is 12 mpg possible for me?

[kreb]

i just can't beat 8mpg. those with the 2bbl 360 do you have any suggestions. motor is new with summit cam, holley rebuilt 2150, MSD/ TFI ignition. she has good performance but i figured after all this i could get better mpg. i have 32's with the 3.31 gears. i did the lightfoot technique with 2 different tanks full of gas but nothing. all the vacuum hoses are new and seemed to hooked up correct. i am going to reverify this in the near future. i sprayed carb cleaner under the hood to see if there are any leaks but nothing.

my drives are mostly street(5-15minutes) with little highway use. new fuel pump. i am thinking of trying different plugs and the plug wires are msd 8mm with little than 10000 miles. the current plugs have a good tan color to them.

i know our rigs are gas guzzlers but i thought i could at least get stock mpg. are the lift and tires creating to much drag? thanks

benjamin

[ October 17, 2002, 01:01 PM: Message edited by: kreb ]

[Green Giant]

Pry out one or two of those pesky Hondas that get stuck in the grill and see if it helps. :D

[Joe H.]

I get 12 mpg reliably, most I've ever seen was 14. I think with a 4" lift and slightly larger-than-stock tires you may not be able to do too much.

[mtn goat]

Remember thats stop and go....you will be up to about 15 on the highway...which is **** good for these beasts

[mtn goat]

oops, i thought you said you were getting 12. sorry. Get a 258!!!! I just beat displacement in one area anyway..

Sorry, carry on folks.

[kong]

It's definitely the stop and go traffic. Your motor is probably just getting finished warming up when you stop driving it. If you let it sit and warm up, that's eating away into the mpg too.
I read something on the FSJ-List about people air-ing up tires to rediculous psi's (40's and 50's) and getting lots better mpg.... worth a try.

Kong

[coolram]

You should do better than 8mpg in town but not better than 12mpg.Under 45-50 the lift doesn't really come into play.The 32s would raise(lower numerically)your gearing so you would have to step a little more in on acceleration.Have you adjusted your carb with a vaccuum gauge?What type of muffler/age,cat converter/age?

[letank]

>>>It's definitely the stop and go traffic.<<<

I'll second that... when i had to drive less than 10-15 min my mileage went from 11 city to below 9..... and i can get about 15 to 17 hiway, and i have 2.79

Michel
74 wag

[Don S]

Originally posted by kong:
It's definitely the stop and go traffic. Your motor is probably just getting finished warming up when you stop driving it. If you let it sit and warm up, that's eating away into the mpg too.
I read something on the FSJ-List about people air-ing up tires to rediculous psi's (40's and 50's) and getting lots better mpg.... worth a try.
Kong..
Kong said it right. I run 40 psi in the rear and 42 in the front in my 31x10.50s With your type of driving I would use a 195 degree thermostat to help keep that gulf moisture out of the oil and for better combustion. I would (and do) use an upper-lube to reduce friction when the rings have set. Click the link below
FUEL TANK ADDITIVES
http://groups.msn.com/ATexasOklahomaJeepClub/ouraycotopic.msnw
I would look for 9.5 mpg for driving in Corpus…
Good luck… CUL… ;) ds..
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[kreb]

mtn gt- i just need those extra two cylinders. have no reason just need 'em

coolram- 2.5 exhaust, magnaflow 3in muffler, no cat. have all cto's and egr, two new cto's and new egr. the carb has not been adjusted with vacuum gauge. plugs look good and she has plenty of power. but i have to let her warm up in the mornings to run good.

kong- psi is 32 i believe. i worry about the tires wearing funny if i go higher, i will look into that though.

one thing that might be mentionable. the phenolic spacer i have is solo. it does not have cardboard thick spacer on it. the piece was used because the oem one was cracked. but it is thicker the than the oem but not as thick as the oem one with cardboard spacer.

benjamin

[joe]

Originally posted by kreb:
are the lift and tires creating to much drag? thanks
benjaminI don't know how difference it makes in town at 25mph but the increased turbulance under the rig from the lift will hurt your mpg's at hwy speeds.

[Stuka]

I get 12mpg with a edlebrock intake and 600CFM carb. You sould get WAY better then that I would think. Either its running rich or you got a really heavy foot. I live in steep terrain, arent any flat roads here really.

[rawdave]

Eagle Research (http://www.eagle-research.com)

Try this place. I have several of his books already and as soon as my fuel injection is finished, i am going to start applying his technology to my jeep.

[buggy boy]

if u people get better then 12mpg on the highway, tell me the trick becasue that is all i get. I never heard of getting 15-17 mpg with a 360. Factory specs says they get 10 city and 13 highway. I am running all stock.

[kreb]

i am gonna air up and take a look at the vac lines. i still need to figure out my bad morning starts.

benjamin

[coolram]

Kreb have you tried adjusting your choke when the engine is cold?This could be your cold start problem(but don't get to carried away with the adjustment because you create driveability problems when she warms up if the choke doesn't open far enough),try using a 1/8" drillbit to set clearance between the airhorn housing and the back edge of the choke plate to start with.Turn your key on without starting and pump about 3-5 times(sets the linkage on fast idle)then crank.She should idle high and with a bump of the pedal idle down.Haynes and Chiltons give you more details but this should get you close.

[letank]

Buggy boy says:if u people get better then 12mpg on the highway, tell me the trick becasue that is all i get. I never heard of getting 15-17 mpg with a 360. Factory specs says they get 10 city and 13 highway. I am running all stock.

