Buick Engine - Bulldozer Torque

Buick long known for stump pulling grunt are still alive and well, thanksthe the crew at Automotive Machine & Performance

By Steve Dulcich

Photography by Johnny Hunkins

At the height of the "golden era" of performance, the Buick name brought recognition and status. Unlike today, a world where there is little to differentiate one brand from another, choosing a GM product in the '50s and '60s meant finding your place in the hierarchy. At the top level of opulence and indulgence were the Cadillacs, while the Buick offered prestigious transportation, but at a less ostentatious level. Let the rock stars and celebs drive a Caddy, the Buick owner portrayed success without having anything to prove. Another interesting facet of the era was that, at least at GM, each division designed and produced engines of its own. The engines were as distinguished and unique from the other divisions as was the styling. It was before the time when corporate standardization led to "corporate engines," and Buicks came with a Buick engine, while Chevrolet's powerplants were only found in Chevys. It may seem

inefficient today to consider that GM was producing unique 455 Pontiacs, 455 Oldsmobiles, 455 Buicks, and 454 Chevrolets--four engines within 1 cubic inch of displacement--all at the same time. Thankfully they did, and as a result we can now revel in our favorite big-blocks of the era.

Buick, being a status brand, was highly competitive in the drive to design and manufacture state-of-the-art engines that were both refined and powerful. The seminal "nailhead" OHV engine was introduced in 1953, and it became instantly popular with performance fans in countless applications, from custom hot rods, to Mickey Thompson's four-engine drag wagon. With the cutting-edge overhead-valve nailhead, Buick was rightfully proud of the effortless torque production that was characteristic of a Buick powerplant. Fat low-end torque, and lots of it, was the perfect companion to the easy cruising and powerful Buick style. Buick capitalized on the impressive torque by designating their engines by their prodigious torque production, with names like "Wildcat 455" assigned to the 455 ft-lb 401 nailhead used in the '64 Gran Sport.

By the mid '60s, the nailhead was becoming outdated, and Buick went about designing a new series of engines based upon modern casting techniques and design trends. The result was the "modern" family of big-block Buick engines introduced in 1967. These new and thoroughly modern engines feature major improvements in the cylinder head design, with improved ports and larger valves. The new-design Buick V-8 created power potential far beyond the capabilities of the nailhead.

The pinnacle of the era of Buick performance ushered by the new powerplant was achieved in 1970, when Buick pulled out the performance stops, and stuffed the gargantuan 4.310-inch bore, 3.900-inch stroke, 455 cubic-inch mill into the intermediate GS. The GS455 in that year was available with the mighty Stage 1 455, with a conservatively rated 360 hp at 4,600 rpm, but more notably, an unreal 510 lb-ft of torque, coming in at a locomotive-like 2,800 rpm. This Buick powerplant produced more torque than was available in any production GM vehicle, and that included the best from Chevy, Pontiac and Oldsmobile. In 1970, the Buick was exceeded in outright torque only by the much larger 472 and 500 cubic-inch Cadillac engines, though even these did not match the low-end bulldozer torque of the mighty Buick.

After the high watermark of 1970, the tightening noose of emissions, fuel economy, and insurance regulations saw a progressive decline in the Buick engine. The 455 displacement was dropped after 1976, by which time the output had suffered greatly. The story may have ended there, were it not for the legendary performance of these classic machines. A loyal following of Buick enthusiasts kept the faith with Buick restoration and performance. Interest in Buicks has never waned, and these days it's possible to build Buick power like never before.

Automotive Machine & Performance in Philpot, Ky., is a shop recognized for its expertise in Buick Performance. The company primarily does Buick crate engines, and we were fortunate to have them participate in last year's Engine Masters Challenge, Popular Hot Rodding magazine's annual engine-building competition. Mike Phillips of Automotive Machine had this to say about the Buick's continued popularity: "The Buick makes big horsepower for what it is. It's a small motor compared to the other engines of similar displacement, 50 to 75 pounds lighter than the Ford or Chevrolet big-blocks. The characteristic of the motor is that it was made for an Electra 225, not for racing. The Gran Sports were such popular cars, and there are a lot of them left. Someone is needed to build these motors the way guys want them. Filling that need is what we primarily do." When asked what customers want, Mike replied: "More and more horsepower."

