Volvo RWD 120-130 Forum

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fuel economy question 120-130

122s tend to get fairly good fuel economy on the highway, but poor fuel economy in-town. i know this is true of most cars, but also wondering if there's a way (adjustments, that sort of thing) that can improve fuel economy in-town on a b18. on a related note, does converting a b18 to fuel injection result in any measurable improvement in fuel economy?

thanks again,
floyd








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fuel economy question 120-130

Check the mixture of the SU's...I've had the same experience with fuel economy (good highway, bad in city) and my car was very rich. The SU's will lean out at cruise, but can be pig rich around town as the vacuum signal is not constant or consistant. I'm working on a wideband O2 sensor to varify if my assumptions are correct, but I think they are - I don't know if I can tune that characteristic out of the carbs, but this winter I'm going to try.

Craig








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fuel economy question 120-130

Let us know the results when you get your O2 sensor/gauge installed.

There has to be an SU needle that's ideal, there's only, what, around 160 different ones to choose from...

I'd like to hear your opinions of your 3:73 axle swap too; I want to have the ratio changed in my wagon too, and it will either be 4:10 or 3:73.

I'm thinking 3:73 might be ok with 50 series tires; but I don't want the car to be too doggy in the acceleration department.
I prefer not to mess with overdrive; just one more thing to go wrong, from my unhappy experiences.

Bill








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fuel economy question 120-130

I'll let everyone know the results of the O2 meter when I get it done :-)








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fuel economy question 120-130

Hi Craig: I've thinking about a wideband O2 sensor as well and can't decide the best place to put it. Where are you going to mount your sensor? And what meter are you going to use?

Cheers,
--
Barry -- 1967 122S 'Betty'








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fuel economy question 120-130

If the car is in an excellent state of tune already the biggest improvement you could probably make would be to adapt your driving style; gentle acceleration, adjusting your speed to avoid getting caught by redlights, try to keep the car rolling and avoiding braking and doing as much coasting out of gear as possible.
This also saves wear and tear on the car.

Allowing generous distances between your car and the one ahead of you gives you a buffer and can let you avoid some of the stop and go of traffic.

Keep the tires fully inflated, and using 165's will give less rolling resistance than a wider tire.

The area I live in is moderately hilly, and I always like to make the hills 'pay me back' by using them on the way down to keep the car rolling out of gear.

SU's give good fuel economy if they're in good tune and properly adjusted. CD ignition (MSD6) can let you run a leaner mixture, among other benefits.

Clean all the junk you don't need out of your trunk.

Lose weight, if applicable ;)

Bill








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fuel economy question 120-130

The biggest detriment to in-town fuel economy is generally the driver's lead foot, unless the carbs, and especially their throttle shafts are worn.

And on the related note, again depending on your lead foot, probably not enough
to make it worthwhile, especially considering you gotta find space for a lot of stuff!
--
George Downs, Bartlesville, Heart of the USA!








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fuel economy question 120-130

thanks for the suggestions - don't know how much more weight i can lose, but maybe i'll take a couple of extraneous doors off.

cheers,
f.








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fuel economy question 120-130

I didn't quite go that far, and it wasn't a Volvo, but I did attack an old FWD Morris years ago. I took out EVERYTHING that I didn't really need: back seats, insulation, even door latches and window winders on the back doors, took an air chisel to everything else. I replaced the door trim panels with light (1/8) ply; they looked fine with a coat or two of polyurethane. Held the rear doors/trunk lid on with a row of sheetmetal screws, on and on.

All this (and more) saved nearly 25% of weight (I weighed it all as I took it out), and the results were quite spectacular: much, much faster car, and fuel mileage went up by almost 40%. I don't recommend going that far, but it is amazing what can be done with less effort.

And certainly higher tire pressure makes a big difference, as does removing extraneous attachments (roof racks and the like, and making sure engine tune is perfect...







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