We've often joked in these pages that the words budget built and Mopar Stroker can never be uttered in the same sentence. At least that's what we used to think.
Two months ago, we did a theoretical build of an LA engine using a 318 as the foundation. We cheekily referred to it as an almost-500hp engine you could build for a little more than $5,000. Well, we decided to take up our own challenge and assemble that small block Mopar Stroker. With the help of Brian Hafliger of IMM Engines in Indio, California, we killed our horsepower goal, but we also overshot our budget by a similar percentage. Nevertheless, we still think of this as a good build. Chrysler guys, put this in your Duster and drive it.
Mopar Stroker
CYLINDER HEAD FLOW
BARE HEADS
WITH RPM
WITH SUPER VICTOR
LIFT
INTAKE
EXHAUST
INTAKE
INTAKE
0.100
69
58
69
69
0.200
141
119
139
140
0.300
197
161
185
190
0.400
241
184
215
227
0.500
267
193
230
242
0.550
271
195
233
245
Baseline
Start saving money for tires now. This thing is a torque monster.
Components: Edelbrock RPM Air-Gap dual-plane; Holley 750 carb with 71 primary jets, 80 secondary jets; TTI 15/8-inch stepped headers; 34 degrees total timing; 155-degree water temperature; 160-degree oil temperature.
RPM HP LB-FT 3,000 256 449 3,200 281 461 3,400 303 468 3,600 327 478 3,800 354 489 4,000 382 502 4,200 402 503 4,400 422 504 4,600 439 502 4,800 449 491 5,000 454 477 5,200 469 474 5,400 474 461 5,600 473 444 5,800 474 430 6,000 474 415
Test 1: Best Run
Adding a 1-inch open spacer and jetting up the carburetor produced the best numbers we'd see out of this engine.
Components: same as baseline plus a 1-inch open carb spacer and a jet change to 73/84.
RPM HP LB-FT 3,000 255 446 3,200 276 453 3,400 294 455 3,600 321 469 3,800 354 489 4,000 383 504 4,200 409 512 4,400 432 517 4,600 450 514 4,800 461 505 5,000 467 490 5,200 479 484 5,400 485 471 5,600 483 453 5,800 478 433 6,000 472 413
Test 2
Next, we tried bigger headers but didn't gain any power.
Components: same as Test 1 but substituting larger Hooker Super Competition 13/4-inch headers.
RPM HP LB-FT 3,000 246 430 3,200 268 440 3,400 295 456 3,600 323 471 3,800 352 487 4,000 381 500 4,200 409 511 4,400 431 514 4,600 448 512 4,800 458 502 5,000 465 488 5,200 477 482 5,400 482 469 5,600 482 452 5,800 477 432 6,000 470 412
Test 3
We tried even bigger headers, but power was down slightly.
Components: same as Test 1 but with TTI 1 7/8-inch headers.
RPM HP LB-FT 3,000 254 445 3,200 273 449 3,400 291 449 3,600 318 464 3,800 350 483 4,000 380 499 4,200 406 508 4,400 429 512 4,600 445 508 4,800 457 500 5,000 462 485 5,200 477 481 5,400 483 470 5,600 482 452 5,800 478 433 6,000 471 412
Note: Removing the spacer dropped power substantially-minus 30 lb-ft off peak.
Test 4
We went even bigger with the manifold, and the engine liked it even less.
Components: Edlebrock Super Victor intake; Holley 750 carb with 74 primary jets, 83 secondary jets; TTI 1 7/8-inch headers; 1-inch open spacer; 34 degrees total timing; 150-degree water temperature; 165-degree oil temperature.
RPM HP LB-FT 3,000 238 417 3,200 255 419 3,400 269 416 3,600 285 415 3,800 311 430 4,000 341 448 4,200 369 461 4,400 395 472 4,600 421 481 4,800 442 483 5,000 455 478 5,200 471 475 5,400 479 466 5,600 480 450 5,800 474 429 6,000 469 411
Test 5
For the last test, we put the smaller headers back on and saw a slight improvement in torque.
Components: same as Test 4 but with TTI 1 5/8 stepped headers.
RPM HP LB-FT 3,000 238 417 3,200 260 427 3,400 279 431 3,600 293 428 3,800 319 440 4,000 352 462 4,200 378 473 4,400 404 482 4,600 430 490 4,800 448 490 5,000 459 482 5,200 472 477 5,400 477 464 5,600 475 446 5,800 472 427 6,000 472 413
More power?
Ultimately, the cylinder heads are the cork in this combination. The intake ports have to neck-down substantially to clear the pushrods. This pushrod pinch limits how much air the engine can ingest. You'll have to step up to more expensive heads to get any more power out of this combination, which we may do in a later article.
We did go over our budget, however. We really wanted this thing to come in at less than $5,500 but overshot our goal by nearly a grand. As you see in the pictures, this engine costs $6,973.48 to build carb to pan. "Small-block Mopars are some of the most expensive engines to build," Hafliger told us after we added up the costs.
However, it would be possible to save a few hundred dollars here and there-noncoated headers, reusing the stock rocker hold-down system, and buying a used carburetor, for example. Shop around and you could probably build a similarly potent engine for $6,000. Either way, we were impressed with this combination. Drop this in a light Valiant or Dart and go 11s.
PARTS LIST Description PN Source Price '74 Dodge 360 long-block N/A Junkyard $150.00 Block prep and machining N/A IMM Engines 450.00 Stroker kit 9-360-4000-6123 IMM Engines 1,600.00 Kit consists of: Scat 9000 series crank 9-360-4000-6123 Scat I-Beam rods 2-ICR6123-7/16 ICON 20.5cc forged pistons IC745 +.040 ICON moly rings 1/16-3/16 ACL bearings Balancing Master gasket kit 95-3343-VR Victor Reinz 120.00 Melling oil pump MEL-M72 Summit 25.95 Melling oil pump drive MEL-IS-72 Summit 39.95 Double roller timing set 08-1103-NC Engine Pro 54.00 Damper PB1004N-NC Engine Pro 89.00 Cams and lifters CL-20-229-4 Comp 195.95 Oil pan: street/strip 7Q MIL-30940 Summit 239.95 Oil pan pickup MIL-18345 Summit 42.95 IMM-prepped LA cylinder heads 20301 IMM Engines 1,395.00 Roller rocker arms HUG1506S-16 Hughes Engines 440.00 Rocker hold-down kit HUG7440 85.00 Pushrods: hardened 5/16-inch HUG-5479 Hughes Engines 172.00 Edelbrock RPM Air-Gap 7576 Edelbrock 259.95 MSD distributor 8534 MSD 198.95 MSD Super Conductor wires 32749 MSD 81.95 Holley 750 double-pumper 0-4779C Holley 434.88 TTI 1 5/8 coated LA headers TTI340A-C4 TTI Exhaust 748.00 Valve covers PC3308 ProComp Motorsport 150.00 1-inch open carburetor spacer 5764 Spectre 33.99 Total $6,887.47