The Buick stroker brought to compete in the Engine Masters Challenge was built for a customer, Mike Bachorsky, for street use in a '70 Buick GS that is currently being restored. This engine's foundation is a factory-production 1976 Buick 455 block. On this particular engine, the bores cleaned up from the factory size of 4.312 inch to 4.325 inch with just a honing. Combined with a 4.325-inch stroke, the basic configuration is square, and displaces 508 cubic inches. Buicks are known for having thin blocks. Mike had this to say: "They are thin. This is a 1976-model block, which is better than the earlier blocks--the bore centers are more consistent. We sonic check all the blocks we build and this one was fairly even in bore thickness. You just have to make sure you start with a good block. The weaknesses are in the main webbing, cylinder bores, and the lifter bores. You have to beef it up everywhere to make it withstand the pressure you put on it."

Mike continued, "T/A performance makes the block girdle that just about eliminates the problem with the main webbing stiffness, but that's not a cure-all for it. We've seen some blocks split right up through the oil hole, right up the cam journal, even with the girdle. We haven't had this kind of failure happen to us." Philips speculates that some of the problem might be in how the block girdle is installed. Automotive Machine seems to have found a technique that works. The secret is in the clearances and consistently setting up and torquing the girdle during all machining operations.

For some engines built with extreme output in mind, block filling can also add a measure of insurance. Mike decided against filling on this engine, "We do it on some engines, and I was kind of torn between doing a partial fill or not. I thought because we only honed the bores and it was near the factory size on the cylinder wall this was a good block to start with, so I did not fill it. This block sonic checked really well for a production piece, with 0.140 inches of wall thickness. Anytime we fill one, we don't do it like we would a Chevrolet, we do what is called a short fill. The way the head bolts are, they go into the water jacket so far--you have to be careful."

Residing in the block is a custom cross-drilled billet crank from Moldex, which is one of the few companies that do a Buick crank. Moldex is equipped with the CNC programs to fabricate these cranks, and considering the Moldex reputation for excellence, they are a fine choice. The crank is, as expected, fully profiled, and features Buick mains, and big-block Chevy rod journals. The rod journal specification allows the use of commonly available aftermarket rods for the Chevrolet application. This engine uses a set of 6.800-inch Eagle H-beam rods, with custom JE 23cc dish reverse-dome pistons, for a compression ratio of 11.3:1. With the Chevy spec rods, the piston pin diameter is also Chevy-sized, at 0.990 inch. The rings are also JE, a set with conventional 1/16-inch widths for the compression rings, and 3/16-inch low-tension oil rings. All the bearings, including the rods, mains, and cam bearings, are coated from Calico.Capping the capable short-block is a set of T/A Stage 2 Track Eliminator heads, which feature a 14-degree valve angle. Buick expert David Wink does all the porting and modifying of the heads, and the result of the effort plays a major role in the engine's output. Wink undertook an intensive development program on these castings, playing with valve sizes to find a combination of 2.250-inch intake and 1.750-inch exhaust valves as the optimal set-up. The fully prepped heads certainly turned impressive numbers, moving a peak of 355 cfm through the intake ports. The induction compliments the high capacity of the heads. An SP2 manifold comes CNC port-matched from T/A Performance and is hand-massaged by Automotive Machine. The finishing touch is a 1095-cfm King Demon carb. Mike reports a peak recorded intake manifold vacuum of 1.1 in-hg at wide-open throttle, recorded at maximum rpm while testing.

Commenting on the heads, Mike informed us, "There's not much you can do with the port because of the pushrod location. You can't widen it on the inside because of the other port, and you can't widen it on the pushrod side because of the pushrod. So what we do is drill out the pushrod hole before we start, and we go ahead and put a brass sleeve in it. That way we can port all the way to the sleeve and we don't have to worry about hitting oil. At the center head bolt, we drill that out and put a .75-inch steel sleeve in it, so when we thin it out we still have the steel. If you thin that thing out too much, you'll actually waffle the intake port, so you have to have the steel in there. We try to keep some swirl in the heads because of the rpm we run the engines at. With these bigger street engines, we usually run no more than 6,500 rpm."

A flat-tappet cam from Lazer Cams operates the valves, and it is a fairly substantial profile, with 266/271 degrees duration at 0.050-inch tappet rise on the intake and exhaust lobes respectively. The cam's action is multiplied by a set of 1.6:1 roller rocker arms from T/A Performance. The combination yields 0.652/0.657-inch lift at the valves.

We were very impressed with the street-bound Buick's 713 hp output, and 667 lb-ft of torque. Considering that the output is achieved with a stock production block, a moderate compression ratio, and a flat-tappet camshaft, it is truly mechanical testimony to back up Buick's reputation.