Varieties of Olds Small Blocks :: 1964 - 1990


Varieties of Olds Small Blocks

Olds 350's come in a few basic varieties:

1968 - 1972: Smaller combustion chambers, strong blocks, possibility of Nodular Iron cranks (a close second to the forged cranks that the 330's used). Four-speed 4-bbl engines had pretty decent camshafts. No EGR. Of course, if you get a W-31, you've got a pretty great engine right from the factory. The '68-'69 heads used a smaller exhaust valve than the later units. The high-compression pistons will make any of these a high-compression motor. 7/16 head bolts.

1973 - 1976: Larger combustion chambers, small intake and exhaust valves. EGR intakes, but the #8 heads were not too restrictive (compared to later units). Block is still relatively strong, with solid main webs. No more nodular iron crankshafts, but HEI ignitions on the later units are the best street setup. You need earlier heads to get high compression, even with high-compression pistons. 7/16 head bolts

1977 - 1980: Large combustion chambers, small ports, EGR, low compression. They did, however, have ½ head bolts (in common with the 403's and diesel 350's), though the windowed mains on the block make these the weakest engines to start a performance rebuild from. In reality, however, you're not likely to blow out the bottom end of this motor on the street below 6000 RPM.

There were also the D- and DX-block diesel 350's that are the heaviest duty around, and which had ½ head bolts.

[Please refer to the Blocks section as well!
[Please refer to the Heads section as well!
[Please refer to the Intake Manifolds section as well!
[Please refer to the Exhaust Manifolds section as well!
[Please refer to the Crankshafts section as well!
[Please refer to the Pistons and Connecting Rods section as well!

[ Thanks to Bob Barry for this information ]

Varieties of Olds Big Blocks

Compared to Differences
425 455 crankshaft, piston rods, and pistons
Late 400 455 bore size
Late 400 425
Early 400 425
Early 400 455
Early 400 Late 400

[Please refer to the Best Big Blocks section as well!