Well i am all factory specs..... off course with the oxygenated i do not pass 15.5.... and 55 or 65 does not make a difference nor does the load.... 1 person or 5 people with their gears

I have the 2100, pertronix ignitor, spiral wire lead, AC copper plug RN 12YC, TH 400 and QT with the overdrive... but that did not save me anygas, michelin LTX 235/75/15 at about 32 to 34 psi. regular oil and gas.... No A/C... rats that was hard on the way to Ouray

Cheers

Michel

[turtle jim]

When I bought my present wag(my daily driver),the PO said he never got less than 15 mpg.I thought to myself,yeah right.First few times I filled the tank it DID seem to be getting pretty milage,so I started to keep track.PO was right!!!!Once a week I take a short trip,120 miles,shop,and return.When I'm careful,I'll almost always get 16.5 mpg,never less than 15 mpg,and that's with AC and 75 mph.Once on a long trip,I got 17.96 on one tank.
I don't offer any explanation.Both previous owners were older,retired guys with no interest in off-roading or modifications.As far as I know the 360 and 4 barrel are completly oem.Also have th 400,q trac w/od,3.07s,235 tires.Odometer shows 36,000.Probably 136,000,maybe even 236,000.
That being said,I'm certain 15 mpg is a realistic,attainable figure for a fsj with a 360.

[reddog]

With 87 stock (except TFI - w/ about 40k miles) 3.31 gear, 30 X 9.5 tires I was getting upper 13/low 14 MPG highway if you try hard and use all that weight/momentum to you advantage. Have not checked since lift/tires.

Kerry

[buggy boy]

well, then what do i have 2 do 2 get 15 mpg? I have replaced everything possible and it still gets a high 12mpg. My only guess is that the engine is tired but she runs good and i get around 130 psi in every cylinder. What am i doing wrong. In 2 weeks i am moving, going almost 1000 miles and love 2 c me getting 15mpg on the highway!

[tuckers89GW]

I'm getting about 15 on the hiway with 130K on the clock and all stock. rebuilt carb this summer.

I do know that if I'm not driving on a trip, gas milage really goes down. I probably only get around 10 in stop and go driving at the best.

[joe]

Kreb, since you didn't swap axle gears and prolly not the speedo drive gear either...your speedo/odo will be off.
You're running about 10% larger tires so the speedo/odo will be reading about 10% low. If you've been checking mpg's at say 200 miles you actually went about 220 miles. If you've been getting 8.6 mpg re-figure it again with the added miles. You're actually getting into the 9's now and maybe even close to the 10's. Not terrible for a lifted rig. You're nearing the ballpark anyway of what you should be getting. smile.gif

[YAKFSHR]

just checked mine...12.041 mpg on the last tank. which just had the carb rebuilt and still runs like crap when cold. the fumes are down the power is up. just not fast idling when cold. i say you can get 12 or hopefully more.

[Maynard]

check your fuel line pressure, i believe that if its too high it will give you crappy mileage. i belive that it should be around 5 psi. i would check for sure since i only know half of what i am talking about :D

[kreb]

joe- are you just saying that to make me feel better. that is swell of you ;) . no the speedo or odo have been fixed to read properly. i am gonna take a trip in the next coming weeks and see what the actual mileage is using mapquest.com

maynard- i am not familiar with checking the fuel line pressure? how to?

thanks for the responses guys. keep 'em coming

benjamin

[joe]

Originally posted by kreb:
joe- are you just saying that to make me feel better. that is swell of you ;) Although what I mentioned above does affect mpg's and yeah...I guess I was tryin to make ya feel a bit better. ;) Since you already covered that but you do a lot of 5-15 min drives, you may just need to do an Italian tune up...balls to the wall up hill as fast as you can, as long as you can legally pull it off smile.gif

[Don S]

Originally posted by kreb:
i am gonna air up and take a look at the vac lines. i still need to figure out my bad morning starts.

benjamin..
kreb:...
When my ’81 acted like that it WAS the power valve draining the carburetor every night and fouling one spark plug.
Good luck… ;) CUL… ds..
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[kreb]

no fuel leaking from the power valve hose. but there is a thread right now on the board about the subject, i am gonna give it a read tomorrow. but just in case the jeep gods are reading i am so glad she is running. thanks

benjamin

[Ernzo]

]...you may just need to do an Italian tune up...balls to the wall up hill as fast as you can, as long as you can legally pull it off smile.gif ROTFL, and the best part is, IT WORKS!!

[ October 19, 2002, 10:49 AM: Message edited by: Ernzo ]

[CowKiller]

cleans motor out really good. nice black cloud out the pipe when i did it. lol

[maxrad]

My '83 WT gets a steady 14 to 15 mpg no matter how I drive it.

The few things that REALLY worked best to increase gas milage to this point was:

o replace your front hubs with manual, less friction, I got about a 2 mpg increase. (learned that tip here)

o fully synthetic oil, about 1 mpg increase.

o removal of all useless vacuum accessories & cto switches. (just configure your engine to use early '60's vacuum demands and your about right)

Hope this helps.

[buggy boy]

i also learned here in this forum that it is pointless 2 put on locking hubs because u never get ur money back in gas mileage for them. That is what i was told when i posted the advantages/disadvatages 2 locking hubs. Plus i was told that if u forget 2 lock themm and put ur transmission in 4wd, u can do some damage

[kreb]

the mpg is driving me crazy. i am just gonna have to start all over and recheck the fuel and spark systems to make sure everything is in order. when that infomercial for the tornado fuel saver came on i was close to ordering it, that is desperation. i would be so happy to get 10 regularly. but i think will look into adjusting the speedometer gear too.

benjamin

[Maynard]

to check the fuel line pressure, you need a vacuum gauge that can be used as a pressure guage, hook it up in-line and fire it up. now that i notice its a 91, you prolly have a return line so too much pressure prolly aint hurting you, but worth a check if you have the tools.