Converting SOHC to DOHC
Most people looking at this site are looking for a performance build. The first thing to consider to upgrade your truck motor is to swap a DOHC head from an Eclipse. This section currently only contains information on 6 bolt head swaps.
I did not have to drill or cap any holes in my block to do the swap. The head is from a 1991 Mitsubishi Eclipse GSX, the head gasket is from a 2.0L turbo rebuild kit and the block is from a 1991 Dodge D50 pickup. I even took a picture to proove it: 
Obviously, going SOHC to DOHC changes the timing belt configuration a bit. Lets start by listing what parts are different.
- Oil Pump Cover
- Oil Pump Gears
- Water Pump
- Water Pipes
- Crank Timing Sprockets/Gears
- Timing Belt - MD182292
- Cast Timing Parts
- Idler Pulley - MD156604
- Tensioner Pulley - MD129355
- Hydraulic Tensioner - MD308587
- Timing Belt Cover
- Timing Guards
Optional Changes:
- Bridged (1,2)(3)(4,5) Main Caps - Requires line bore machining
The Oil Pump covers look similar but upon closer inspection the timing markers and tensioner mounts differ. Below is a picture of a SOHC (top) compared to a DOHC (bottom). You have to look really closely at the details, but they are different. Alternater bracket different thicknesses, some oil passages different sizes, even the lengths of the oil pump gear shafts differ between SOHC and DOHC.
There is also a small detail that could become very bad news if you don't pay attention to it. The SOHC block's tensioner spring is mounted on a stud coming from the block. If you retain the stud to mount the front cast timing part to, it will rub the timing belt when it is tensioned. The solution is as simple as removing the stud and replaceing it with an appropriate bolt. If you're pulling your timing parts directly from a DOHC block, you'll already have this part. Here is a before and after.
© 2006 Bowman Cybernetics