Chevy 496 Big Block Engine Build - The Street Brawler 496
Build A Pump-Gas 496-Cube Stroker Big-Block On A $5,500 Budget.
From the June, 2008 issue of Popular Hot Rodding
By Steve Dulcich
Photography by Johnny Hunkins, Steven Rupp
What makes a good street engine? The answer to this can vary depending on the goals of a buildup, but there are several factors that apply to a big slice of us regular-guy hot rodders. We see lots of cost-no-object buildups-you know, the thing where just the carb costs a month's pay. Building such an engine front to back costs several times more than your street project sitting in the garage. For guys with that kind of budget, there are plenty of choices, but if the spare cash is thin, all you can do is flip the page and dream. What about a big-block Chevy that uses affordable parts and hits like a wrecking ball when the throttle is stomped? That was the idea behind 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.
The Bottom End
Although we were going to keep it cheap and real, there was no intention of doing a dingle-ball hone and re-ring overhaul on this 454. The engine showed normal wear for a twenty-plus year-old piece, and the objective was a full rebuild. When you look at the balance between cost and power potential, using a stroker combo has too much going for it to pass up. Considering the used core needs crank and rod reconditioning, boring, and new pistons just for a stock rebuild (not to mention re-balancing), a stroker kit becomes pretty attractive. For $1,249 with bearings, an Eagle stroker kit is a real bargain for the extra 42 cubic inches. When you subtract out the cost of the pistons, rings, a crank grind, rod reconditioning, bolts, balancing, and bearings for just a stock 454 build, a 496 combo is pretty hard to pass up. A stroker is the fast path to massive torque, and the economics just make sense. Add in the fact that the stroker pieces are matched, balanced, and ready to go; it sure looks attractive compared to hauling the old parts in and having to wait while they are re-worked.
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.
There is no need for an exotic...
There is no need for an exotic starting point if you are building a street big-block Chevy. If you have a good core to work with, like this 454 truck block pulled from Hunkins' '68 Chevelle, a stout engine can be built on a budget.
The key to a long-lasting...
The key to a long-lasting and strong-running street engine is bore prep. After boring to within .005-inch of the final bore size, Andy Mitchell of Outlaw Racing Engines hones with a No. HU123 stone to .002-inch under, and then to size with a JHU 625 stone, and completes the prep with a plateau brush. This will give an ideal surface for moly rings.
One of the nice things about...
One of the nice things about getting a complete rotating assembly like this from Eagle is that the balancing is done, saving the cost of custom balancing and making the stroker kit ready for assembly.
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.
As far as results for the...
As far as results for the dollar spent, nothing equals value like a stroker kit. This complete Eagle assembly relies on a cast crank, I-beam rods, and KB pistons. Not top-of-the-line, but in line with our budget, and plenty stout for a street-storming 496.
While a forged race crank...
While a forged race crank might be on most guys' wish list, a quality cast crank is plenty durable for a lower-cost street engine. Note the nice fillet radius on the crank journals, and the well-detailed oil passage chamfers.
With a big-inch engine turning...
With a big-inch engine turning moderate rpm, there is no reason to go wild with race parts inside. Good quality rebuild parts like Clevite P-series bearings and Perfect Circle rings will be more than up for the task, and offer a good long service life.
Similarly, KB hypereutectic...
Similarly, KB hypereutectic stroker pistons are an inexpensive way to fill the bores, and are right on target for our street-bound intention. The KB pistons offer tighter piston-to-wall clearance than a forged piston, providing quieter operation and lower oil consumption. With the KB's slight dome and our 119cc combustion chamber, we arrived at a pump-gas friendly 10.25:1 compression ratio.
Our Eagle stroker kit came...
Our Eagle stroker kit came with Eagle's I-beam capscrew rods. There are many advantages here compared to a piecemeal stroker, or rebuilding with stock rods. The fresh forgings feature ARP fasteners, bushed small-ends, and are ready to go for less than you can spend upgrading an old set of OEM rods.
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.
With any stroker assembly...
With any stroker assembly it is important to mock-up the bottom-end parts and check for rotating clearance. Notching the bottoms of the cylinder bores is normally required to clear the internals. The block is marked and cut as required. Don't worry, there is no coolant jacket in the vicinity of the bottoms of the bores.
Before starting the assembly...
Before starting the assembly of the engine, it is best to pre-assemble the rods, pistons, rings, and bearings for each hole. Make sure that the orientation of the piston on the rod is correct before securing the piston pin with spiro locks.
There are more exotic and...
