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Small Block Chevy Intake, Carb, Camshaft Testing - Danger Mouse Part 4

New Manifold Gives A Big Boost

By Mike Petralia

CLICK BELOW TO SEE ALL OF THE STORIES COVERING THE BUILD OF PROJECT DANGER MOUSE

DANGER MOUSE PART 1

DANGER MOUSE PART 3

DANGER MOUSE PART 4

DANGER MOUSE PART 5

DANGER MOUSE PART 7

DANGER MOUSE PART 8

DANGER MOUSE PART 9

DANGER MOUSE PART 10

DANGER MOUSE PART 13

DANGER MOUSE PART 14

DANGER MOUSE PART 15

DANGER MOUSE PART 18

DANGER MOUSE PART 20

DANGER MOUSE PART 22

DANGER MOUSE PART 23

DANGER MOUSE PART 24

DANGER MOUSE PART 25

A New Intake, Cam, Carburetor, And Spacer
When we started out building Danger Mouse (DM), we knew that testing it would probably turn out to be the most fun we've had on the dyno in a long time. We were correct. For DM's third test we took the same approach most low-buck hot rodders would in the early stages of searching for the most power for the least dollars. We thought a different intake manifold and carb, along with maybe a new carb spacer and a bigger cam, would be the way to go. The results were outstanding, particularly from the new Edelbrock Performer RPM "Air Gap" intake manifold (PN 7501, $195.95 from Summit Racing) we installed.

The decision to retire the Weiand Action Plus intake manifold we had been running since the original dyno tests was not an easy one. However, our search for a new manifold with a larger intake plenum, and one that would also keep the intake charge cooler, revealed only one candidate. Edelbrock had just what the Doctor ordered in its new "Air Gap" design. With its larger plenum area raised up off the floor of the intake, the Air Gap RPM breathes better while keeping hot oil off the bottom of the plenum, which adds unwanted heat to the fresh incoming charge.

This is not to say that the Weiand manifold was flawed in any fashion. In fact, it made terrific power for its extremely affordable, under $100, price tag (currently $99.95 from Summit Racing), and it boosted our baseline power figures by 17 hp. For a first-timer on a low budget, the Weiand 8004 intake manifold is still a great buy.

Power Recap
Last month in DM's second bash on the dyno, we ended the day with a maximum 356 hp and 413 lb-ft of torque. The average horsepower and torque figures were 292 and 395, respectively (see: Test 8). That was 7 hp and 8 lb-ft more torque than we'd started the day with, not that impressive if you're just looking at peak numbers. However, low-end power was increased with the addition of a new cam last month, but we knew we could do better, even with the stock heads still in place.

So this month we first tried a new Speed Demon double-pumper carb, bolted on the new Edelbrock intake manifold, put a Wilson 1-inch open spacer between the carb and intake, and finally installed the next size larger COMP Cams Xtreme Energy camshaft to see what it'd do. The reward this month was a new max 386 hp and 438 lb-ft of torque (+30 hp and +25 lb-ft), and the new averages were 316 hp/416 lb-ft (+23/+20). Now we've got this 355-cid, stock-headed iron Mouse making almost 390 hp and 440 lb-ft of torque. So far this looks like the best formula for power with the stock heads, particularly since the motor didn't respond too well to the bigger cam.

That means that the cylinder head's flow potential is just about maxed out, and we'd either have to go in and start porting or install a new set of performance cylinder heads. We think we'll take the latter option, since it'll probably produce results that you could duplicate in your engine. Keep sending your suggestions in and we'll begin tackling them in the upcoming months.

Test 9: Speed Demon 750 Double-Pumper Carb
Since we were planning an intake manifold test for the next round and the Air Gap intake won't accept a Q-jet carb, we needed to test with a square-flange carb first so we'd see exactly how much the carb or intake would add on its own. Westech had a 750-cfm Demon carb that we borrowed for this test. It worked best with 82/88 jetting. Torque improved a little in the lower-rpm ranges compared to the Q-jet, which surprised us. Peak horsepower didn't increase at all, but peak torque figures increased by 5 lb-ft.

Test 10: Edelbrock Performer Rpm "Air Gap" Manifold
We also "borrowed" this Edelbrock Performer RPM Air Gap (PN 7501) manifold from Westech to see if its larger plenum volume would improve power, even though the engine still had the stock heads and a small cam. It worked fantastically, giving us the largest single power increase of any part so far with 24 more peak ponies and 20 more lb-ft of torque.

