My mistake.  The rears are 215/60/15.  Bought two new 215/70/15s today.  RPMs should drop approx. 6.5%.  The fronts will need to be replaced too when money allows.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Those rear tires are only about 25" diam.  which seems pretty short for the application.  I'd switch to 235/75's if possible.  The 3.00 gear is about as high as you'd want to go already, IMO.  I thought of another potential mileage "robber" :  the drive line or more specifically, the u-joints.  Check the pinion angle carefully with normal load and on a level surface.  A mis-aligned drive shaft can soak up power like a proverbial sponge.  Goggle the proceedures, specs, etc.

I would be open to that.  The 205/60/15s have never looked great in the wheel opening, I've just accepted them.  Same deal on the 195/60/15 fronts.  The rear is an 8 in. 3.00.

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Mike.  Have you considered a rear gear change?  For a short term test without a gear change, you could try some tires with a larger rolling diameter and see if that helps the fuel mileage.

Lorena, Texas (South of Waco)

Mark, the H20 pulley is a car type which is underdriven compared to the truck, but the rebop aluminum pump supposedly puts out about 20 percent more than stock.  Maybe a stock pump would be better.  There is a 14 in. electric and a 15 in. mechanical fan.  The mechanical is unshrouded and pretty far away from the rad. so I think of it as a "helper".  Oil is currently 10/30 VR-1, with synthetic lube in trans and rearend. 

On the CR I had to jump through hoops to get it that high with flattops.  113s milled .035 and block decked .028, head intake flange milled .046.

Last summer I revisited the advance curve, but dont remember exactly where it is now.  I was worried that too much cruise advance would be wasting a lot of energy, I think the vacuum advance was set at 11 max., centrifugal 10, and initial 10, for a total of 41.  But at 67 or so MPH the rpm is around 2800, and not all the centrfugal may be showing yet. 

Wow you have experience with a Jailbar!  Not that many people have seen one, much less have driven one.   

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Mike, what about slowing the water pump down with an underdrive pulley on the crank?  I know this would recquire a bit of clever machining but that would lessen the parsitic horse power drain while perhaps allowing the water temperature to rise a bit.  A few other random thoughts: Are you running a clutch type fan?  You might think about removing the fan all together and going electric only.  Lighter oil like 5W-30 would help too.  As long as you could maintain 40 psi + or - at cruise rpm it should be fine.  Synthetic lube in the trans and diff. are a good choice.  Multi-strike ignition, short centrifugal advance curve (all in by 3000 rpm), AND vacuum advance.  Front wheel alignment adjusted for near 0 toe in with radial tires.  9.2 : 1 compression ratio is plenty conservative even with iron heads IMO.  A little more wouldn't hurt.  BTW, I really like your '46.  I learned how to drive behind the wheel of a 3/4 ton '46 Ford- many moons ago.  It was a flathead V-8 w/ granny low gear 4-spd.  Good stuff, that.

A 195 thermostat might be a good idea.  Then maybe the thing would run at 180.  There is a quality Robertshaw 180 in place now. 

The low temp issue occurred with my earlier 292, same truck, with a 4 row big ass '46 radiator.  New engine, significantly higher static CR of 9.2:1, and a relatively small 2 row aluminum radiator with basically no change in cruising temps.

The O2 meter is something I have thought about long enough, that I MAY get one.   

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

Mike, 18 mpg sounds fairly good to me at first blush.  I am not familiar with your specific combination so it's hard to speculate.  That said, one variable besides the gasoline is the air.  The density altitude + relative humidity has a huge effect on power.  The E10 is probably costing you roughly 3% in mileage but bad air could be even worse.   I also noted that you are running the motor pretty cool re. water temp.  I might try bumping that up at least to 180 if not 195.  IMO, a lot of heat energy is going into the cooling system and not to the rear wheels.  Of course that's just a wild ass guess but I think your target of 20 mpg is not unreasonable with all things optimized.  A broad band O2 meter would go along way to document your fuel curve (I wish I had one! LOL).

I think Ted said by law Premium gas cant contain ETOH.  Maybe in Texas,  but here in OR premium does have ETOH.  There are only two stations in town which carry 100% gas, and it is in the premium grade.  Too bad they dont have 100% regular.  The cost is close to 4.50/ga.

The friend that went along for the trip didnt want to drive his nice '56 Chevy, because it gobbles fuel at the rate of 8 ga./mile.   .  Another friend didnt want to take his Packard due to it's 10 ga./mi.  

Mike, located in the Siskiyou mountains, Southern, OR 292 powered 1946 Ford 1/2 ton, '62 Mercury Meteor, '55 Country Squire (parting out), '64 Falcon, '54 Ford 600 tractor.

I read the other day that no premium fuels contan alchohol Period, so any premium gas has to be 100% gas.

55 Vicky & customline

58 Rack Dump, 55 F350 yard truck, 57 F100

59 & 61 P 400's, 58 F100 custom cab, 69 F100, 79 F150, 82 F600 ramp truck, 90 mustang conv 7 up, 94 Mustang, Should I continue?