Big-block or small-block--pick your poison. This argument is as old as the hills and one that often crops up and divides the Car Craft staff. "Big-blocks make more power," claim the loyal big-inch contingent. "Small-blocks are much lighter than their big brothers; big-blocks make more torque, and more torque means more traction problems," counter the small-block loyalists. "But torque moves the car," say the big-block fans. All things being equal, a big-block will usually make more power and torque, but at what cost? The small-block usually gets the nod for lower cost, easier packaging, and good output per dollar. However, big-inch small-blocks are saddled with small-block-sized cylinder heads, and even marginal big-block heads will normally flow more air. You can't beat the appeal of a fat Rat nestled between your fenderwells, but whipping up on a big-block with a small-block means major bragging rights. And so it goes.
So, we decided to use our latest automotive acquisition as a testbed to revisit this oft-heated argument. We got our hands on two Bill Mitchell Hardcore Racing crate motors: a 427-inch small-block and a 509-inch big-block. The SuperNova's 383 was temporarily tossed aside and in its place went the 427-inch small-block crate motor to begin Phase One of our test. Phase Two was accomplished by shoehorning the 509-inch Rat into the poor SuperNova for more dragstrip thrashing. Will this issue be settled once and for all? You be the judge.
What You'll Need
While they come fairly complete and already broken in on the dyno, there are still some items you will need before you can install and run your 427 or 509 crate motor.
* Flexplate: Ours was purchased from our local parts emporium; both engines take a neutral-balance flexplate
* Headers: Hedman 1 ¾-inch units for the Mouse, 2-inch units for the Rat
* Water pump: We chose to use long-style pumps for both engines, with an aluminum unit on the Mouse and an iron one for the Rat
* Pulleys: Classic Industries supplied the repro '69 396ci 6 ¾-inch two-groove crank pulley intended for use with the long water pump. Note: Typical aftermarket big-block 7 ¾-inch-diameter pulleys will barely clear the crossmember, making belt changes difficult.
* Alternator bracket: Alan Grove Components provided trick mid-mount long-pump alternator brackets for both engines
* Fuel pump: Bill Mitchell crate motors have provisions for using mechanical fuel pumps; we used Barry Grant Superspeedway mechanical pumps on both
* Dipstick: Taiwan-chrome from our local speed shop in Glendale, CA