe), and TBI would pull 18 on the first half of the tank, and about 12 on the second half, averaging about 15. I know, you said that's not the route you're planning on going at this point, but...

Oh, if you're running oversized tires and the speedo if off, you also need to add the 10% or so to the number of miles indicated, so you may be pulling better mileage than you think.

Currently I'm trying to smooth out my driving, utilize N a lot, etc. I'm getting a vaucuum gauge, too, so I'll be able to see how I'm sitting at cruise and good feel for my mileage at any given point. I found last year that more timing got me better mileage, too. But I'm running 3.50s and 225/75s as previously mentioned, with locking hubs. I also have the roof rack on, and I actually opted to stick with my heavy steel wheels. While they're harder to get rolling, once they're rolling they have more momentum (and it's not a dead weight; it's a spinning weight), and they allow me to run hubcaps that flow the air more cleanly. Other things affecting mileage for me is winter gas and cold temps (we're finally getting there though). Between it getting warmer and being smoother I went from lower 12s tops to upper 13s, and I could still be smoother. The last tank was 12.77 something, but then I spent a lot of time not going anywhere trying to dial in the Qjet. If I take the time and seal up my gas tank it'll probably go up too...60 is right around 26-2700 RPMs for me. Anyway sorry for the book. Hopefully it's a helpful book, at least.

I'm probably the only one, but I've been wanting to do an EV conversion on one of these...I've figured out how to get a reasonable setup for under $20 grand, which sounds like a lot, but in purely oil and gasoline (averaging $3.50 a gallon and 12,000 miles a year) it should pay off in less than 5 years. Plus no maintenance and all of that good stuff
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Current Rig:
'71 Wagoneer (DD)
B350/TH400/D20
open knuckle D44 front (disc brakes)
6-lug conversion rear
http://www.ifsja.org/forums/vb/showt...79#post1734879

Previous Rig:
Tan '88 Grand Wagoneer
.030 over 401, TBI, headers
3" exhaust
31x10.5s
2" rear lift blocks
custom headliner
http://www.ifsja.org/forums/vb/showt...77#post1734777

"The engineering side of me says that it's more than strong enough. The redneck side of me says that it's going to fall apart and I need to beef it up."--somebody I know
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  #23  
Old 03-30-2022, 05:23 PM
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timwiller timwiller is offline
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Smile holy grail of mpg??

my little 304 with t-18, 60mph, no headwind = 10mpg.


...try to drive downhill a lot.
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  #24  
Old 04-01-2022, 08:34 AM
'89_Wagon '89_Wagon is offline
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SierraBlue, it's impressive your '71 is your daily! Way to go!

That's a lot of work to save on gas and if prices go down again.... that $20k swap cost break even point will stretch out a few more years. Better to spend $5k or less on a manual civic hatchback from the early 2000's or other small car with a manual. You'll get you money back far faster with one of those. My wife was able to squeak 50-60 mpg on a regular basis from one of those last time gas was $4 a gallon.

Now, if you want to do the EV swap for fun, totally fine by me.

Also, just to nick-pick... you need to factor in the cost of electricity for the EV conversion... which the Wag will use A LOT of. There's no way around it... it takes a lot of energy to get our FSJs moving and keep them moving.
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  #25  
Old 04-01-2022, 06:39 PM
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sierrablue sierrablue is offline
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Talking

Quote:
Originally Posted by '89_Wagon
SierraBlue, it's impressive your '71 is your daily! Way to go!

That's a lot of work to save on gas and if prices go down again.... that $20k swap cost break even point will stretch out a few more years. Better to spend $5k or less on a manual civic hatchback from the early 2000's or other small car with a manual. You'll get you money back far faster with one of those. My wife was able to squeak 50-60 mpg on a regular basis from one of those last time gas was $4 a gallon.

Now, if you want to do the EV swap for fun, totally fine by me.

Also, just to nick-pick... you need to factor in the cost of electricity for the EV conversion... which the Wag will use A LOT of. There's no way around it... it takes a lot of energy to get our FSJs moving and keep them moving.

