727 overdrive add on for MPG boost - 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 > Full Size Jeep Forum > 727 overdrive add on for MPG boost

SPARTAN LOCKERS are on sale BIG TIME at ROCKRIDGE 4WD!Ruffstuff XJ Unirail Channel Reinforcement....Shop Stuff to Complete the Job!

Reply
Unread 05-04-2013, 09:07 AM   #1
KC87Wagoneer
Registered User
1987 FSJ Wagoneer 
 
Join Date: Jul 2012
Location: kansas city, MO
Posts: 52
727 overdrive add on for MPG boost

I have been reading about the gear vendors 727 overdrive. I am guessing that there is no kit that can be purchased to add overdrive to my existing 727. Is this possible? The transmission was replaced only about 2,000 mi ago by the previous owner. I am trying to increase MPG so I am wondering if I can add overdrive without spending $2-3,000 on a new transmission.

I have a 1987 GW with a rebuilt 360 (800 mi ago) reman 727. Drivetrain is in good shape.

I have upgraded the ignition, rebuilt the carb and put in a K&N air filter and have increased MPG from 7.8 to 9.4. I want to get it up to the factory 12 or better. Next is all new vacuum components, new EGR, headers, muffler, cat and intake before I do anything more expensive like lockout hubs. Any advice would be welcomed but I would really like to know if the 727 can be converted without replacement.

img_3529.jpg  
KC87Wagoneer is offline   Reply With Quote
Unread 05-04-2013, 11:18 AM   #2
revelc
Registered User
1985 FSJ Wagoneer 
 
Join Date: Nov 2011
Location: Tyler, Texas
Posts: 663
You have a few options that are FAR cheaper than gear vendors. If you are up to it you can swap a 5.3 Chevy 4L80E combo that will double your MPG's. That swap can be had for around $3,500 if you find a wrecked truck, Youd just need a new radiator, custom mounts, and a T-case adapter or you can use the Chevy one. Or you can pick up a few MPG's by getting a 700R4 (not known to take much abuse) or the 4L80E with a standalone computer unit.

If your worried about expensive modifacations you chose the biggest wallet leech Jeep made. Sell it now if mileage is a concern.

I say this because the mods needed to yield better economy are not cheap. If you want more efficiency Id do the following. Upgrade ignition (check), install Edelbrock Performer with 4-BBL Carbof your choosing (They actually get better MPG if you keep out of the secondaries), Comp 260 cam kit it will remove the factory retarding and you'll actually unlock more power as well (you can use your stock valve springs or replace them), Doug Thornleys with 3" pipe, even using the stock manifolds and running a better flowing exhaust helps.

Lock out hubs are great, but the AMC 360 drinks gas regardless.
Your engine is an air pump. The more you do to help it breath, the more power it will produce with the same or less amount of fuel. Those mods will give you what will feel like a new motor. And they will help efficiency as well.

You can go a step further and just get a spare 360 and build it over time. Cores are anywhere between $100-$500 and all of those other mods won't cost near as much as the gear vendors. Then install a TBI from a Chevy and use the computer from the donor vehicle you snagged it from.

Its hard to push a brick down the road with a V8 and not expect it to drink like a freshman.
__________________
Wag Rebuilt 360, 260H, 727, Locked 44, AMC 20, 208, 31" M/T's, 4" Rustys, 2.5" Duals. SOON:SOA SF, 496, T400, Doubler, D60's, 37" M/T's <-TOY
Cherokee Rebuilt 360, 2" Duals, mostly stock. SOON: Hot Street 401, 4'' Rustys, 33" BFG A/T's maybe a T-case to get rid of Q-Track <-TOW RIG
revelc is offline   Reply With Quote
Unread 05-04-2013, 12:01 PM   #3
RockRollin
"Positive.....I think"
 
