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Volvo Adventures is an independent New Zealand based resource for the older Volvo models

122-B21-M41 Project
by Club member Paul Malloy, USA

This is my '65 122 which I installed a B21engine, B23 Sidedraft Carb and an M41 O/D Gearbox (in the process of installing it right now) . No alterations were done to the body of the car so far. 

The major alterations were done to the engine. Which included fabricating custom motor mounts, alternator bracket, radiator (electric fan). The intake manifold was modified.

I started this project when someone gave me a fresh B21/M46 + everything attached to it. So, I thought it would be worth trying in my 122. I did trade the M46 for a rebuilt M41 to limit the alterations to the car's body. 

Sorry the pictures are a little blurry. It was a gloomy, snowy day when I took the pictures, but as soon as I have an opportunity I will take new and better photos. 

I think this conversion was fairly straightforward. Most of the time was spent waiting for work from the fabricators. 

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The following is a quick list of the major work done: 

  • Motor mounts-> the original engine-to-motor mount brackets were cut, altered, and welded back together. 
  • Oil Pan-> a '75 B20 oil pan and oil pump was used to compensate moving the engine from the slant to the vertical position. 
  • Carb set-up-> a Canadian 1983 B23 SU with a '79 intake with all accessories was used. I thought the carb set-up would get the car on the road faster until I can get the K fuel injection back on the B21.
  • Intake manifold-> a pie section of the carb intake manifold was removed and the manifold was welded back together. I think this was the most difficult alteration. If I went with a K fuel injection system, the original B21 fuel distributor and a B21 Turbo intake manifold set-up could be used without altering the manifold.
  • Gas pedal-> the Canadian carburettor 240 gas pedal setup with a cable will be used. 
  • Exhaust -> the B21 downpipe was cut and welded into the 122 exhaust system. 
  • Radiator - A custom radiator was made using the 240 radiator tanks with a new core. The 122 radiator was used for the mounting brackets.

The project has been ongoing since 1999, with the engine installed in July '99. The engine is running well in the car right now, but the newly rebuilt M41 tranny needs to be installed along with some miscellaneous stuff (mostly the gas pedal set up) to get it on the road. 

Updates July 2006:

Here's a couple of pictures of my 122 with a B21/M41 with electronic fuel injection(EFI).

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The first picture shows the modification of a B230F intake manifold. The throttle body needed to be moved about 90 degrees to fit in the engine compartment.

The second and third pictures shows the engine compartment with the EFI using a system called Megasquirt.

The fourth picture shows the 240 fuel pump setup mounted under the driver's side back seat.

The fifth picture shows the surge tank mounted in front of the gas tank. A small fuel pump is used to feed the surge tank and main pump. The gas tank was modified with a return line.

The car has been running with the carb setup from 2003, but I had a problem with the fuel pump vaporing locking. The problem was solved when I modified the gas tank with a return line. The car ran great with the carb setup.

The car was modified for EFI starting in May 2005, but didn't get it finished until January 2006. I used a system called Megasquirt to run the EFI. It is a build-it-yourself system that is fully programmable and supported by the users. The cost of the EFI main unit is around $150US. You solder the unit together, use pretty much any EFI components (fuel injectors, sensors, fuel rail, etc) that you want. A very flexible system. I ended up spending around $1000US (mostly to modify the B230F intake manifold and gas tank) to get the whole EFI running. The car runs much better than the carb setup with a better response and more power. 

I'm planning on having the Megasquirt unit also run the electronic ignition system in the next couple of months.

I upgraded the brake master cylinder to a dual master in April 2006. Just the front brakes on one circuit, and the rear on the other circuit setup. 

I've taken the car off the road to rebuild the front end, and install a collapsible column steering box from a '73 1800. Hopefully, install a true split dual circuit brake system from a '73 1800. I have a rear disc brake rearend from a '73 1800, but planning on using the '65 rear-end with the drum brakes until I can get some torque arms and support arms fabricated to install the '73 1800 rear-end to the '65 122 body.

Paul Malloy

USA 1999 - 2021