Guess the MPG Worn vs. Rebuilt (+)

vintagetrk

Precision Fit
All-Star
Apr 28, 2018
637
NW Wyoming
First Name
nathan
Willys Model
Pickup
Willys Year:
1958
I was going to put this in my build thread but I thought it might be fun to do a friendly game of guess the milage on a new rebuild +. This won't be very scientific but it will be fun. Once I get my transfer case back ( been gone since August) I can assemble and test. The idea is to base the test on add on and improvements, on top of the refreshed engine. EDIT *****All for a chance at a 3 finger fixed blade every day carry knife hand made by me. Includes leather sheath. I will draw the name from the folks closest to the correct answer. All answers welcome! I'll build the knife and post the picture.

1958 Willys Truck before my rebuild: 12 mpg Tested @ 3,000 ft altitude 35-40 mph on a 40-mile trip.
  1. Original 226 ( worn out, standard bore)
  2. 7.3 compression head
  3. Weber 34/36
  4. Square stock cloth air filter a.k.a garbage.
  5. Pertronix ignition ( smoothed out the engine a little but never felt any HP gains)
  6. 4:88 gears with 31" radials on 15 " rims

Rebuild: I'll try to do a 35 mph - 45 mph, 40-mile test on a two-lane relatively flat through farm country as close to Nebraska as I can get. The test will be at approx 4,500 - 5,000 ft. altitude. I will start at the gas station and come back to the same station, add fuel and do the math.

I hope to have this done in the next couple of months. Not apples to apples but it will all play into the discussion and results. No doubt that there is an average performance on all the trucks built-in 1958 regardless of where they were sold.

Spec.
  • L6-226 with a 0.040 bore if my math is right it is a 231.7 ci. now. Correct me if I have made an error.
  • 7.3 compression head ( shaved slightly to flat) The block deck was shaved slightly as well. Intentions were to flatten not performance.
  • Weber 34/36 re-jetted to compensate for high altitude 5,000 ft +. I didn't add a lot more fuel just tried to get more air. The primary jets in my Weber were a little lean for the 226 to start, based on Weber's tuning guide.
  • Larger 8" round aftermarket air filter & adapter.
  • Pertronix ignition.
  • 4:88 gears, 31" rubber, 15" rims (because they are in good shape and I want to sleep inside. Wife hit tilt on my jeep spend over the last year (s) Ha!)
  • 30% overdrive. I read that this might be too much OD based on the small displacement and HP of my engine, on paper. I felt that any improvement over no OD was a win, win and I wanted to see if paper translates to real life. An expensive gamble but we learn something so there is something to gain even if results are not optimizing the rpm as best as possible. I will use the overdrive on the test but try to keep my speeds the same.
  • Rebuilt transfer case with tapered roller bearings ( when I finally get it back) & Transmission Not sure this will have any effect on MPG. It was done for durability reasons.
  • New SS exhaust with Smithy 22" glass pack. The length of the new exhaust is the same configuration give or take a couple of inches. Again, I'm not sure this will do much on a low RPM engine but I am sure it will sound good.
Other changes that probably won't matter.
  • 11" self-adjusting brakes with dual master no booster added. Not sure weight is enough of a difference up or down to matter but it's listed anyways.
  • Plastic replacement tank. * I am thinking about adding the original tank next to the plastic tank just to have an auxiliary tank but that might be down the road. I'll update that if it does happen.
  • Octane- I used to be able to get 87 octane with no ethanol in Nebraska. In Wyoming, I might have to shop around or use 91 octane. As long as I stay out of the ethanol I should be fine. The compression is so low I'm not sure how much octane will play into the equation?
I am sure there are some guys out there with vastly more knowledge than this weekend wrencher. I'd like to hear your thoughts!

My guess is 18 mpg. I base this off of the Weber tuning, overdrive, and the refreshed engine working more efficiently.
 
Last edited:

ndnile

Precision Fit
Oct 23, 2017
591
Northern CA
First Name
Doug
Willys Model
Wagon
Willys Year:
1959
My guess is 16 MPG. It is Nathan's post, so it is up to him. Instead of everyone throwing out numbers with many of them being the same, how does it sound that if your guess has already been posted that instead of adding another post, you "like" the existing post. Sort of like the calendar voting.
 

vintagetrk

Precision Fit
All-Star
Apr 28, 2018
637
NW Wyoming
First Name
nathan
Willys Model
Pickup
Willys Year:
1958
My guess is 16 MPG. It is Nathan's post, so it is up to him. Instead of everyone throwing out numbers with many of them being the same, how does it sound that if your guess has already been posted that instead of adding another post, you "like" the existing post. Sort of like the calendar voting.
Sounds like a plan!

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vintagetrk

Precision Fit
All-Star
Apr 28, 2018
637
NW Wyoming
First Name
nathan
Willys Model
Pickup
Willys Year:
1958
okay, I'm going to make this game a little more fun. I make custom knives for a living. I'll give the closest guess group a chance at a 3 finger EDC knife. It's a little knife with a 2 to 2.5" blade and a handle that fits across a few fingers. Small enough to fit in the front pocket no problem. I'll do a hand made sheath as well. I'll draw a name out of a hat of the group that came the closest.
 

vintagetrk

Precision Fit
All-Star
Apr 28, 2018
637
NW Wyoming
First Name
nathan
Willys Model
Pickup
Willys Year:
1958
I would think the overdrive would help some???
The only issue would be the 30% OD on grade would not hold any kind of speed. I'd be shifting out of it all the time. It's only 5% better than the standard OD . So it's not going to be catastrophic by any means. I actually think the 6 cyl will do okay with it.

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PTV

Sharpest Tool
Jan 3, 2020
316
SW Pa.
First Name
John
Willys Model
Pickup
Willys Year:
1958
Yeah that would knock the ratio down to a 3.22 ratio in high. Would 2nd overdrive be "higher" than straight 3rd without overdrive?
 

scramboleer

Super Moderator
Staff member
All-Star
Aug 16, 2011
6,908
San Francisco, California
First Name
Dan
Willys Model
Wagon
Willys Year:
1964
Yeah that would knock the ratio down to a 3.22 ratio in high. Would 2nd overdrive be "higher" than straight 3rd without overdrive?
On my dad’s 1946(ish) CJ2A with the Saturn overdrive, the answer is “no.” The overdrive is more like a gear splitter. I tell the kids we are shifting into “second-and-a-half.”
 
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