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Buick 455 Engine Bolt-Ons - Epic Buick 455 Dyno Thrash

Heads, Cams, Intakes--All Part Of The Epic Buick 455 Dyno Thrash

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Buicks are pretty good, if not great. That's an opinion long held at CC dating back to the time we swapped an old Electra 225 motor into a Skylark wagon for summer fun, and then again when the Buick beat all comers in the now legendary CC shootout of all the GM corporate big-blocks.

Sadly, the state of gearhead living has changed drastically over the last five years, and even here in SoCal, the Buick 455 engine donors just aren't in the 'yards or on the streets like they used to be. In fact, when Editor Glad did finally score a junkyard 455 while planning for this latest Buick story, the block turned out to be damaged beyond repair. Instead, the engine core we used came from the voice of the industry, Dave McClelland, who keeps a few in stock to feed his original '70 GS455 four-speed convertible.

With Buick cores starting to thin out, we figure you'd better get it right when you build one, not only to preserve the breed but also to live up to the Hemi-stomping heritage with some real street power. That's what this story is here for--to deliver the facts about what works and what doesn't on a simple, budget-built 455. We prowled the Buick message boards to learn what cams, heads, and intakes were most asked about, and those are the parts we'll test here for your edification. We'll give you the dyno-proven power using multiple combinations of two cams, four intakes, and three sets of heads. This month we'll kick it off with cam and intake testing using stock iron Stage 1-style heads, and next month you'll see how the iron heads stack up against the Edelbrocks and the entry-level aluminum offerings from TA Performance. Speaking of TA, we've got to thank Mike Tomaszewski over there, as well as local Buick fan (and owner of a 9-second, naturally aspirated GS455) Bruce Kent, both of whom loaned us parts and expertise.

The Baseline Long-Block
All the testing in our stories was done with the old McClelland short-block rebuilt by JMS Racing Engines. The combo is as basic as it can get and easily duplicated. The only nonstock components in the short-block are ARP rod bolts and Speed-Pro forged pistons, PN L2353F, in a 0.030-inch overbore (stock bore is 4.3125, so our bore is 4.3425 for 462 ci). The Speed-Pro slugs are the lowest-priced forged pistons you can buy for the 455; TA Performance sells them for $429.95 a set. However, they do have some drawbacks, including an old-school 5/64-inch ring pack and a hefty 758-gram weight. Also, the dished Speed-Pros do not have valve reliefs in 'em, but TA Performance also sells precut pistons for an extra $85, and that's what we used. For just an extra $235 to $250, you could get modern, lightweight, custom forgings with 1/16-inch rings, and the extra money could be well worth the opportunity for more compression.

The Buick 455s were launched in 1970 with 10.0:1 to 10.5:1 compression, but that fell to 8.5:1 in 1971 and then to 8.3:1 before the engine was discontinued after the '76 model year. On our test engine, the compression represents what you'll get from a stock '71 to '76 junkyard 455 or what is running in your Buick right now. The Speed-Pro L2353F pistons start life with 27.8cc dishes, then add another 3 to 4 cc for the custom valve notches, bringing the total to about 32 cc. The compression height is 1.975, the stock rods are 6.600 inches, the stock stroke is 3.900 inches, and the production deck height is 10.57 inches. That adds up to pistons that are 0.045 in the hole, but JMS decked the block 0.005, so the real-world number is a poor 0.040 below the deck. The Fel-Pro Performance PN 1125 head gaskets have 4.385-inch bores and a 0.041-inch compressed thickness. Work those numbers with the 70cc chambers in the iron heads used this month and the compression ratio is just 8.77:1.

The heads we used are the stock, reconditioned units from TA Performance, and they use the Stage 1 valve sizes of 2.125/1.750 inches. The regular production 455 heads are the same casting as Stage 1 heads but use smaller 2.00/1.625 valves; TA uses the '74-and-earlier castings and opens up the valve size, just as the factory did. The '75 to '76 castings have factory 78cc chambers and are never used by TA. The '70 heads are 68 cc, and the '71 to '74 units have 71cc chambers that are milled to 69 to 70 cc during the rebuild process.

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