Chevy 496 Big Block Engine Build - The Street Brawler 496

The basis for our engine is the 454 pulled from Hunkins' Chevelle. Far from exotic, it was just a common low-compression, small-port truck motor; the kind that still shows up in junkyards and swap meets. We wanted an engine that anyone can put together in their garage, without needing a full machine shop to get it done. This is a big-block Chevy that goes together pretty much like a stock rebuild, but packing some serious punch.

Eagle has a variety of parts at different price levels, including forged cranks, H-beam rods, and forged pistons. We went with a more basic internal assembly, with a cast crank, budget I-beam rods, and hypereutectic pistons. The reasoning here was cost-to-benefit. If we were going with a high-rpm racing combo, the added insurance of high-end parts certainly adds peace of mind, but taking a realistic look at our objectives, the standard Eagle stuff is plenty stout to meet our needs. Reliability has a lot to do with rpm, and with 496 cubes working for us, there is no reason to wind the guts out of an engine this big for the street. Our plan was to let the displacement do its stuff lower in the rpm range, with a modest target of under 6,000 rpm. Shooting for a moderate rpm range dovetails with the budget approach throughout the build.

Since the Eagle internals provide practically everything needed to fill the block, there wasn't much to do on the machining front before the engine was ready to assemble. The stock block went to Andy Mitchell's Outlaw Racing for cleaning, inspection, and a bore and hone job, and that was it. It was pretty nice to walk out of the machine shop with only a $235 bill. Besides the bore prep, there was some clearancing of the block needed to accommodate the stroker crank's longer throw, and it was time to start putting the bottom end together using the all-new parts. The stroker kit went together about as easily as a stock rebuild, but the added cubes will pack a noticeable punch once the engine is completed.

Power Parts:

Cam, Induction, Heads
One of the nice things about a stroker combo is it moves the rpm range lower for a given power level, and this factor would figure in with our cam choice. Hands down, the cheapest way to cam an engine is a hydraulic flat-tappet; the only down side is that a juice cam doesn't particularly like high rev's. With the stroker's rpm range, a flat tappet is more than a viable choice; it is perfectly capable of providing the engine's needed valve action. Still, with all those cubes to feed, a healthy stick is the right call, so a COMP 292 Magnum cam was the choice. With 244 degrees duration at .050, and a .550-inch lift, the 292 Magnum cam is stout enough to feed the beast. Being a hydraulic, we could pretty much forget about it once installed. On the recommendation of cam guru and PHR contributor, David Vizard, we had this ground on a 108-degree lobe separation angle, which David swears is the cat's pajamas. (Hence, the custom part number you see in our spec chart.) Another way the hydraulic fit with our budget plans is that it is happy to work with inexpensive hydraulic lifters and a cost-conscious valvetrain. We used COMP Magnum rockers, and the stock single springs supplied with our heads.

The head choice can make or break both the budget and performance of an engine like this. Rather than mess with a stock set of small-port truck heads, a new set of iron Summit rectangular-port heads were chosen. Not only do these have a much higher capacity than late-model stock big-block heads with their 308cc intake runners, but they also come complete and ready to rock with valves, springs, retainers, studs, and guideplates. Like going with the stroker bottom end, replacing the heads instead of rebuilding stock stuff is quite a good value, especially if you consider the costs of reconditioning and upgrading a used set. The Summit heads (which are made by Dart) require longer pushrods than stock, and to determine the exact length required, it is best to mock-up the heads and measure what's required on your particular block with a checking pushrod.

Topping the heads is the induction, and here we again stuck to our lower rpm torque plan with a two-plane Edelbrock Performer RPM Air-Gap intake. Within a street rpm range, these intakes don't give much up to a single-plane in top-end power, but add big gobs of torque, making it an ideal choice for our street 496. We saved some coin on the carb, going with a swap meet Holley 750 we picked up for $75. We had the carb fully restored, modified, and rebuilt with an 850 baseplate by Performance Carburetors of Ontario, California, and came away with a great carb for about half the cost of a new piece. These guys do great work. With that, most of our build was completed with no surprises, and the finishing touch was to re-install the MSD distributor that came with the engine core, and add a set of MSD's new Street Fire wires. All in, we had about $5,500 in building the 496, an amount you can easily exceed even when rebuilding a stock-displacement 454.

Test Time
Though our engine had grown to a 496, it was a pretty basic package not far removed from what the old-school street-build guys have been doing to 454s for decades. We brought the engine to Westech Performance Group in Mira Loma, California, to put it through its paces. With a flat-tappet cam, the break-in period is critical. For added insurance, a pint of COMP's Engine Break-In Oil Additive (PN 159) was poured into the crankcase before the engine was fired and run through the dyno's automated break-in cycle. Don't skimp on the cam break-in with any flat tappet, and make sure the engine is dialed in and ready to fire before attempting to start it for the first time.

Before long, we were ready for the power pulls, and here the stroker showed its fat arm in action with torque rolling in hard right from the bottom of the pull. In fact, with some tuning of the jetting and timing, the 496 was belting out 550 lb-ft right at the bottom of the test range at 3,000 rpm. That's torque that a pump-gas 454 just can't deliver. Torque peaked at 582 lb-ft over a range from 3,800-4,200 rpm, while the engine kept making steam for a power peak of 567 hp at 5,700 rpm. The engine showed a broad power curve at a moderate rpm level-just the thing for a reliable and fun street ride. When it comes to making power on a budget, size counts, and the torque over the operating range of this engine will make it a much sweeter street mill than a smaller engine making similar power at a higher rpm, and without the low-end torque. With power this cheap and easy, what are you waiting for?