The first question, posed by Mike Johnson of JMS Racing Engines, our talent for this shindig, was this: What kind of motor do you want? A dyno queen was immediately ruled out. I wanted a big number, but not at the expense of real-world performance. I laid it out baldly. "I'd like 600 hp-or close to it-but I'd also like just as much torque and a Kansas-flat torque band, thank you." That's not asking too much, is it?
That settled, the big question, as kicked around by Mike and yours truly for a day or two, was pretty straightforward. Should we keep a stock stroke and try to score some good heads, or should we stroke the thing and cheap out on the heads? We chose Plan B. We'd add a quarter-inch stroke to our 454 base to create a grunt-happy 496, and Mike would port a set of 049 heads for us to use. Or so we thought.
Further digging turned up a set of new GM rectangular-port heads, fully assembled and with a spring upgrade from Aerohead Racing for $1,115. Visions of those big, fat 325cc intake ports dancing in my head, I called Mike to describe my find. His response? "Hell yes, let's do it." Just like that, we got to go with both Plan A and Plan B. This battle would be fought with a big stroke and lots of airflow.
We pretty much knew we'd be using a two-bolt main core, which Mike assures us is more than adequate for this power level, assuming main studs are used. Ditto the cast crank. Forged is great, but a properly prepped cast crank can handle much more than we're throwing at it. On the other hand, another change came when we decided to rescue a 454 core that was already 0.060 over, which would create a 505ci big-block. If a big bore is good, a bigger bore is better, right?
In essence, one thing remained, and that was to spec out a camshaft with Isky Racing Cams. This thing was destined to be a solid flat-tappet cam motor from day one, oil additive issues be damned. Given my powerband desires, Mike huddled with the brains at Isky and cooked up a 'stick...which produced exactly the power characteristics I wanted.
In the final analysis, creating a setup that works is what this project was about. What we did, in short, was maximize our combo within the budget constraints. Cam, heads, bore, stroke, compression ratio; everything was right. "We wanted a long torque band that kicks in right away," said Isky's Nolan Jamora. Yes we did, and that's what we got. "It's pretty impressive," chimed in Mike Johnson. "We did our homework, and that's all that matters."
Well, not quite all; we thumped the small-block, in case you haven't noticed. With 83 more cubic inches, a 4.250-inch stroke, and heads that outflow just about any small-block head, are you surprised?
Given the budget constraints of this project, we planned on a solid flat-tappet cam from the get-go. Jeff coated our Isky 'stick liberally with Rev-Lube XP-2000 for protection during break-in; we added a quart of oil additive for the break-in cycle at Westech. | 
Camshaft Specs
Manufacturer: Isky Racing Cams
Part Number: 396-CP55 S-396/S-447
Type: Solid flat-tappet
Valve lift: 0.638/0.654 inch, intake/exhaust (1.75:1 rockers)
0.620/0.636, intake/exhaust (1.7:1 rockers)
Duration at 0.050: 259/268 degrees, intake/exhaust
Lash (hot): 0.016/0.018 inch, intake/exhaust
Lobe separation: 106 degrees | 
One of our biggest scores for this project was this set of new GM 14097088 cast-iron heads from Aerohead Racing. Originally made for Gen V 454 H.O. and 502 H.O. engines, these lungs sport an 118cc combustion chamber and, more importantly for our purposes, big ol' 325cc rectangular intake ports. As shown below, when used with the proper gasket, they'll work just fine on MK IV blocks. |