Thanks It's not perfect, but it'll get me anywhere I need to go, any time of year, and still beat a lot of new stuff of cars off the line...but hey we're talking mileage here And to be fair, it's from OR, so little to no rust (and PO resprayed it), and I've replaced some part of pretty much everything related to the engine.

I know, not the best EV conversion. I mean, the ultimate EV is something like a GT40; light and extremely aerodynamic, but designed for some level of structure (I mean, 427 big block...). But much like everyone on here, there's a certain draw to these rigs, and they're so practical (minus maintenance $). And it's super capable; with the all seasons and no lift I can get it pretty much anywhere without damaging the body, and also without getting stuck. I realize it's not the best canidate, but I could do a lot worse too. So I totally get it, and I don't anticipate anyone else on here going that way, but hey, every last bit counts. I will also say that gas prices were slowly on their way up before Russia made their move...so even if they're back down to $3.50 when things settle back down, we don't have an unlimited oil supply and we can't plan on the prices going down much again. Just my .02 though.

Sorry Chad, didn't mean to hyjack the thread or anything. One other thing to help mileage is a vacuum/"ecogauge" as Bosch labeled it. It shows you when you're on the gas really hard and might not know it, so it helps some if you pay some attention to it.
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Current Rig:
'71 Wagoneer (DD)
B350/TH400/D20
open knuckle D44 front (disc brakes)
6-lug conversion rear
http://www.ifsja.org/forums/vb/showt...79#post1734879

Previous Rig:
Tan '88 Grand Wagoneer
.030 over 401, TBI, headers
3" exhaust
31x10.5s
2" rear lift blocks
custom headliner
http://www.ifsja.org/forums/vb/showt...77#post1734777

"The engineering side of me says that it's more than strong enough. The redneck side of me says that it's going to fall apart and I need to beef it up."--somebody I know
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  #26  
Old 04-03-2022, 07:42 PM
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mrtazwrench mrtazwrench is offline
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Not a big deal, I just know I'm not going EV as my J20 is just a summertime toy. I do have a Wagoneer with an LS in progress I just need to get back on that and push to get it done.
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"Let's see that Red Blue Green **** sucker build one of these without duct taping it together!"
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83Cherokee WT
82J20
Parts vehicles: 1.5 Wags, 3.5 J20's, 1 J10 1 J300
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  #27  
Old 04-03-2022, 08:37 PM
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backroadin' backroadin' is offline
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Location: Vermont
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I second the qjet, great carb for economy with the small primariies and vacuum secondaries. I would at least go with a carb with vacuum secondaries.

Good tire pressure. I went from 32 bfg at's to 33 mud terrains and lost about 2 mpg or so. It's not my DD, so I was going for looks.

Install manual hubs if you don't already have them.

If I was to spend any money on trying to get better mileage, besides the carb I'd probably change to 4.10's if you're set on those tires. A tranny swap would be spending too many dollars to save pennies, but if you did the gear swap yourself, it'd be less dollars. Don't go freeway speeds and drive by the tach and vacuum gauge.
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"Roads? Where we're going we don't need roads." -- Dr Emmett Brown

"When this baby reaches 88 miles per hour, you're gonna to see some serious sht!"

73 Wagoneer - 4.6L Stroker (yeah baby!!) t176/d300, 3.73's, 33" muds, 4"spring lift, 2" body. Offy dualport w/ Quadrajet, pertronix, flowmaster.
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  #28  
Old 04-23-2022, 07:51 PM
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sierrablue sierrablue is offline
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I ran into one more thing with mileage here, I'm not sure how interested you guys are.

