Fuel economy


The place to put your L, R and S "Build Off" story.

Yard Art
Yard Art

Posts: 53

Joined: Sat Nov 04, 2017 4:31 pm

Post Thu Mar 01, 2018 9:30 am

Fuel economy

I've been driving my original L110 and having a blast, I've changed the rear end to a 1998 Dodge Dakota so I can now get up to 95 kilometers an hour but was wondering if there are any suggestions on improving the fuel economy. Running with the original carburetor.

Golden Jubilee
Golden Jubilee

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Joined: Fri Apr 08, 2016 4:52 pm

Post Thu Mar 01, 2018 10:48 am

Re: Fuel economy

Didn't mileage improve with the differential change?

Yard Art
Yard Art

Posts: 53

Joined: Sat Nov 04, 2017 4:31 pm

Post Thu Mar 01, 2018 3:10 pm

Re: Fuel economy

It did some what, was just wondering if a carburator change would help both power and economy

Golden Jubilee
Golden Jubilee

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Post Thu Mar 01, 2018 3:50 pm

Re: Fuel economy

You are driving an old lump that is not aerodynamic and the engine was developed around twenty five cents a gallon fuel. The lump seldom exceeded 40 mph. farmers were often the buyers of IHC pickups and farm marked farm fuel was ten cents less per gallon.
If you want economy or power buy a modern truck or plan on making changes to the power train. Members of this forum have installed the Oldsmobile quad four, the SBC and then there is my choice of Cummins.
Cummins offer a plug and play crate engine with the lsf series. These engines come in 2.8 and 3.8 litre.
I installed a V8 6.9 Diesel in an R120 and the fuel economy went from dismal to 20 plus mpg.
If you want your old Binder to go faster and do it safely, put it on a trailer and tow it in comfort in a Diesel Ram.
I would rather have tools I do not need than to need tools I do not have
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Golden Jubilee
Golden Jubilee

Posts: 2028

Joined: Fri Apr 08, 2016 4:52 pm

Post Thu Mar 01, 2018 4:42 pm

Re: Fuel economy

Here's what I think:
Fuel mix is directly related to engine temp. Within reason the warmer the engine runs the leaner you can run mixture. Modern engines have 192F thermostats and routinely run 200F+. These are pressurized cooling systems, though.
Put a hotter tstat in your IHC with a pressurized radiator.
Timing advance has to be active and quick. Vacuum advance has to work.
Old IHC engines are relatively low compression. You might try advancing distributor a tiny bit at a time. Pinging or spark knock shouldn't be a problem but ping and knock should be avoided. Everything "new" I work on is always on the ragged edge of spark knock/ lean mixture. That's where the best performance, fuel mileage and cleanest emissions are.
EGR (exhaust gas recirculation) is a bad word among performance enthusiasts but a EGR valve keeps engine from knocking and pinging, cools down overheated combustion chambers (where the dreaded emission NOX gas forms) and actually increases fuel mileage because it is filling the combustion chambers with spent exhaust, not fuel and air.
Finally, you can try making carb power valve open a little later and/or lean idle mix out a bit.
Also try a more free-flowing air filter system. Restricted air filter systems naturally cause more fuel consumption.

Golden Jubilee
Golden Jubilee

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Location: Lyman, IA

Post Thu Mar 01, 2018 10:04 pm

Re: Fuel economy

I will 2nd everything MM wrote, and add that the lower compression on these engines increases torque but not fuel mileage. If the compression is low it is possible to over advance without getting spark knock, with todays fuels. Don't go too far from timeing spec even if there is no knock.
Check advance curves with an Advance timing light, make sure both mechanical and vacuum are working correctly. As MM recommends, fit a 192 deg thermostat and make sure the heat riser flap can move and the thermostatic spring works.
Once all of this is done, then you can start on the carb, but that shouldn't be done lightly, it takes a lot of note taking and making small changes and documenting what happens so you can go back if you make it worse.

Golden Jubilee
Golden Jubilee

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Location: Canada's left Coast

Post Thu Mar 01, 2018 11:23 pm

Re: Fuel economy

CUT AND PASTE: the lower compression on these engines increases torque
Are you sure about that?
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Golden Jubilee
Golden Jubilee

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Location: New Salisbury, IN USA

Post Fri Mar 02, 2018 6:55 am

Re: Fuel economy

We know these aren't high-rpm engines...about 3600 is the top engine speed they were designed for.

The low compression moves the torque peak lower in the rpm range...I think that's what CB89 was referring to.

One previous forum member--can't remember who--put pistons from a tilt-valve engine in a straight-valve engine, and ended up with around 13:1 compression. His complaint wasn't detonation, it was overheating at that compression ratio.

On the C-series ag sixes, to raise compression above what available pistons would do, you put a truck head on 'em. Obviously, there isn't a similar option for the trucks.

Can you use the "Fire-Crater" ag style pistons in the truck engines? I don't know. It has to do with compression height, pin diameter, and whether the domes will clear the valves in the truck engines. But you can do some research on that.

Follow VWJAKE's posts on this forum...he's using throttle-body fuel injection on his engine. EFI might be the key to improving MPG, as the air/fuel ratio will likely be more stoichometrically correct throughout the driving range...if set up correctly.


Will any of that get you better MPG? I honestly don't have firsthand experience enough to tell you.
My posts contain my own opinions...your mileage may vary, void where prohibited, objects in the mirror may be closer than they appear, and alcohol may intensify any side effects.
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Golden Jubilee
Golden Jubilee

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Post Fri Mar 02, 2018 9:07 am

Re: Fuel economy

Bear in mind that these engines were developed when 15, 16, 17 mpg was normal and the cost of gas was below 20 cents per gallon. Relatively speaking that was still expensive for gas based on the cost of living at that time. (I can remember my dad, in 1958, grumbling about having to pay 19 cents a gallon) Factor in driving conditions were poorer then. Hiway speeds lower. These are essentially farm implements by standards of that era. Also factor in elapsed time, wear and tear, changes to gasoline and oil and it’s really a miracle if your truck still gets 15,16,17 mpg. You didn’t state what mileage you’re getting, so just remember this old technology isn’t up to modern standards. Judge it for what it is, not what you hope it to be. And yes, applying new technology can certainly make old things work better to a point. (Trying to throw a brick through the air will not get the same results as a football spiraling downfield)
L110 owner since 1974, finally rebuilt 2014.

Golden Jubilee
Golden Jubilee

Posts: 5160

Joined: Thu Nov 29, 2012 9:28 pm

Location: Lyman, IA

Post Fri Mar 02, 2018 9:56 am

Re: Fuel economy

Lower compression lowers and broaden the torque curve range, which is why ag and truck engines all have lower compression then their automotive counterparts. While high compression raises peak power it does so at the cost of useable torque band.
In the era of 9:1 compression on cars, truck still were at 7:1 or less. In diesels light duty engines were 21:1 where heavy duty could be as low as 13.7:1. with electronic on diesels and direct injection gas that has changed that in recent years, but at the time we are talking about it was the norm..
In trucks it is about torque more that HP.
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