I have a 3.3L sitting that I pulled out of my van, at some point I'll grab a second 3.5L/4.0 block, the real comparison will need to be made then.
The front and rear crankshaft seals are actually the same part numbers between the 3.5L and 3.3L. It appears that the 3.3/3.8 has the front tip of the crank turned down to a smaller diameter only where the harmonic balancer is. The big difference is the timing sprocket and oil pump.
- The oil pump sits behind the timing sprocket on the 3.5L
- The oil pump sits ahead of the timing sprocket on the 3.3/3.8L
The 3.5L has the area where the timing sprocket sits turned down to the same diameter as the front main seal area, while the 3.3L does not.
3.5L
View attachment 71819
View attachment 71820
And the 3.3L/3.8L
View attachment 71827
View attachment 71826
In order to run a 3.5L crank in the 3.3L, you'd need a sleeve made to fit over the crank for the 3.3L oil pump. Wouldn't be hard to make.
Alternatively, the 3.3L and 3.5L oil pump rotors are interchangeable, except that the rotors are 7.64mm thick on the 3.3L and 9.4mm thick on the 3.5L. If you were to machine the 3.5L oil pump rotors down thinner, they'd work, because they have the same outer diameter already. In that situation, you only need to key the pump rotors to crankshaft, instead of needing a sleeve.
Then you just need a key way drilled or milled into the crankshaft for the 3.3L sprocket to index into the location that was previously the oil pump drive. Easy to do yourself, I had to do this on my 4.0L.
The rods are extremely similar, but I think it's to the 3.8L.
| 3.3L | 3.8L | 3.5L | 4.0L |
| Bore | 93 mm | 96 mm | 96 mm | 96 mm |
| Stroke | 81 mm | 87 mm | 81 mm | 91 mm |
| Rod Length | 157 mm | 150.98 mm | 150.77 mm | 150.77 mm |
| Piston Comp Height | 29.7 mm | 33 mm | 38 mm | 33 mm |
| Piston Pin Diameter | 22.89 mm | 22.89 mm | 24 mm | 24 mm |
| Rod Journal Diameter | 61 mm | 61 mm | 61 mm | 61 mm |
| Big End Thickness | | | 21.69 mm | 21.69 mm |
There's some slight variety in this list with the compression height. The combustion chamber volume is slightly bigger on the SOHC than the OHV, being roughly equal to a 1mm drop in Rod Length or Piston compression height. Also, in the sizes of these 4 engines, a 1mm change in the height of the piston at TDC is roughly equivalent to a 1.0 change in compression ratio.