I discovered about a week and a half ago that my left front brake caliper was dragging. When I pulled the wheel, I discovered that the caliper wasn't free to move--if I stepped on the brakes, I literally could not make the rotor turn by hand (after lifting off). I had to break it loose with a mallet, and even then it was clearly too tight. Taking it apart, I discovered that the bushings couldn't move freely within the caliper. I wound up pressing them out, and cleaning the bushing surfaces, as well as the corresponding rubber insulators, using steel wool. Then using one of the bolts that holds the caliper on, I put axle grease on those surfaces once they were cleaned. I put everything back together, and on the last tank I pulled 15.23 mpg, still on winter gas I'm pretty sure. And I was harder on it than I'd been trying to be, so I was expecting somewhere in the 13s. So check your brakes, make sure they can move properly, and make sure the rears are still in alignment. One more thing to keep in mind, that will make a big difference.
__________________
Current Rig:
'71 Wagoneer (DD)
B350/TH400/D20
open knuckle D44 front (disc brakes)
6-lug conversion rear
http://www.ifsja.org/forums/vb/showt...79#post1734879

Previous Rig:
Tan '88 Grand Wagoneer
.030 over 401, TBI, headers
3" exhaust
31x10.5s
2" rear lift blocks
custom headliner
http://www.ifsja.org/forums/vb/showt...77#post1734777

"The engineering side of me says that it's more than strong enough. The redneck side of me says that it's going to fall apart and I need to beef it up."--somebody I know
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  #29  
Old 04-24-2022, 05:39 PM
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babywag babywag is offline
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Posts: 10,106
caliper kits are like $5
gets a guy new bushings/pins/etc.
rarely replaced during brake jobs but is required imho
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88 GW, 67 J3000, 07 Magnum SRT8
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  #30  
Old 04-25-2022, 01:08 AM
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FSJunkie FSJunkie is offline
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Mine gets 11 mpg at 75 mph and 14 mpg at 65 mph. That tells you the whole story right there. It tells you that the biggest reason fuel economy sucks in these Jeeps is their aerodynamics. They fight the wind and the faster you go the worse it is.

Want to save gas? Drive 55 mph.

How much gas can you buy with the amount of money that it would take to modify the Jeep for better fuel economy? It would only be marginally better fuel economy at that.
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  #31  
Old 05-17-2022, 06:21 AM
'89_Wagon '89_Wagon is offline
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Do those OEM spoilers do anything for gas mileage?

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  #32  
Old 05-17-2022, 08:58 AM
sierrablue's Avatar
sierrablue sierrablue is offline
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Quote:
Originally Posted by '89_Wagon
Do those OEM spoilers do anything for gas mileage?

Nothing for mileage (sticks up into the wind which adds drag). But hey, you won't suck exhaust into the rear window with it.
__________________
Current Rig:
'71 Wagoneer (DD)
B350/TH400/D20
open knuckle D44 front (disc brakes)
6-lug conversion rear
http://www.ifsja.org/forums/vb/showt...79#post1734879

Previous Rig:
Tan '88 Grand Wagoneer
.030 over 401, TBI, headers
3" exhaust
31x10.5s
2" rear lift blocks
custom headliner
http://www.ifsja.org/forums/vb/showt...77#post1734777

"The engineering side of me says that it's more than strong enough. The redneck side of me says that it's going to fall apart and I need to beef it up."--somebody I know
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  #33  
Old 05-17-2022, 11:02 AM
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devildog80 devildog80 is online now
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It forces air down the back of your rig, yes to keep exhaust fumes from swirling in behind you, keeps the back of your truck a bit cleaner and cuts the drag a little.
So multi purpose function for aerodynamics of the bricks' backside
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1984 Grand Wagoneer, 401 ci (.030 over), A727 auto, Selec-trac NP229, AMC 20 REAR - D44 FRONT (6 LUG) WT 3.31, 4 in arch spring lift (not a woody - think it was ordered new without, 1984 the only year it was an option)
Rather be driving, than waiting for modifications!
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  #34  
Old 05-17-2022, 09:04 PM
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backroadin' backroadin' is offline
350 Buick
 
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Location: Vermont
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Quote:
Originally Posted by FSJunkie

How much gas can you buy with the amount of money that it would take to modify the Jeep for better fuel economy? It would only be marginally better fuel economy at that.
Well said - actually that whole post was spot on.
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"Roads? Where we're going we don't need roads." -- Dr Emmett Brown

"When this baby reaches 88 miles per hour, you're gonna to see some serious sht!"

