Your street motor should share many of the characteristics of an MMA or UFC opponent, whether it's for the local cruise, the all-out open drag nights at the track, or even the everyday haul. And you can get the job done with off-the-shelf components. The days of super-custom engine builds with race-gas compression are all but gone in the today's street cars. Virtually every part is available over the counter, which brings the cost down, making such an engine build that much more realistic. Having the opportunity to tag along on an engine build, we wanted to illustrate how easy it is to make gobs of power.
As you may have already guessed, this isn't your average 454. In fact, it's an even larger 496 with a pump-gas-friendly 10.25:1 compression. While other options could have us wringing out a short-stroke small-block till all ends of the rev band, an easier option was to piece together an existing 496 short-block for the Bel Air we had in mind. Not only will the motor live longer with fewer revs, but it will have the benefit of more inches, and power will be on tap virtually everywhere in the rpm band.
Now, with any street-specific motor build, certain perimeters must be met. It has to be easy on the budget, must run on pump gas, and must produce useable twisting actions without wringing the pumper out of breath to do so. Plus, ours had to fit under the stock hood of a very clean '66 Bel Air. All in all, when you can get it to look exactly like the factory 425hp 396 big-block it came with as a factory option, kudos to you.
We met up with John Barkley and whipped up a ground-pounding, 600-lb-ft big-block factory lookalike out of his garage. We began with an original GM four-bolt main block, an Eagle rotating assembly with a 4340 steel crank, SRP pistons and rings, a Melling oil pump, and a Moroso pan-with ARP bolts throughout. It also has the benefit of a pair of large aluminum 320cc lungs from RHS, a complete Comp Cams valvetrain with a Thumpr hydraulic roller camshaft, and lifters to boot. We even utilized faux intake bolts, making the Weiand Stealth manifold look factory. In true CHP fashion we strapped the big-block on the engine dyno at Vrbancic Racing in Ontario, California, and put the 496 through its paces. And now here's an easy-to-reproduce recipe, should you want to whip up this combination yourself.
Churn out 570 hp and 600 lb-ft from our RHS-headed 496
With a diesel-like torque curve, it's the perfect motor for the street
Our build primarily consisted of adding a competent top end to satisfy the bottom. The blo
To keep the compression low but still take advantage of the squeeze, the deep holes were f
Before the RHS cylinder heads went on, we installed our Fel-Pro 4.580-inch-bore head gaske
Breathe Deep Don't let the orange paint fool you. These are fresh-out-of-the-box aluminum
To fasten the cylinder heads down, following the instructions from ARP, we installed the h
In some cases the pushrod guideplates will have to be clearanced. Our situation called for
1. Wilson 1-inch tapered spacer. The Black anodized piece straightens out and helps atomize the fuel before it reaches the chambers. An affordable way to free up those last few ponies.
2. Cylinder heads are RHS 320cc aluminum pieces. Each comes complete out of the box for $1,020. Exhaust ports are raised 0.500 inch and come predrilled for front accessories.
3. Straight from the box with almost no jetting, the carburetor performed flawlessly. While the carb came with 79/79 primary/secondary jets, we ended up only jetting the secondaries to an 81.
4. Pertronix billet distributor with Flame-Thrower II ignition coil. If you already know what kind of motor you're running, call Pertronix ahead of time to set up a custom distributor curve.
5. Set of eight Zex spark plugs. Their heat range kept our big-block happy on the dyno, which meant there was no detonation or knocking. These feature a 0.708-inch reach and three electrodes for better spark distribution.
6. YearOne tall chrome valve covers for '65-87 big-blocks. While they appear stock, they're actually 1/2-inch taller to accommodate the use of roller rockers. They don't have the slant for power brakes, either.
With the heads on, we slid in our Thumpr cam from Comp, chosen for its 2,500- to 6,100-rpm
For ease of maintenance on the street, we also selected a set of Comp hydraulic roller lif
Next we installed the lower timing gear and upper cam gear with the double-roller chain. W
With the cam in, we could adjust for thrust. Barkley derived a failproof method for measur
Designed for street performance machines running up to a 4.250-inch stroke that see occasi
Due to the cup height on our hydraulic rollers, our pushrods were a bit shorter than usual
When it comes to the valvetrain, Comp has it. To complement our camshaft and lifters, we a
We laid down the Fel-Pro one-piece oil pan gasket and applied a layer of silicone on top.
Our Weiand Stealth intake manifold was a perfect match. The dual-plane configuration has a
Next we installed our Pertronix billet distributor and Flame-Thrower II ignition coil. We
To supply the big-block with sufficient fuel, we topped it off with a Holley 950 HP. Updat
|THE RUNDOWN |
|Combustion chamber volume ||112 cc |
|Intake runner volume ||320 cc |
|Exhaust runner volume ||135 cc |
|Intake port ||Rectangular |
|Spark plug ||Angle |
|Intake valve ||2.250 in. |
|Exhaust ||1.880 in. |
|Max. valve lift ||0.600 in. |
|Springs ||Dual 1.509 in. |
|THE SHOPPING CART |
|MFG ||DESCRIPTION ||PN ||COST |
|ARP ||12-pt cylinder head bolts ||135-3703 ||$92 |
|Comp Cams ||Thumpr hydraulic roller camshaft ||11-602-8 ||264 |
|Hydraulic roller lifters ||854-16 ||432 |
|Ultra-Gold 1.7:1 roller rockers ||19021-16 ||273 |
|Magnum pushrods ||7663-16 ||117 |
|Fel Pro ||Intake gasket ||1211S-3 ||33 |
|Oil pan gasket ||Z1884R ||38 |
|Head gasket ||1075 ||80 |
|Holley ||4150HP 950 cfm ||0-80496-1 ||715 |
|Moroso ||Big-block oil pan ||20403 ||248 |
|Pertronix ||Billet distributor ||D100700 ||230 |
|Flame-Thrower II coil ||45011 ||34 |
|RHS ||Pro Action 24 aluminum cylinder heads, complete ||11001-02 ||2,040 |
|TCI ||Rattler front balancer ||870006 ||384 |
|Transdapt ||Big-block timing cover ||9914 ||37 |
|Vrbancic Bros. Racing ||Dyno test and tune ||N/A ||500 |
|Weiand ||Stealth dual-plane manifold ||8018 ||197 |
|Wilson ||1-in. tapered 4-hole spacer ||004110 ||128 |
|YearOne ||Reproduction 396 valve covers ||NP503T ||56 |
|Zex ||Spark plugs, set of 8 ||82003-8 ||53 |
| ||TOTAL ||$5,951 |
|Fuel ||91 octane |
|Timing ||36 |
|Jets ||79/81 |
|Spacer ||Wilson 1-inch |
|Max. horsepower ||570 |
|Average horsepower ||471 |
|Max. torque ||600 |
|Average torque ||583 |