Test 11: Wilson 1 1/4-Inch Open Spacer
Westech told us they've often seen improvements by adding a 1 1/4-inch open carb spacer (PN 000020) to the Air Gap manifold, so we thought we'd give it a try. Our results were not great, and power actually fell off just about everywhere. That probably means that the Air Gap's plenum was large enough for DM, and it didn't need the extra volume a 1-inch spacer added.

Test 12: Comp Cams Xe262h Cam
To either prove or disprove our theory on whether or not the engine needed more air to make more power we swapped in the next size larger COMP Cams XE262H Xtreme Energy camshaft (PN 12-238-2). The cam was 6 degrees bigger at 0.050 with 0.015-inch more lift and added a little more top-end power while giving away some low-end grunt. It was kind of a wash, but we think the motor liked the XE256H cam better, and it would definitely have driven better on the street with the extra low-end power of the 256 cam. However, since we plan to test new heads next month, we'll leave the 262 cam in place because it'll probably respond well to the better-breathing heads.

3rd Series Of Dyno Tests
We number each series of tests consecutively, starting with the number after the last of the previous month's tests. We'll also list the last test from the previous month, so you'll have something to compare the new tests to. So this month our first new test is number 9. Unless listed, no other changes were made for any test.

Test 8: Last test from last month. Weiand 8004 intake, COMP Cams 1.5:1 full-roller aluminum rockers, Carb Shop Q-jet, COMP Cams XE256H cam (256/268 adv duration, 212/218 duration @ .050, .447/.454 valve lift, 110 lobe separation, installed 2 degrees advanced), 1 3/4-inch Hooker Super Comp headers and Flowmaster 3 1/2-inch mufflers, 37 degrees total advance.

Test 9: Install Speed Demon 750 carb with 82/88 jets.

Test 10: Install Edelbrock Performer RPM "Air Gap" intake manifold.

Test 11: Install Wilson 1 1/4-inch-tall open aluminum carb spacer.

Test 12: Install COMP Cams XE262H cam (262/270 adv duration, 218/224 duration @ .050, .462/.469 valve lift, 110 lobe separation) straight up.

  Test 8 Test 9 Test 10 T10 Test 11 Test 12
RPM TQ HP TQ HP TQ HP HP TQ HP TQ HP
2600 384 190 393 194 411 203 +7 403 200 396 196
2800 386 206 395 211 413 220 +9 408 218 404 215
3000 398 227 403 230 420 240 +10 420 240 416 237
3200 408 249 413 252 430 262 +10 428 261 429 261
3400 410 265 416 269 436 282 +13 427 276 429 278
3600 411 281 415 284 438 300 +16 432 296 435 298
3800 413 299 416 301 437 316 +15 436 315 437 316
4000 410 312 414 315 437 333 +18 437 332 438 334
4200 407 325 408 327 435 348 +21 430 344 436 348
4400 402 337 402 337 429 359 +22 426 357 432 362
4600 394 345 394 345 421 369 +24 420 368 424 371
4800 384 351 386 352 411 376 +24 412 376 417 381
5000 373 355 373 356 398 379 +23 399 379 405 386
5200 358 355 359 355 380 376 +21 384 380 389 385
5400 345 355 346 356 365 375 +19 367 377 375 386
5600 331 353 331 353 347 370 +17 351 374 360 384
Max 413 356 418 356 438 380 +24 437 381 438 386
Avg 395 292 398 294 416 315 +21 414 314 416 316

Send your test suggestions to:
Super Chevy Magazine
Attn: Danger Mouse
720 Hundley Way
Placentia, CA 92870
Or Email: mikepe@mcmullenargus.com

SOURCES
Carb Shop
Ontario
CA
9-09/-947-3575
customcarbs.com
Mr. Gasket Company
10601 Memphis Ave., #12
Cleveland
OH  44144
216-688-8300
www.mr-gasket.com
COMP Cams Summit Racing Equipment
P.O. Box 909
Akron
OH  44309
Demon Carburetion
Dahlonega
Ge
7-06/-864-8544
barrygrant.com
Westech Performance Group
11098 Venture Dr., Unit C
Mira Loma
CA  91752
9-09/-685-4767
www.westechperformance.com
Edelbrock
Dept. 5.0
2700 California St.
Torrance
CA  90503
310-781-2222
www.edelbrock.com
Wilson Manifolds
4700 NE 11th Ave.
Ft. Lauderdale
FL  33334
954-771-6216
www.wilsonmanifolds.com
Fluidampr
Springville
NY
7-16/-592-1000
fluidampr.com
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By Mike Petralia
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