The forty series torque converters are the go-to for eight to eighteen hp engines like the predator 420, predator 301, or the Honda GX390 or GX 270 and their other clones. Inappropriately, a lot of individuals end up installing the forty series the wrong way, mostly because all the tutorial articles and videos are about the thirty series and individuals assume that the forty series are installed the same way.

In fact, some videos on forty series install available can also get you confused. If you install it incorrectly, you’ll end up wearing out the belts and losing much power.

So, How Do You Do It Properly?

If the driven pulley’s movable half has a red spring, the driven pulley’s movable half needs to be positioned in the opposite direction to the driver pulley’s movable half, such that the torque converter’s cam is facing towards your engine.

40 Series Torque Converter

If you desire to install your torque converter such that the cam is facing outwards, then you’ll need to replace its red spring with the yellow spring, also known as the reverse spring. Similarly, in the other symmetrical belt systems, the torque converters like the 500 series and the 20 series all have the cam facing your engine.

Step-By-Step Guide:

  • First of all, fix the driven pulley into the jackshaft; if the spring in your driven pulley is red, then the cam will face your engine, and if it’s yellow, then the movable components will both be on the same side (opposite to your engine)
  • Slide a few washers into your crankshaft so that the driven and the driver pulleys can easily be aligned and also provides a little clearance between the driver pulley and your engine.
  • Slide the driver pulley into your crankshaft such that the fixed component is facing your engine. If the setup has a back plate and you desire to install the back plate, then you will have to bolt down the center holes on the plate into the four holes on your engine (the holes will be close to your crankshaft).
  • Bolt the driver’s outer half into your crankshaft with the bolt and lock and the flat washer that comes with this setup. (Suggested torque by Comet is 24-30 feet-lbs)
  • Mount your belt in between the pulleys.

And that is all about it; time for you to check out if everything functions fine. If your belt wearing or other issues keeps on appearing even after the correct setup, make certain to make use of the correct-sized belt, have the two pulleys seamlessly aligned, or get a better torque converter.