73 Wagoneer - 4.6L Stroker (yeah baby!!) t176/d300, 3.73's, 33" muds, 4"spring lift, 2" body. Offy dualport w/ Quadrajet, pertronix, flowmaster.
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  #35  
Old 05-20-2022, 02:13 AM
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Brynjminjones Brynjminjones is offline
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To add my 2 cents - the best thing for MPG I did on my 1991 Grand Wagoneer was reinstating some of the factory vacuum junk. I spent a long time tuning the carb, plus sorting out the EGR.

With my rebuilt 360 bored .030" over, I get around 12 MPG driving hard on twisty, hilly roads.

Lots of short journeys around town obviously lowers this (to around 10 MPG), but equally I can get up to 14-15 MPG on a long trip, varying between 65-75mph.

I never expected to be able to beat the EPA estimates so easily, but the thing runs great!
The best part is that this was all free, except my time.
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  #36  
Old 05-20-2022, 12:10 PM
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devildog80 devildog80 is online now
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That is what loving our FSJ's is all about

Quote:
Originally Posted by Brynjminjones
To add my 2 cents - the best thing for MPG I did on my 1991 Grand Wagoneer was reinstating some of the factory vacuum junk. I spent a long time tuning the carb, plus sorting out the EGR.

With my rebuilt 360 bored .030" over, I get around 12 MPG driving hard on twisty, hilly roads.

Lots of short journeys around town obviously lowers this (to around 10 MPG), but equally I can get up to 14-15 MPG on a long trip, varying between 65-75mph.

I never expected to be able to beat the EPA estimates so easily, but the thing runs great!
The best part is that this was all free, except my time.
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1984 Grand Wagoneer, 401 ci (.030 over), A727 auto, Selec-trac NP229, AMC 20 REAR - D44 FRONT (6 LUG) WT 3.31, 4 in arch spring lift (not a woody - think it was ordered new without, 1984 the only year it was an option)
Rather be driving, than waiting for modifications!
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  #37  
Old 05-20-2022, 04:57 PM
conehead conehead is offline
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Don't mean to brag but my 1987 Grand Wagoneer is getting 16-20 mpg at 65-70 mph but I have made some changes. 360 with Howell Fuel injection, NV 4500 5-speed and front axle locking hubs.

Last edited by conehead : 05-20-2022 at 05:05 PM.
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  #38  
Old 05-20-2022, 05:00 PM
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devildog80 devildog80 is online now
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Nice setup
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1984 Grand Wagoneer, 401 ci (.030 over), A727 auto, Selec-trac NP229, AMC 20 REAR - D44 FRONT (6 LUG) WT 3.31, 4 in arch spring lift (not a woody - think it was ordered new without, 1984 the only year it was an option)
Rather be driving, than waiting for modifications!
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  #39  
Old 05-23-2022, 08:00 AM
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Mikel Mikel is offline
 
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I put an O2 sensor in my 1966 Oldsmobile so I could tune the carb more accurately. I played with the power piston spring in my quadrajet and now it runs leaner at light throttle (15-15.5:1 cruising) and gets richer quickly under heavier throttle. I went from 11MPG highway to 14 MPG.

I was going to get an EFI unit, but I'm having second thoughts. In the end, it's very difficult for a carburetor to leave you stranded. Money very well spent on the O2 sensor.
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Last edited by Mikel : 05-23-2022 at 08:16 AM.
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  #40  
Old 05-23-2022, 11:21 AM
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devildog80 devildog80 is online now
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Agree with you 100%

And EFI will rarely improve MPG, only lets your old vehicle respond like a newer one, to turn key and go. No more warm up time for choke etc, and then "where do I put the computer screen" becomes an issue!

I'm carbing with you
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1984 Grand Wagoneer, 401 ci (.030 over), A727 auto, Selec-trac NP229, AMC 20 REAR - D44 FRONT (6 LUG) WT 3.31, 4 in arch spring lift (not a woody - think it was ordered new without, 1984 the only year it was an option)
Rather be driving, than waiting for modifications!
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