RockRollin's Avatar
1990 FSJ Wagoneer 
 
Join Date: Apr 2012
Location: Grand Haven Mi, USA
Posts: 1,083
Without changing the power band of the stock 360, chances are a 30% decrease in RPM will have you in and out of O/D, and laboring more to push the wind out of the way. I have de-smogged my 90, four barrel, mild cam, ignition upgrade, I am getting (avg) 13mpg over the last four tanks of fuel (I like the 4bbl sound however), and I'm not on roads over 65mph speed limit.
I would be interested in seeing what the mpg difference is between the Wagons with the 3:31gears and the 2:73.
When looking into the overdrive option myself the experienced users seem to agree "using O/D to reduce wear on the drive train=good idea, expecting great gains with O/D in mpg=bad idea". If running 4:56 gears, well yea
__________________
"I like fun" Edd
Clawed: 90GW, TFI, Streetfire, 3"lift all spring, 31"BFG ATs, working RKE, Edel2131, Holly 1850, mild cam,
05 Renegade OME 927, 947, top plate, JBA 4.5s
RockRollin is offline   Reply With Quote
Unread 05-04-2013, 12:17 PM   #4
revelc
Registered User
1985 FSJ Wagoneer 
 
Join Date: Nov 2011
Location: Tyler, Texas
Posts: 663
Quote:
Originally Posted by RockRollin
Without changing the power band of the stock 360, chances are a 30% decrease in RPM will have you in and out of O/D, and laboring more to push the wind out of the way. I have de-smogged my 90, four barrel, mild cam, ignition upgrade, I am getting (avg) 13mpg over the last four tanks of fuel (I like the 4bbl sound however), and I'm not on roads over 65mph speed limit.
I would be interested in seeing what the mpg difference is between the Wagons with the 3:31gears and the 2:73.
When looking into the overdrive option myself the experienced users seem to agree "using O/D to reduce wear on the drive train=good idea, expecting great gains with O/D in mpg=bad idea". If running 4:56 gears, well yea
I am willing to bet they fare the same. Sometimes the numerically lower geared rigs yield poorer economy than expected because they engine is working really hard to get it moving.

If mileage is the goal the Cummins 4BT or 6BT would be the answer. (Not to mention the grunt)

These AMC engines were designed when fuel costs were not even a significant concern in someone's day to day life.
__________________
Wag Rebuilt 360, 260H, 727, Locked 44, AMC 20, 208, 31" M/T's, 4" Rustys, 2.5" Duals. SOON:SOA SF, 496, T400, Doubler, D60's, 37" M/T's <-TOY
Cherokee Rebuilt 360, 2" Duals, mostly stock. SOON: Hot Street 401, 4'' Rustys, 33" BFG A/T's maybe a T-case to get rid of Q-Track <-TOW RIG
revelc is offline   Reply With Quote
Unread 05-05-2013, 07:28 AM   #5
KC87Wagoneer
Registered User
1987 FSJ Wagoneer 
 
Join Date: Jul 2012
Location: kansas city, MO
Posts: 52
Thanks for the info. I know I will never get great mpg. I would just like to be around 13-15. I am looking at the edelbrock performer intake, matching 500 CMF carb, headman headers with 2.5" exhaust, flow master muffler and cat, and electric fan. Right now the ignition upgrades include everything but the Multi spark box. That is next.

Did you notice a bump up in mpg after scrapping all smog?

I love driving the wagoneer, not going to sell no matter what the mpg. I had a 2000 Cherokee that got 17 and the difference in driving a full size is worth any additional cost. There is something very cool about being one of the only people out on the road with a classic the this.

So just to be clear, aod cannot be added to the 727 with a kit or mod?