There are more exotic and expensive choices out there, but for the lower rpm range of a big-inch street engine, a flat-tappet hydraulic cam is the lowest-cost alternative, and offers plenty of performance along with maintenance-free operation. A COMP 292 Magnum hydraulic is a healthy stick, with 244 degrees of duration at .050, and .550-inch lift-well within the acceptable .600-inch lift range of our Summit head's valvesprings.
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.
COMP's standard hydraulic...
COMP's standard hydraulic lifters (PN 821) are all that is required if the lifters will be run with preload, as is typical of a street engine. If the lifters will be run at zero lash, COMP's Magnum anti-pump-up lifters are required.
Engine builder Tim Lee likes...
Engine builder Tim Lee likes to start the final assembly with the camshaft. Carefully slide the cam in to avoid scoring the cam bearings, and make sure the cam is well coated with assembly lube-Royal Purple Max-Tuff synthetic assembly lube in our case.
Next, the bearings and rear...
Next, the bearings and rear seal are put in place in the block, again using plenty of quality assembly lube.
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?
The factory two-bolt block...
The factory two-bolt block and the stock caps are plenty durable for an application like this, but it is a good idea to upgrade the main fasteners. Tim went with a set of ARP capscrews for a little extra security here.
With the camshaft already...
With the camshaft already installed, the timing set should go on before filling the bores. A standard Summit timing set does the job, and the timing cover can be installed next to button up the front of the block.
Since the rods/pistons/rings...
Since the rods/pistons/rings were already prepped and ready to go, it took no time to install all eight slugs. A pliers-style ring compressor also helps speed up the job.
|WHERE THE MONEY WENT
||$600 (market value)
|Eagle 496 stroker kit
|Double-roller timing set
|Standard volume oil pump
|Oil pump pick-up
|Deep sump oil pan
|Master gasket set
|Expansion plug set
|Oil pump driveshaft
|Hardened pushrods (int.)
|Hardened pushrods (ex.)
|Assembled iron heads
||$645.95 x 2
|Spark plugs (8)
|Aluminum water pump
||n/c (came w/core, Summit price $306.60)
||MSD Street Fire 8mm
||$495 (core plus rebuild cost)
|Carb fuel log
|Carb stud kit
|Accessory bolt kit
|Engine paint (2 cans)
Summit iron heads are an economical...
Summit iron heads are an economical way to deliver decent airflow to a big-block Chevy. These heads come pre-assembled with springs for a hydraulic cam, requiring only the installation of studs and guideplates. A set of Fel-Pro PermaTorque head gaskets provides the seal.
The best way to determine...
The best way to determine pushrod length is to mock-up the valvetrain using an adjustable pushrod and measuring the length directly with a caliper. The rockers are economical COMP Magnum 1.72:1 units, which rely on an OEM-style ball fulcrum, and have a roller tip.
Waste not, want not; the Melling...
Waste not, want not; the Melling oil pump was a take-off from Hunkins' Howitzer 496 big-block project that dropped the pick-up tube due to a failed tack weld after it was installed in the car. The tube was securely brazed this time around.
|Balancing of rotating assembly (included in Eagle kit price)
|Block bore and hone
|Parts and Labor Total:
Up top, an Edelbrock Performer...
Up top, an Edelbrock Performer RPM Air-Gap is the ideal intake for high torque within the engine's intended rpm range. A bead of silicone sealant replaces the end rail seals for intake installation.
Significant savings can be...
Significant savings can be made on the engine's ancillary components. A Holley 750 carb was purchased at the swap meet for $75.
Rather than bolt-up the used...
Rather than bolt-up the used carb and pray, it was sent to Performance Carburetors of Ontario, CA, for a full overhaul, including an 850 baseplate, refinishing, a rebuild, and calibration with top-quality parts. The result is an awesome street carb at a reasonable price. Including the swap meet score, we've got $495 in it.
496 CHEVROLET BIG-BLOCK SUPERFLOW 902 ENGINE
DYNO TESTED AT WESTECH
|CYLINDER HEAD FLOW
No one realized it when the...
No one realized it when the 454 was pulled from Hunkins car, but hiding under the grease, the engine had an MSD Pro-Billet distributor installed by the previous owner. Of course, this unit was re-used after a good cleaning.
On the dyno, we had no surprises,...
On the dyno, we had no surprises, and just had to break-in the engine, tune the timing, and with a jet change, the engine was dialed in for an easy 568 hp at 5,700 rpm, and a substantial 582 lb-ft of torque at a stump-pulling 3,900 rpm.