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1973 Mercury Comet -The Quest For 10s

A Mad Scientist Twisting Small Block Ford Dr. Setzer

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.

RootsThe 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 31/48-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 11/416-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 FirstWith 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."

CamologyAfter 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 RamTo 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.

Dyno DaysWith the final assembly completed, Tom entered what the boys at Westech call "The Polygraph Room" where he bolted the 306 to Westech's SF-901 dyno. The power quest began with a Victor Jr. intake and a 750-cfm Demon carburetor, but that was just to ensure the engine made acceptable power. Next, Tom bolted on his fabricated intake and eight-coil ignition with the FAST controller and set to tuning fuel and spark.

Once Tom had the engine fine-tuned, he uncovered some interesting personality traits. To no one's surprise, the engine was very peaky: utmost horsepower occurs at a stratospheric 7,100 while max torque hovers around 6,200. Not only that, but the engine clearly prefered larger 131/44-inch headers over the smaller, chassis-friendly 151/48-inch versions. The bigger headers made 10 more numbers everywhere in the curve, so it's a shame they won't fit in the car.

Oil's Not WellAfter his first set of dyno flogs, Tom discovered several distressed rod and main bearings. This predicated the addition of a Manley high-volume oil pump and an ARP pump shaft to improve oil flow to the rotating assembly. A stronger oil-pump shaft is critical since small-block Fords are famous for twisting them in two, even on mild small-blocks. A subsequent teardown indicated that even this didn't solve the problem. Tom next added an SVO engine oil restrictor kit and tossed the factory Ford hydraulic rollers in favor of a set of Comp mechanical rollers: "I didn't even want to play the game of seeing how much oil I could restrict with hydraulic lifters." It seems the hydraulic rollers pump much more oil to the top end, starving the rest of the engine. This is mainly due to the fact that the little Windsors are designed to direct oil through the lifters first, then down to the mains and rods. "I wore it out twice before we got that figured out," Tom said.

Rule Number 7 in The Great Book of Camshafts will tell you not to run solid-roller lifters on a hydraulic-roller cam. The fundamental difference comes down to a lack of clearance ramps on the hydraulic-roller cam. Clearance ramps are a gentler lifter rise built into a mechanical-lifter lobe that closes up the 0.018 to 0.020 inch of lash built into all solid lifter camshafts. Tom meditated with his cam guru and dialed in 0.004 inch of hot lash into his valvetrain and has yet to have a problem. But maybe that's because Tom likes living on the edge. "It's definitely noisy. But the purpose of this car is to be noisy and pissed off."

Let The Beatings ContinueSo far we've covered the buildup and dyno sessions. By the time Tom bolted the motor in the car and got as close as low 10s with an automatic, he realized it was time for a manual gearbox. At that point, Tom says, "I had over 80 recorded engine dyno pulls and well over 180 runs altogether on both the engine and chassis dyno, not counting the runs down the dragstrip. That's pretty sick when you think about it!"

There's as much of a story on Tom's trials with traction and pulling off his 10-second dream as the engine buildup, so we'll save all the good drivetrain stuff for next month. Until then, mull over how much those stock cast main caps are moving around at 500 hp at 7,100 rpm!

'Dyno TimeTest 1: The 306ci small-block with 151/48-inch chassis headers and 91-octane pump gas.

Test 2: Same configuration with 131/44-inch headers and VP Ultimate 4 motorcycle race gas that is highly oxygenated. The headers alone made about a 32hp peak increase, while rest of the gains are from the fuel. This is one of Tom's power secrets, and we plan to investigate more on that later.

  TEST 1 TEST 2 DIFFERENCE
RPM TQ HP TQ HP TQ HP
4,600 352 308 382 335 +30 +27
4,800 365 334 389 356 +24 +22
5,000 375 357 391 373 +16 +16
5,200 375 371 393 389 +18 +18
5,400 376 387 394 406 +18 +19
5,600 380 405 398 424 +18 +19
5,800 376 416 396 438 +20 +22
6,000 375 428 399 456 +24 +28
6,200 375 442 401 473 +26 +31
6,400 371 452 401 489 +30 +37
6,600 364 458 396 498 +32 +40
6,800 358 464 391 507 +33 +43
7,000 353 470 382 510 +29 +40
7,200 342 469 372 510 +30 +41
7,400 332 469 353 498 +21 +29
Peak 378 472 403 512    
Power/ci 1.23 1.54 1.31 1.67    

'AFR 185 cNC Windsor Ford Flow TestThese are the flow numbers on the Westech bench using Tom's heads that are angle milled to 51cc chambers. This is with his 2.20/1.60-inch valves and valve job on a 4.030-inch bore with a radiused entry on the intake side and no flow tube on the exhaust side.

VALVE INTAKE EXHAUST E/I
LIFT      
0.050 32 24 75%
0.100 67 56 84%
0.200 145 114 79%
0.300 202 155 77%
0.400 230 174 76%
0.500 248 183 74%
0.600 265 185 70%
0.700 272 188 69%

E/I represents the flow relationship in percentage of the exhaust port to the intake port. Generally, percentages over 70 to 75 percent are considered good.

SOURCES
COMP Cams Milodon
2250 Agate Ct.
Simi Valley
CA  93065
805-577-5950
www.milodon.net
Airflow Research (AFR)
Pacoima
CA
airflowresearch.com
Sportsman Racing Pistons (SRP)
7-14/-898-9763
www.jepistons.com
MSD Ignition
El Paso
TX
9-15/-857-5200
msdignition.com
Automotive Racing Products (ARP)
531 Spectrum Circle
Oxnard
CA  93030
805-278-7223
Westech Performance Group
11098 Venture Dr., Unit C
Mira Loma
CA  91752
9-09/-685-4767
www.westechperformance.com
Scat Enterprises
3-10/-370-5501
scatenterprises.com
Fuel Air Spark Technology (FAST)
Ashland
MS
www.fuelairspark.com
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