Last edited by KC87Wagoneer; 05-05-2013 at 08:02 AM..
KC87Wagoneer is offline   Reply With Quote
Unread 05-05-2013, 08:05 AM   #6
RockRollin
"Positive.....I think"
 
RockRollin's Avatar
1990 FSJ Wagoneer 
 
Join Date: Apr 2012
Location: Grand Haven Mi, USA
Posts: 1,083
My air pump was gone when I bought it. The problematic issue of TOO many components with stock emissions system, (if it doesn't all work precisely, none of it works precisely)
I did the TFI coil, cam, t-chain, valve springs first, without much improvement (still stock 2150 carb) on economy. However power was much better, and ran/started much better. The biggest difference was the Edelbrock 2131 intake, Holley 1850 carb, streetfire controller, cleaning up vacuum system. That bumped me up from 8-10mpg to 13avg.
I'm not aware of any O/D options for the 727 other than the $3000 option. I did have a 92:1? gear in a 904 on my Diplomat, but that was a built race tranny behind a 450hp 410ci stroker Mopar. It didn't do much cruising.
__________________
"I like fun" Edd
Clawed: 90GW, TFI, Streetfire, 3"lift all spring, 31"BFG ATs, working RKE, Edel2131, Holly 1850, mild cam,
05 Renegade OME 927, 947, top plate, JBA 4.5s
RockRollin is offline   Reply With Quote
Unread 05-05-2013, 08:22 AM   #7
revelc
Registered User
1985 FSJ Wagoneer 
 
Join Date: Nov 2011
Location: Tyler, Texas
Posts: 663
Electric fan is a good upgrade but make sure your alternator is up to the task. I think the little cam will help. Unfortunately there is not an OD upgrade that won't cost $$$. The savings won't outweigh the gains. The performer, throttle body injection, cam, and exhaust should give you what you want. That is unless your like me and don't want computers on your rig

I noticed you haven't said anything about the cam. Are you worried about cracking the engine open? It is really straight forward and simple. You can save some steps and do it when you put the Performer on. The intake needs to come off to replace the lifters anyways. Just pull all the accessories off, remove the timing cover, check your timing chain (mine was loose), gently remove the cam, lube the new one up, slide it in and put it all back together. I did it with the engine in the Jeep in an afternoon. Just pull the radiator and grill.
__________________
Wag Rebuilt 360, 260H, 727, Locked 44, AMC 20, 208, 31" M/T's, 4" Rustys, 2.5" Duals. SOON:SOA SF, 496, T400, Doubler, D60's, 37" M/T's <-TOY
Cherokee Rebuilt 360, 2" Duals, mostly stock. SOON: Hot Street 401, 4'' Rustys, 33" BFG A/T's maybe a T-case to get rid of Q-Track <-TOW RIG
revelc is offline   Reply With Quote
Unread 05-05-2013, 04:24 PM   #8
KC87Wagoneer
Registered User
1987 FSJ Wagoneer 
 
Join Date: Jul 2012
Location: kansas city, MO
Posts: 52
I'm not scared to open it up. Already did that when I bought it. Overhauled the motor but just went stock with everything. I also had to open it back up to replace the timing chain cover. Did you use the edelbrock cam? Performer or performer plus? I've been looking at TBI but not sure what to pull it off of at the junk yard. Don't want to buy new, too pricy. Would love a matched accel TBI but it is $2,100.

By cleaning up vacuum do you mean scraping everything but heater and 4 wheel drive or do you mean new hoses and components?
KC87Wagoneer is offline   Reply With Quote
Unread 05-05-2013, 04:24 PM   #9
KC87Wagoneer
Registered User
1987 FSJ Wagoneer 
 
Join Date: Jul 2012
Location: kansas city, MO
Posts: 52
I'm not scared to open it up. Already did that when I bought it. Overhauled the motor but just went stock with everything. I also had to open it back up to replace the timing chain cover. Did you use the edelbrock cam? Performer or performer plus? I've been looking at TBI but not sure what to pull it off of at the junk yard. Don't want to buy new, too pricy. Would love a matched accel TBI but it is $2,100.

