Chevy 350 Vs. Oldsmobile 350: How Are They Different?

Oh, General Motors, you practically went retired of your measurement to confuse group pinch your motor displacements. We've already talked astir really nan Chevy 350 and Pontiac 350 are wholly different engines, but there's besides nan Oldsmobile 350. Oh, and nan Buick 350, which was really a 349, but what's a cubic inch betwixt friends? 

Right now, let's attraction connected nan Oldsmobile 350 and Chevrolet's first-generation small-block 350. We'll commencement pinch nan astir basal favoritism betwixt Chevrolet and Oldsmobile V8s: Chevrolet ne'er converted its 350 to tally connected diesel (though Chevy did usage nan Olds diesel successful immoderate pickups). Any chat of Oldsmobile 350s yet gets astir to nan diesel, but earlier digging successful excessively deeply, cognize that nan Olds diesel V8 isn't that bad. Well, depending connected nan twelvemonth and proprietor maintenance, astatine least. 

Here's immoderate speedy Chevy V8 history. In 1955, nan small-block 265 Chevy V8 debuted to a chorus of cheers arsenic Chevrolet took backmost nan income crown from Ford. The "mighty mouse" centrifugal grew galore sizes, from 283 cubic inches to 327, 350, and beyond, reaching arsenic precocious arsenic 400. It stayed successful accumulation pinch various refinements until it was replaced by nan LS engines successful 1997. The 350 Chevy small-block had a 4-inch bore and 3.48-inch stroke, and it was eventually blessed pinch aluminum heads.

The Oldsmobile 350 began life arsenic a 330, which replaced nan borrowed aluminum-block Buick 215 V8 successful 1964. Like Chevy's V8, nan Olds V8 utilized an robust block, though its nickel contented was higher than Chevy's blocks for greater strength. It sewage punched retired to 350 cubes successful 1968 and 403 successful 1977. 350 versions utilized a 4.057-inch bore and 3.385-inch stroke, and dissimilar Chevy's V8, they always had heads of robust from nan factory.

Unfortunately, Olds cranks went from forged alloy to nodular robust erstwhile displacement accrued to 350 cubes. Worse, successful 1977, nan blocks were Swiss cheesed and formed thinner to make them lighter. Portions of the main base bulkheads sewage "windows" wherever formerly location was formed iron. (I'm trying not to opportunity nan blocks were butchered, I really am.) You tin reconstruct immoderate bottom-end spot by converting a windowed Olds artifact from two-bolt to four-bolt mains, but why? Early non-windowed blocks are a overmuch amended starting constituent for capacity modifications. Should you insist, usage four-bolt main caps pinch angled bolts truthful they don't flick into nan windows.

To beryllium fair, Chevy hasn't ever made mini blocks pinch spot successful mind, either. Plenty came pinch puny two-bolt main caps alternatively than burly four-bolt caps, which are preferred for bottom-end strength. There are exceptions, for illustration four-bolt 400 blocks being weaker than two-bolt versions, but we're speaking generalities here. Still, hot-rodders build two-bolt rodent motors to scope 500 hp, truthful they're not arsenic compromised arsenic precocious '70s Olds 350s. 

It's a shame, because Olds 350s started retired strong. The L74 successful nan awesomely-named Oldsmobile Rallye 350 reached a friends nod-worthy 310 hp, and the 1968-1970 W-31 reached 325 hp astatine 5,400 rpm. Burly arsenic it was, moreover nan W-31 was eclipsed by nan 1970 Chevy 350 LT-1 pinch its 370 hp astatine 6,000 rpm.

Strangely, mini and ample displacement Oldsmobile V8 blocks are practically identical isolated from for platform height. Whether you sewage a 455-powered 442 successful 1970 aliases a 307-powered Custom Cruiser successful 1989, nan bore halfway spacing was 4.625 inches. Chevy V8s person to beryllium contrarians, though; its small-block's bore centers are 4.4 inches isolated while nan large block's bore centers are 4.84 inches apart.

This brings america to 1977's LF9 diesel 350, which you batch rated arsenic 1 of nan worst engines. To Oldsmobile's credit, they didn't conscionable return nan state 350, crank up nan compression to 22.5:1, seal nan spark plug holes, and telephone it a day. The crankshaft base diameters gained a half-inch of girth. Blocks were bolstered, connecting rods became beefier, and pistons sewage alloy inserts to support nan apical compression ring. New heads were installed, nan camshaft was upgraded to Conkerall iron, and nan lifters utilized an exotic tungsten-titanium alloy. This wasn't enough, though.

After scores of caput gasket failures, injection failures, camshafts going flat, and main base caps pulling loose, Oldsmobile worked to reside those problems. Debuting successful 1981, nan caller DX motor had improved gaskets, strengthened and lengthened caput bolts, decently installed main headdress bolts, and a roller hydraulic lifter setup. It moreover had a water-in-fuel sensor since nan motor debuted without a h2o separator. But nan harm to its estimation was done, and GM dumped nan Olds diesel V8 successful a shallow sedate successful 1985 conscionable erstwhile it sewage good. The gas-powered 307 cube type limped connected until 1990 and was still carbureted because improving that motor would person been for illustration giving antibiotics to corpse.

Chevrolet's small-block besides suffered its stock of indignities. It sewage sidelined successful favour of a Lotus-designed, Mercury Marine-built DOHC V8 for nan C4 Corvette ZR-1 (which royally peeved Chevy engineers). The 400 motor sewage inadequate cooling and atrocious heads that were prone to cracking, and successful 1975, versions of nan 350 wrong Corvettes had a shockingly paltry 165 hp. But Oldsmobile's 350 was done overmuch dirtier connected basal levels.