In our quest to build a Budget g-Machine, the powerplant became a major consideration. Naturally, we have many options, so we evaluated all of them before moving forward with a plan.
Our '69 Nova project car is still equipped with the original 307ci engine, and we considered using this as the basis for our buildup, but to achieve the 350-400 hp we were shooting for on pump gas, we'd have to invest too much cash into the 307. This would put it outside of our "budget" realm. We'd be better served selling the 307 to someone in need of a decent-running candidate for a stock rebuild and applying the meager profits toward our "real" engine.
Naturally, crate engines seemed like the logical solution. Beyond the excellent offerings from mega-dealers like Jim Pace, several aftermarket companies are offering superb crate packages that would suit our needs, but we wanted to do something interesting and creative while staying within our budget. We did some homework and came up with a cool combination we think may be of benefit to many of our readers.
We decided to build a quasi-crate motor consisting of a crate short-block to get a good foundation, then top it with some Vortec heads and some good valvetrain and induction parts to wake it up some. This way, we could sidestep four-bolt mains and other money-adding features unnecessary on an engine of this caliber. We'd be perfectly content with a cast nodular crank, two-bolt mains, and powdered-metal rods, all capable of supporting our target power level in this car. We could enhance induction capability with the addition of a Crower cam/lifter/rocker kit, an Edelbrock intake, and a Demon carb.
You're saying "Wait a second, how could any of those aftermarket parts qualify their way into a budget buildup?" Certainly, Demon carbs aren't cheap, are they? How about $320, complete and ready to bolt on with an electric choke and vacuum secondaries? The Road Demon carb offers plenty of performance for that bottom-dollar price, and may be one the better new deals currently offered. The Edelbrock Performer intake for the Vortec heads (PN 2116) is also a good deal. We didn't skimp on the valvetrain, but we can justify that too. By choosing the correct cam for our particular combination, we hope to make more power than a comparably priced crate motor, and one that carries other distinctly different characteristics.
Our goals for this powerplant (beyond the obvious budget approach) were to make great power on pump gas throughout the usable rpm range, while providing a maintenance-free mill with instant throttle response. We did not wish to rely on a junkyard gamble short-block, nor did we want to challenge the local swap meet and build a one-off budget engine our readers could not duplicate. Just because we may have been able to find a pair of reworked AFRs at Pomona for $100 doesn't mean you could, and that's not fair. So, we'll show you what we did and why, and if you can beat our reliable budget-built motor with swap meet steals, go for it.
Our short-block came equipped with flat-top pistons and when teamed with our 64cc Vortec heads, would produce 9.8:1 compression--fine for pump gas. The GM pistons are a hypereutectic design, and we can run 92-octane up to 400 hp without issue.
Stepping up to the Crower cam requires us to change the timing chain and gears, too. We always prefer to run a double-roller timing set in our small-blocks, and upgrading over the factory single-link chain made us feel better. This cam drive change is necessary due to the differing diameters on the noses of the GM cam and the Crower piece. As we've explained in previous late-model ,small-block Chevy buildups, the factory cams in the new engines (including the ZZ-series of small-blocks) have a revised camshaft design incorporating a plate mounted to the block behind the cam gear. This replaces earlier designs which required shimming or a cam button to control cam walk. By choosing an earlier-design cam, we were forced to change the timing set. Stepping up to a nice double roller is hardly a penalty, so we had no problem with it.
The Crower cam has a power range from 1,500-4,000 rpm. The redline is 5,500 rpm, with 214 and 218 degrees of duration (intake and exhaust, respectively) at .050 inch, and .456 and .458 inches of lift (also intake and exhaust) at the valve with 1.5:1 rockers. We're using Crower's PN 736034 rockers, which are self-aligning units designed for use on late-model Vortec heads and boasts a 1.6:1 rocker ratio. This boosts our lift to .486 inch on the intake side and .488 inch on the exhaust. Considering the .500-inch lift limit on Vortec heads, that's plenty without being too much. The revised ratio will leave the valve opening and closing points where they are, but open the valve faster, further, and for a little longer than the 1.5:1 stock parts. It's like reinventing the cam without having to pay for a custom grind, and that's fine by us as long as the new specs fit within our design parameters.
So there you have it--our plan for a quasi-crate motor with some well chosen bolt-ons, all readily available, and affordable. What's it worth? Check the dyno chart at the end of the story--but first, follow along in the photos as we assemble our mix-and-match small-block. No custom fabrication or modifications were required, we simply teamed the parts together and took them to Jack Bayer for assembly. Jack has been building small-block Chevys as long as there have been small-block Chevys, so we knew we were in good hands. If assembling a streetable, powerful, reliable small-block Chevy is part of your future plan, and within your capabilities as a wrench-turner, this combination may provide precisely the kind of blueprint you can follow.
Our long-block carries GM PN 12513151, and comes completely assembled with two-bolt mains,
What? You're swapping out a roller cam for a flat-tappet design? Normally, we'd be going t
When swapping out cams on a late-model GM block, double check which style cam and drive yo
We chose GM head gaskets designed for Vortec use. Installed correctly, the part number sho
Getting the heads on was simple. The stock head bolts were used, since they were new and s
We've discussed Vortec rockers in previous stories, but we'll review. No guideplates are r
You can spot Vortec heads at the swap meet by looking for the triple peaks where we used t
We've also discussed GM's reusable intake gaskets for the Vortec heads before, but they're
Edelbrock's intake manifold for Vortec-style eight-bolt heads (right) carries PN 2116 and
Ignition duties will be handled by one of ACCEL's reliable electronic distributors (PN 711
We topped the engine with one of GPT300's Road Demon carbs. This 650-cfm unit is loaded wi
EM BUDGET CRATE DYNO RESULTS
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