By cleaning up vacuum do you mean scraping everything but heater and 4 wheel drive or do you mean new hoses and components?
KC87Wagoneer is offline   Reply With Quote
Unread 05-05-2013, 05:44 PM   #10
revelc
Registered User
1985 FSJ Wagoneer 
 
Join Date: Nov 2011
Location: Tyler, Texas
Posts: 663
Quote:
Originally Posted by KC87Wagoneer
I'm not scared to open it up. Already did that when I bought it. Overhauled the motor but just went stock with everything. I also had to open it back up to replace the timing chain cover. Did you use the edelbrock cam? Performer or performer plus? I've been looking at TBI but not sure what to pull it off of at the junk yard. Don't want to buy new, too pricy. Would love a matched accel TBI but it is $2,100.

By cleaning up vacuum do you mean scraping everything but heater and 4 wheel drive or do you mean new hoses and components?
I used a COMP 260H cam. It has great vacuum, grunt, and you can use it with stock valve springs.

Hop on over to IFSJA and search TBI. I have not personally done it so I don't want to steer you wrong. I would assume any vehicle with a 5.7 would work well but I could be wrong.

Cleaning up vacuum lines would mean leaving only heater, air conditioning, 4X4, brakes, and vapor canister. Removing the smog pump, EGR, and whatever else in the myriad of rubber lines you seem unnecessary can be beneficial to a happy engine.
__________________
Wag Rebuilt 360, 260H, 727, Locked 44, AMC 20, 208, 31" M/T's, 4" Rustys, 2.5" Duals. SOON:SOA SF, 496, T400, Doubler, D60's, 37" M/T's <-TOY
Cherokee Rebuilt 360, 2" Duals, mostly stock. SOON: Hot Street 401, 4'' Rustys, 33" BFG A/T's maybe a T-case to get rid of Q-Track <-TOW RIG
revelc is offline   Reply With Quote
Unread 05-05-2013, 08:35 PM   #11
RockRollin
"Positive.....I think"
 
RockRollin's Avatar
1990 FSJ Wagoneer 
 
Join Date: Apr 2012
Location: Grand Haven Mi, USA
Posts: 1,083
I actually have the complete GM TBI setup in my shed, decided against it and went with carb. Again its not going to net much gain. Check the mpg realized by those that have done it.
As revelc siad, a vacuum cleanup is only running necessary vacuum, dizzy adv, brake booster, t-case controls, heater. I do use a gas tank vent canister, but there is no leeching from the intake vacuum
__________________
"I like fun" Edd
Clawed: 90GW, TFI, Streetfire, 3"lift all spring, 31"BFG ATs, working RKE, Edel2131, Holly 1850, mild cam,
05 Renegade OME 927, 947, top plate, JBA 4.5s
RockRollin is offline   Reply With Quote
Unread 05-06-2013, 12:13 PM   #12
muddy93
Registered User
1987 FSJ Wagoneer 
 
Join Date: Aug 2007
Location: Templeton, Indiana
Posts: 1,908
QUOTE"....I have upgraded the ignition, rebuilt the carb and put in a K&N air filter and have increased MPG from 7.8 to 9.4. I want to get it up to the factory 12 or better. Next is all new vacuum components, new EGR, headers, muffler, cat and intake before I do anything more expensive like lockout hubs. "QUOTE

Not sure why your MPG is so bad??? I have an 87 as well, with a totally stock drivetrain, encluding the exhaust, and all I have done to it is de-smog the engine, rebuild the carb, and spent a day tuning, and I'm averaging 13 MPG (that's about a 50/50 mix of highway and city). And that's with the old plugs, wires, cap, and rotor that were on it when I bought it (new ones will be going on soon).

With the tune up, warmer temps (choke staying on less), and the new tires that will be going on soon, I'm hoping I can squeeze a little more MPG out of it.
__________________
maroon 1987 Grand Wagoneer. stock for now...
muddy93 is offline   Reply With Quote




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.