MudEye

Sorry I was reading to many articles on 330 interchanging with 455.....As I was thinking of a rebuild ...What I really meant was the opposite. Will 455 heads increase the hp performance on my sbo......? I want to keep my 330. But want MORE HP.... SCOTTY MORE POWER TO THE ENGINES! CAPTAIN SHE's GOING BLOW!

MudEye

This is a rebuild project...Thanks!

olds 307 and 403

The crank would need spacers and you would lose a ton of stroke and cubic inches. The heads will bolt on but the taller 455 intake port may hang out in the air, not good. If it needs a total overhaul, there are many quality pistons for the 455 and Edelbrock or Procomp heads. Even if it has J heads and huge dish low compression pistons, the above fixes those short comings.

edzolz

If you don't know any more than this about Olds engines, don't try to build your own.

joe_padavano

Unfortunately, I must agree with this. The OP is asking some pretty basic questions and the devil is in the details.

Yes, the 330 heads will bolt onto a 455. The small block heads have MUCH smaller ports than the big block head, so this will really choke the motor and negate a lot of the HP benefits from the larger displacement. Worse, the mismatch between the BBO intake ports and the SBO head ports will cause a massive flow disruption, further negating HP. This is a REALLY bad idea.

The SBO uses 2.5" main bearings. The BBO uses 3.0" main bearings. You'll have to come up with bearing spacers to make this work. Of course, the SBO crank has a 3.385" stroke, the 455 has a 4.250" stroke. Do the math on the reduction in displacement. Also, you'll need custom length connecting rods due to the shorter stroke. This is also a REALLY bad idea.

I suggest you learn a lot more about Olds motors. There is a lot of mixing and matching that can be done. These are not the recommended ones, however.