It's a generally accepted fact that no one region in the country has a monopoly on drag racing ingenuity. Colorado, though better known for its skiing and beautiful mountain scenery, has also produced some outstanding Mopar racers. Master machinist Don Hackenberg is among them. In his heyday, he was a major player in NHRA's Modified Production ranks. Now in his mid-sixties and semi-retired, Don's skills and competitive instincts are alive and well. so when a certain special Chrysler aluminum small-block came into his possession, the wheels began to turn.
Enter racer Mike Molgard. Don and Mike had collaborated on an earlier small-block Mopar engine project, and when Mike walked into the shop and saw the block, he began asking questions. The two of them put their heads together and decided they were looking at the basis for a perfect drag racing engine. The result is a hybrid that's part circle track, part drag racing, and all small-block Mopar. Arguably one of the more unusual Mopar drag race engines we've seen to date.
Don's home-based shop houses a lot more sophisticated machinery than one would expect and is a perfect match for the car for which the engine was destined. Mike's turquoise '65 Belvedere looks for all the world like a 14-second street/bracket car. It's all steel, sporting the full factory interior including the back seat, and the battery is still in the front. In that configuration, it ran a 10.54 quarter-mile e.t. with a 395-inch cast-iron small-block, eliciting lots of puzzled looks from spectators in the pits. For a while, Mike considered a big-block, but the decision was made to stay with a small-block. It would be a pioneering effort, but the result would be totally unique, offering a level of performance normally only available from a big-block.
The block casting is genuine Mopar (PN 4532711), but there most of the similarities end. For one thing, it's all aluminum and even the most basic accessories, such as the front timing cover and oil pan, had to be custom fabricated. Even some basic technical aspects of the oiling system had to be worked out, which proved to be more challenging than expected. At one point, Don cranked up his machines and built his own distributor from scratch out of a solid piece of billet aluminum. Try that sometime in your home workshop!
The history of the block is interesting in itself. Although fabricated of light weight aluminum alloy, it was judged too heavy by the World of Outlaws circle track racers for whom it was designed and was scrapped by Chrysler in favor of a lighter casting. The source of the heaviness can be attributed to the fact it was designed like a smaller version of a Top Fuel block, replete with all sorts of reinforcing ribs. Many insiders on the circle track circuit maintain it's a better block than the one they now use. Among other heavy-duty features, it is a windage block featuring a kick-out on the passenger side to divert oil from the crankshaft, thus reducing parasitic horsepower loss.
A high-rpm aluminum race engine requires durable components. Lightweight (440 gram) CP aluminum-alloy pistons were used because of excellent quality, and can tolerate a fairly tight .0045-inch piston-to-wall clearance. The rings used are .043-inch in the top and .043-inch in the second groove in conjunction with 3mm low-tension oil rings. "Drag-wise, it's like having no rings at all when there's no compression on the top ring," said Don. Pistons are gas-ported to provide maximum ring seal when it is most needed. The compression ratio, at about 13.8 to 1, is fairly conservative by today's race engine standards.
The stroker crankshaft is from Mopar performance (PN P5007252), and has had the journals machined down from 2.25 to 2.00 inch to match a common Chevy small-block size. Mike found an excellent deal on a set of GRP alloy rods with that dimension, and since that size offers so many bearing choices, they decided to go with it. At 6.46-inch in length, the rods are quite long. Even with the 4-inch stroker crank, the roomy crankcase eliminates the need for any grinding for clearance. ACL bearings with a calico coating were used throughout. Pro-Gram steel billet caps are used to help keep the high-winding engine together. The cylinders were bored over-sized and finish-honed to a final dimension of 4.125-inches, yielding a final 427ci displacement. The plateau wall finish is similar to a traditional mirror finish, with a residual super-fine crosshatch that knocks off microscopic high spots and ensures an excellent ring seal.
A parts connection in New Mexico turned up a mint set of W-8 aluminum cylinder heads left over from the NASCAR Craftsman Truck series, complete with Manley titanium valves with 2.150-inch intake and 1.65-inch exhaust valves. The heads were privy to a full five-axis CNC porting by Chapman Porting Service in Salt Lake City. Also included was a complete Jesel valvetrain setup. Valve seat angles are, as Don puts it, "pretty much a full radius with a 45-degree angle in there somewhere."
A consultation with Chris Mays of Competition Cams yielded a promising profile, carrying PN CRS1844/4082 R108.0. It's a roller grind with .739-inch lift on the intakes and .704-inch lift on the exhaust lobes. The duration is 282 degrees on the intakes and 280 degrees on the exhaust at .050-inch. Lobe separation is 108 degrees, but the cam was installed at 104 degrees to help the bottom end. (This will probably be changed... more about that later). It's important to note this is not an extremely radical grind, but rather a practical bracket cam designed for consistent performance and repeatability.
