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Gas mileage for a flathead Willys Jeep; MPG's for Willys Jeeps
Topic Started: Dec 15 2012, 08:46 PM (2,069 Views)
mikec4193
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Hi Everyone

I am about waist deep in a 1947 Willys CJ2A rebuild and it is going to be totally stock when finished. I really want to run this vehicle to my day job (daily if possible)which is about 11 miles from my house. I think I have stock gears in the rear end also.
What kind of MPG's should I be looking at when it is all said and done?...Motor is totally rebuilt and the transmission will be too when reinstalled in the next couple of weeks.
Any insight would be wonderful.

Thanks everyone.

MikeC
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Bob
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Bob
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A good guess is anywhere from 15-18. The low gears and low power of the motor contribute to this.
Bob
1953 CJ3B
1965(?) CJ5
1949 Jeepster
1947 Cj2A
2004 Kubota l3400
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oldtime
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Mike, Welcome to the CJ-3B Bulletin Board !
Quote:
 
I really want to run this vehicle to my day job (daily if possible)which is about 11 miles from my house.
Seems perfecrtly reasonable to me if enroute posted speeds do not exceed 55 mph.
Quote:
 
I think I have stock gears in the rear end also.
1947 should have a Dana model 41.
This particular axle was only manufactured with 5.38 final drive ratio.
No aftermarket gears are available for the D41.
Quote:
 
What kind of MPG's should I be looking at when it is all said and done?...
Realistic sustained top speed without O.D. is about 50 mph.
Driving 45 mph will yeild better mpg due in large part to jeep not engineered for aeroynamics.
Expect slightly less mpg than the F134 equivilant.
With 10% ethanol fuel figure about 16 MPG.

Personally I gave up on the Go-Devil engines after the national speed limit increased above 55 mph.
That was back in the early 1980's.
The Hurricane only provides 12 more HP but that's a large percentage compared to the Go-Devil's 60 HP.
The Hurricane provides just enough power that I can maintain 60 mph on the steepest Missoiri Interstate grades at wide open throttle (W.O.T.)

My current one and only daily driver, a 1962 CJ-3B is set up with 5.38 final drive, 29.5" tall tires and Warn O.D.
Currently building my final F-134 powered 3B .
Rock Crawler using factory parts from the Willys Motors era (1953-1963)

http://s4.zetaboards.com/CJ3B_Bulletin_Board/topic/30228766/1/#new
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johnrb
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You notice Ken (oldtime) mentioned overdrive.
That's the easiest upgrade you can do to an old CJ. Simple bolt-on.

It'll give you a little better gas mileage and it'll give you a little more top speed. Nothing major on either front. But the real advantage is that it lowers your engine RPM 25%. Those engines were red-lined at 4,000 RPM but you probably don't want to push those 65 year old connecting rods that hard. I feel most comfortable keeping my 3B's F-head at 3,000 RPM or below. The F-head's torque curve peaks at 2,200 RPM so that's a good target. Overdrive is great for that. And it turns your 3-speed into a 6-speed. I love more gears.

Used Warn / Saturn overdrives can be found but it's a crap shoot as to their condition. You can get a nice, shiny, new one from Herm
http://hermtheoverdriveguy.com
but it's not cheap - $1,000

I think it's worth every penny and Herm's "tech support" is priceless.

If you do find a use one for cheap, you may end up having Herm rebuild it before it'll work. Might as well save the hassle and get a new one.

Or you might find a "whole" CJ with overdrive in it. I bought a totally rotted out 3B for $900 that had a good, running engine, sound drive train and a working overdrive. It was a bargain. I got my money's worth on that one.
John Burch - west burbs of Chicago
1946 2A - now I have one older than me
1949 - me - no longer older than all my vehicles
1954 3B - mostly stock - fun driver and snow plowing
1957 - 6 cyl Station Wagon - hope for the future

past Willys
1954 3B - no tub | 1959 3B - engine in pieces in a box

past addiction - VW
1969 Bus | 1970 Westfalia Camper | 1984 Westfalia Camper
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Other Willys Jeep forums:

The CJ-2A Page has a CJ-2A Message Board.
There is also a CJ-3A Page Forum.
For CJ-5 and Dauntless V6 postings, see the Early CJ-5 Bulletin Board.
The Old Willys Forum is dedicated to wagons and pickups.
Surrey Gala and Dispatcher Jeeps are under DJ-3A Dispatcher Posts.
The M38/M38A1/M606 Preservation Group has a forum.
For other CJ and military Jeeps, see the g503 Message Boards.
See the Forward Forum for Forward Control Jeeps.
To post ads for other Willys parts or Jeeps, see the WillysTech Buy/Sell/Swap Message Board.
For tech problems with other Willys models, try the WillysTech e-mail list.
The Bantam Trailer forum covers Jeep trailers.