Various users of older cars have reported one or more of the below.
Smoother idle.
A feeling of better torque.
quieter engine.
better milage.
Does mine idle smoother? Maybe a little bit when it's up to working temperature, but it's marginal at best.
Better torque? No definetely not, if anything it's a little bit more sluggish.
Quieter engine? Yes oddly enough, it is a little bit more silent.
Better milage? well that remains to be seen.
The verdict is in and, yes, to my surprise it made quite a difference on the milage.
First let me explain how we measure that over here.
Unlike Americans who measure distance per fuel unit, (miles per gallon) we do the opposite and measure fuel per distance (liter per mil) A Swedish- sometimes called Scandinavian- mil is 10 km.
An old style car would usually take one liter per mil, that’s what my Volvo Amazons took and my Volvo 740s and my SAAB 900 and so on, you get the picture.
My current 30 years old Volvo 940 was taking a whooping 1,14 l/m when I bought it, it got a bit higher after a while, around 1,17 it even went as high as 1,19 at one point, so I decided to try and get that down.
I first did all the things you normally do anyway, changed the oil and oil filter, spark plugs, wires, distributor cap, rotor, checked the tire pressure, changed transmission fluid, and since I changed the cam shaft belt I also changed the water pump and fluid.
I was now back to 1,14
I also swapped the engine fan for an electric fan after a tip on a Utube video, where a guy removed his fan on an old 240 and saved a deciliter per mil. Didn’t do anything on mine.
Next step was to change the old fuel filter for a new one, during the process, as I was jerking the old filter around to get it out, the fuel pipe sprung a leak, turned out it was pretty rusty, fixed that with a piece of hose.
And that actually made a rather big difference, I was now down to 1,09, and since winter was coming and I work on my car outside, I stopped fiddling with it.
Come mars and I stumble on a Utube video about some magic spark plugs that supposedly will do wonders for old cars in terms of fuel consumption, among other things.
I do a little googling around and it seems that a lot of people speak highly of these spark plugs, called E3, when used on older cars, with newer cars not so much, it seems like all the computer shit in newer cars can’t handle these plugs.
So I ordered four plugs, they cost about seven bucks a plug, so no overprice really.
They arrive and I install them, and now the verdict is in, they did to my big surprise do quite a difference, I am now down to 1,04 liter/mil.
From 1,09 to 1,04 on spark plugs alone is quite remarkable, I will stick to these.
Next is to change the air flow thingy and change the spark plug wires for some new NGK wires I have had lying around since autumn.
https://en.wikipedia.org/wiki/Scandinavian_mile
Edit: for you Americans, that's 0.013208603 Gallons per 6.2137119 miles saved.
Or, in other words, about 2,4 ish litres, or 0.6 ish gallons per full tank.