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A 500hp 1973 Mercury Comet Quest For 10s

A 302 ford, A cast crank, homemade efi, 500 hp on junk gas, and the Quest For 10S

Photography by , , John Baechtel

Mix one part rockabilly with an equal helping of gearhead fabricator, stir vigorously, and what pours out is Tom Habrzyk. The guy looks like Brian Setzer but plays the small-block Ford, twisting them till they scream. A Polish exchange student who barely spoke English 10 years ago, he's going to school while spinning wrenches for pennies, driving a primered '58 Fairlane every day, and setting motorcycle land speed records at Bonneville and El Mirage. It's as American as baseball, hot dogs, apple pie, and a dire need for a 10-second '73 Mercury Comet. And not easy 10s, but normally aspirated with a tiny 306ci Ford on pump gas.

Tom turns wrenches at Westech Performance Group, which readers will recognize as one of this magazine's favorite dyno haunts. Tom runs the chassis dyno, but his job also gives him insider access to a SuperFlow engine dyno. That lets him quantify progress but doesn't make the construction any easier. Like most car crafters, Tom doesn't have a pile of money, and he works virtually every spare minute flogging his combination. That means he's able to share lots of information as we follow his quest, this month with the engine buildup, and next month with an in-car flog.

Roots

The whole deal began four years ago when Tom traded a clapped-out '86 Mitsubishi pickup for a Comet with a sick six. Since then he's done all the work on it himself including the paint and rollcage. The V-8 swap began with a $1,000 EFI 302 yanked from a '93 Ford Explorer with all the factory wiring, sensors, and distributorless ignition. Initially the electronics were set aside as Tom gave the Explorer heads a mild port job, stabbed a Comp Cams 266 Extreme Energy cam, and topped the 302 with a Victor Jr. and an 850 Demon to make 400 hp. It only made 388 hp with an Edelbrock RPM Air Gap dual-plane, but that manifold had better low-end and led to the combo's best e.t.: 12.80.

Tom was hooked, and wanted another 100 hp. His strategy included fuel injection, but with an aftermarket controller to easily tune the fuel and spark curves. The short-block was also rebuilt, dumping the stock rods in favor of stronger Scat 4340 I-beams with 3/8-inch bolts and topping them with SRP's budget forged flattop pistons (PN 138734). Tom had the cast crank pins spun 0.020 inch undersized. The block was decked, then the cylinders were torque-plate honed to seal the 1/16-inch Federal-Mogul rings and standard-tension oil rings. Tom tried low-tension oil rings, but oil seemed to be getting into the chambers at part-throttle, so he went back to standard-tension. The 306-incher is buttoned up with Speed-Pro bearings, Fel-Pro gaskets, and an 8-quart Milodon pan.

Heads First

With a 500hp goal, he knew it was time to invest in cylinder heads. Cheaping out on heads only mellows the results, so Tom stepped up for a set of Airflow Research 185 CNC heads with 2.02/1.60-inch valves. Because it's troublesome to generate high compression with small-cube engines, Tom had AFR angle-mill the heads for 51cc chambers (58, 61, or 69 cc's are standard). Combined with an amazing 0.015-inch-positive piston deck height (the pistons stick out of the bores) and thin 0.039-inch-thick Fel-Pro head gaskets (PN 1011-2), Tom was shooting for the tightest quench area and smallest combustion space he could create. This resulted in an incredibly tight piston-to-head clearance. In theory he's got around 0.024 inch; piston rock trims the piston clearance to far below 0.020 inch, but so far Tom has had no problems with the pistons smacking the heads. Chalk this up to decent 1.7:1 rod-length-to-stroke ratio and a short stroke, reducing both piston rock and piston speed, respectively.

The 2.02 intake valves, angle-milled heads, and not enough exhaust-valve-to-piston clearance necessitated cutting deeper 12cc valve reliefs in the SRP pistons. All this eventually created a 10.2:1 compression ratio that, with this incredibly tight quench and active chamber, works very well with California's miserable 91-octane premium pump gas. As Tom says, "It's never detonated--and I've tried."

Camology

After much counting of fingers and toes, Tom decided on a single-pattern Comp Cams hydraulic roller with 244 degrees of duration at 0.050 and 0.601 inch lift using 1.6:1 roller rockers. The idea was to save a couple of dollars by reusing the factory roller tappets. Tom also decided to test a set of the new Comp Cams beehive valvesprings that promised to control valve action at his high engine speeds by taking advantage of the springs' smaller, lighter retainers. The conical springs look spindly but offer as much or more overall pressure as an entry-level dual spring.

Electronic Ram

To top all this off, Tom wanted something different for the induction system and began by fabricating his own using a Weiand small-block Windsor tunnel-ram as the base and then grafting his own aluminum sheetmetal lid using an Accufab oval throttle-body. The throttle-body exhibits a nose-down attitude that Tom was forced to include to clear the Comet's low stock hood line. Using homegrown fabrication, Tom adapted FAST EFI fuel rails and injector bungs into the manifold base, then used FAST 36 lb/hr injectors.

For his own edification concerning the carburetor versus EFI debate, Tom compared his homebuilt setup to a Victor Jr. manifold and a 750-cfm Mighty Demon carburetor and saw virtually no difference in peak horsepower between the two. The EFI's longer tunnel-ram runners did improve torque slightly over the carb'd intake's shorter runner length.

On the electron-swapping side of things, Tom added a FAST box not only for the luxury of finite changes to the fuel and spark curve, but also so he could integrate the basic Ford distributorless ignition to which he added eight separate MSD coils to deliver a solid ignition strike to each cylinder even at 7,200 rpm. An MSD Digital 4 Plus CD box was added mainly to employ its launch-rpm control once the engine found its way in the car.

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