That's a heck of a project to take on over a weekend unless you are 100% certain about everything you will need to do and the parts you will need.
When I converted my pickup, I ended up waiting several days just to get a simple sleave bearing. Another unexpected (though really easy) mod that I had to do was pound out the floorboard under the clutch pedal to make room for it's travel.
After driving about 100 miles with the 5 speed it became evident that the RPMs were running way too high on the highway. From the factory the manual trans cars were equipped with a 3.31 ratio differential vs 3.73 diff behind the automatic transmission. Both manuals and automatics run about the same RPMs in top gear. A taller 4th gear on the automatic makes up the difference. I on the other hand was left with a 3.73 manual trans. The chart below shows the RPM vs speed for the 5 speed manual with both differentials. Gear ratios go from first to fifth from left to right. In 5th gear theres a 9 mph difference at 3000 rpm. Doesn't sound like much but the noise gets to me and it can't be good for fuel economy. Check out the numerical difference between 1st and 2nd gear. Volvo picked gear ratios at random.
Here come the 3.31 axle. My beater neon is on the right.
After 1000 miles on the conversion and 4 fill ups, everything seems to be working just fine. Haven't had any unpleasant surprises... yet. Fuel economy improved from my usual 20-22 mpg to 24, 25, 26, and 28mpg for each respective fill up after the swap. As an experiment, I blocked off the EGR pipe at the intake to see what would happen. So far so good. Got 28mpg on the 4th fill up with EGR blocked off. Idle is a little smoother. I guess my EGR valve was leaking. Best of all, the EGR block off only cost me 5 cents.
Now its time to move on to some aerodynamic improvements... on a Volvo LOL
The EGR valve is mounted on top of the oil/air separator on the side of the block, underneath the intake. The pipe from the EGR attaches to the intake between cyl 2 and 3 where all the vacuum ports are. I suspect only California cars got it in 89. Later LH 2.4 and 3.1 cars didn't have EGR. The EPA has a listing for 89 240s with and without the EGR valve. http://www.fueleconomy.gov/feg/compx...Field=Findacar
Wow. I did a Volvo 145S many years ago from the Borg Warner BW35 to a Volvo M40 four speed, brings back memories.
The best was my Volvo 122S wagon with the stock 4.7(something) rear end Vs the 4.11. On a stock car, this would be bad, but, the car has the drivetrain from a 1800S, so I had a modified B20 and an M41 (overdrive) which gave me a few more gears and a taller final drive, and a Volvo Amazon that could go 120 MPH and bark the tires on 1-2 shift!