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Judson Manning
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Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406
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With oil hovering at $100/bbl and my SUV (speciffically chosen to tow a JH to the race track) averaging 15-20mpg; I was a bit curious to see what kind of fuel milage my JH was getting.  You'd think a little car built during the crux of a world-wide oil crisis might just be a bit more efficient than a big honking SUV....

I never was able to source the part to adapt my Toyota W58 to the JH speedometer (let alone calibrate it!), so this little project of MPG has been difficult to start.  Fate would have me getting lost in the back roads of GA, AL and FL one too many times, and I chose to treat myself to a GPS system (thanks to John Cronin for the inspiration). 

The Garmin GPS just so happens to have an instantaneous speed readout and a trip odometer.  Yes, I basically spent $500 so I could get some idea of how fast I was going!

Anyway, on a business trip yesterday to Greenville, SC and back I had the chance to do some measurements and got a consistant 24mpg rating.  My sampling was basically 2 legs ~115 miles long up and back on I-85 at "highway" speeds.

Anyone else have some samplings of milage results?  Highway?  around town?  Think the IRS will let me start using the JH for business trips???

For those of you wanting some comparisons my car's particulars:

2.2 907/910 hybrid ~11:1 c/r DHLA 45s w/ 138mains & 57idle jets, essentially 104 cams EX&IN, W58 trans w/ .78:1 overdrive, 205/60R13 tires, top down, O2 reading ~13:1

I figure running with the hard-top will get 1-2mpg; switching to 107 cam on EX and trimming the carbs to achieve O2 reading of ~14:1 are worth another 2-3mpg as well.  Other suggestions???

Judson

Paul Koehler
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Joined: 04-06-2005
Location: Malone, New York USA
Posts: 88
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Glendale,AZ to Malone, NY - about 3000 miles, fully loaded in boot & behind seats, 2 people, with hardtop, at "highway speeds" ,  standard engine and carburation, 27mpg.

Judson Manning
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Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406
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I finally got the chance to find my old Road&Track, et. al. reports....

It seems the JH scored anywere from 18mpg("hard driving") to 21, 25, and even reports of as high as 27+mpg.  One can guess the higher numbers are probably 55mph highway results.  Of course the GT was scoring in the 18-19 range.

 

Judson Manning
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Joined: 03-14-2005
Location: Atlanta, Georgia USA
Posts: 406
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One more data point to offer this time with the hard-top installed...

121 mile leg highway cruising as before but now:  27.7mpg!!!

Not bad considering $4.19/gal for gas and my 25 year more advanced Mercedes C230 kompressor was getting about the same results.

Jensenman
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Joined: 04-14-2005
Location: Columbia, South Carolina USA
Posts: 156
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If you are having problems adapting the J-H speedo to the W58, here's what I did: I installed a 31 tooth speedo gear. Problem is, it's too small to engage with the drive gear on the output shaft. So, I got a piece of aluminum bar stock, turned it to the same OD as the Toyota speedo housing. I then bored a .750 hole offset .100 from center and cut an O ring groove around the outside.

I then turned the Toyota speedo gear housing to .750 od and then tapped it into the piece I made, using Loctite Red to seal the two together. I now have an eccentric housing which can be turned to adjust for different speedometer drive gears.

The cable is from a 1986 Mazda RX7, it is long enough that the 90 degree drive adapter is not required. It is necessary to drill a 1" hole throught he 5 speed crossmember to route the cable, and to remove the J-H quick disconnect end and install it on the Mazda cable.

With 195/60/14 tires and a 3:45-1 rear axle, the 31 tooth gear is approximately 10% slow at 60 MPH. It really needs a 30 tooth gear, but Toyota does not seem to offer that. This gear is very similar to other Japanese makes, I'm going to keep checking around until I find a 30 tooth gear.

 

 



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