There were no factory lifters available for the block, and nothing from the aftermarket was available with the exception of some high-end units that cost $125 apiece. They were top-notch, but just did not fit into the budget. After consultations with Dave Crower of Crower Cams, it was determined that a variation of their lifters for a NASCAR SB-2 small-block Chevy with a diameter of .904, as opposed to the NASCAR Chevy's .875, would work with a little adaptation. Namely, the tops of the lifter bore bosses had to be machined down about a quarter-inch, so the link bar between the lifters would clear the block. High-tech Comp Cams pushrods with through-the-center oiling are used.
Don machined a custom valley cover for the engine, as none was available either from the factory or in the aftermarket. The block has no provision for a water pump, so a Meziere pump was fitted to the lower radiator hose to handle the coolant pumping chores.
It was also up to Don to build his own oil pan. He dubbed it the "origami oil pan" after the Oriental art of folding paper because that's the way he designed it-with paper templates and a lot folding. It was fabricated from a single piece of aluminum to minimize the amount of seams that required welding. Once his cardboard oil pan fit properly, Don recreated it in aluminum. A beefy external oil pump by Peterson Fluid Systems ensures adequate lubrication flow for the high-winding small-block.
After much research, a potential problem was pinned down at the diameter of the holes that limit the amount of oil delivered to the lifter galley. The strength of the oil pump was such that it evacuated virtually all the oil from the bottom end at high rpm. This would leave insufficient lubrication for the crank, rods, and cylinders. Once the hole size was reduced to the correct diameter, the problem was averted. An ATI harmonic balancer was used, both for its rebuildable features, as well as its lighter weight.
Also on the list of parts that had to be custom made or adapted were valve covers. To fill the need, Don simply ordered an assortment of valve cover gaskets from the local parts store and tried them one by one in different orientations until something close was found. After many test-fittings, it was determined that FE Ford valve covers, mounted backwards, required only the relocation of two holes to make them fit the application. A set was located at a local swap meet, the Ford logo machined off, and the engine was one step closer to completion.
Topping off the engine is a Mopar Performance M-1 manifold with a DaVinci modified Holley carburetor rated at 1,000 cfm. Earlier testing with a 1,000-cfm vacuum-secondary Holley delivered inconsistent results, and a 950-cfm Holley double-pumper was substituted. The double-pumper could not match the vacuum-secondary's elapsed times, but consistently delivered 5 mph more in top end. The DaVinci-modified Holley seems to deliver the best of both. A heavy-duty Barry Grant fuel pump delivers the fuel from a custom baffled stock gas tank via a half-inch braided stainless steel line.
The job of exhausting the spent gases falls to a set of vintage Direct Connection 171/48-inch headers originally made for the W-2 heads. In order to work with the W-8's, adapter plates had to be fashioned. Rounding out the powertrain is a high-stall converter by Dynamic Converters, a Pro-Trans Torqueflite featuring lightweight aluminum internals, and a 5:13 Dana 60 rearend with 1011/42-inch-wide Hoosier radial slicks. Altogether, the combination weighs 3,585 pounds with Mike at the wheel.
As stated earlier, pioneering a totally new engine combination virtually guarantees some surprises. The wheelstanding starts and 8,000-rpm shifts are pretty much as predicted. What was not expected was the torque from the small-block would be sufficient to break the 1011/42-inch tires loose in high gear. At first, Mike thought that something was coming loose in the rearend, because simple logic said there's no way a small-block-any small-block-could do that. But when Don Hackenberg carefully scrutinized the next few runs, it became obvious the tires were indeed breaking loose, even across the finish line. This tendency toward rear-steering is disconcerting, not to mention dangerous.
So, although the original premise was to keep the car limited to a 1011/42-inch slick, it's obvious that a mini-tubbed rearend treatment and a bigger tire was an absolute must to keep the car going straight. In addition, the camshaft would be retarded somewhat from its present 104-degree setting, since it turns out the bottom end really didn't need the help after all.
Even with the intermittent traction problems, the new combination has produced 1.36-second 60 ft. times and a best quarter-mile e.t. of 10.26 at 131.86 mph. This was at a 2,200 feet elevation with windblown sand on the track surface.
Recently, the potent Belvedere ran a 6.24-second eighth-mile with a trap speed of 111 mph, which, if you're familiar with eighth-mile times, is really hauling for a small-block in a heavy car.
Just as it sits, its 8,000-rpm shift points and unexpected wheelstands make it a real crowd-pleaser; a testament to the ingenuity and high-quality effort that Mike and Don have put into their home-built masterpiece. Though their thinking-outside-the-box engine choice resulted in some difficulties along the way, the result is a refreshing change from the normal big-block approach to horsepower. As poet Robert Frost once put it, "I took the path less traveled by, and that has made all the difference."