Some Comparisons of a Chevrolet Iron Head L98 VS L31 350

I picked up a L98 out of a 89 Firebird last summer during a Pic-A-Part outing. I bought the long block with the intention of rebuilding it for Pepe. Upon tearing it down, I discovered the short block had a broken piston skirt. The previous owner had replaced the L98 camshaft with a Crane Power Max 2032 and had also done some amateur port work on the intake side of the heads. During another outing a few weeks back. I pulled a 140K mile L31 Vortec from a 1996 Tahoe.

There are some expected differences between the 2 engines and a few unexpected.

OIL PAN

I expected the truck pan to be totally different from the Firebird. They were actually almost the same shape. The L98 is in front or to the left.

The most surprising difference is that the L31 pan had a separate windage tray like a L98 Y body. If you look at the L31 pan on the right, it has two holes drilled in the pan tray for clearance of the main bolts that hold the windage tray.

HARMONIC BALANCER

The two are completely different diameters. L98 on the left, L31 on the right.

I don't know if this information is interesting, but here is a picture of the L31 camshaft with a code on the end.