Test 7: A COMP Cams XE256H cam (256/268 adv duration, 212/218 duration @ .050, .447/.454 valve lift, 110 lobe separation) was swapped in, 2 degrees advanced, and we were rewarded with lots of grunt (compare Tests 6 & 7).Max 413 tq, 357 hpAvg 396 tq, 293 hp
Test 8: This was our very first weird test. We witnessed that the 3/8-inch screw-in studs in the heads were flexing as we lashed the valves, so we hypothesized that it might kill some lift and duration. In an attempt to prove our hypothesis correct, we installed a COMP Cams stud girdle. Power and torque fell off at most rpm, so the stud girdle was later removed.Max 413 tq, 356 hpAvg 395 tq, 292 hp
Note how DM's powerband slowly increases as we keep trying different parts.
Tests 9-12: Bigger carb, "Air Gap" manifold, new carb spacer, bigger XE262H cam (December 2002).
Test 8 ended the day with a maximum 356 hp and 413 lb-ft of torque, and average figures were 292 hp and 395 lb-ft. This month we tried a new Speed Demon carb and an Edelbrock Performer RPM "Air Gap" manifold with a Wilson 1 1/4-inch open spacer. We also installed the next-size-larger COMP Cams Xtreme Energy camshaft. The final reward was a new max 386 hp and 438 lb-ft of torque, and the new averages were 316 hp/416 tq. Now we've got this stock iron-headed 355-cid Mouse making almost 390 hp and 440 lb-ft of torque! So far this looks like the best power formula with the stock heads, particularly since the motor didn't respond that well to the bigger cam. That means that we just about maxed out the stock cylinder head's flow potential and would either have to go in and start porting or install a new set of performance cylinder heads for more power.
Test 9: Installed Speed Demon 750 carb with 82/88 jets.Max 418 tq, 356 hpAvg 398 tq, 294 hp