Combos 1-3 came from the World Products web site. Although only cam duration numbers are given, all of the three different duration numbers happen to be the exact durations of the three most popular Comp Cams Xtreme Energy camshafts.

Combo 1 is a basic engine build with the popular Sportsman II heads and a conservative camshaft. Although torque numbers are not given, the short-duration cam probably helps to produce more than 350 ft-lbs of torque.

Combo 2 has a little more compression, which could account for a little bit of power gain, but the cam with longer duration is what really raises the power. I am sure that the torque does not increase too much, and it may actually decrease. The carb upgrade might have added power, but the 600 cfm carb could have easily produced this much power.

Combo 3 has even more compression than the previous combos, which probably adds some power. The combustion chambers are cleaned up some, and an even more aggressive cam is used on this engine. If the camshaft is the Xtreme Energy grind, the torque is beginning to have some trouble with this amount of duration.

Combos 4-7 comes from page 39 of the February 1989 issue of Hot Rod Magazine. All four combos use the 383 cu. in. engine with rebuilt GM heads and Holley 750 double pumper. These combos show the difference between some intakes and heads.

Combo 4 uses an Edelbrock Performer intake and a 280� cam. The power and torque numbers are pretty good.

Combo 5 keeps the Performer intake from Combo 4, but a 292� cam is used. This camshaft duration increase drives the power up 17 HP, and the torque stays about the same. It is suprising that a cam with this much duration does not drop the torque level.

Combo 6 goes back to the 280� camshaft, but an Edelbrock Victor Jr. intake is used instead. This combination produces 17 more HP and a little more torque. Even though the Victor Jr. intake has been billed a high-RPM-only intake, this comparison shows that the intake produced more low-end torque than the Performer. Victor Jr.'s are becoming popular intakes as more car guys realize just how streetable they are.

Combo 7 uses the Victor Jr. intake with the longer duration cam. The result is over 420 HP and a torque level still over 400 ft-lbs.

Combos 8-10 come from the Trick Flow Specialties web site. All three combinations use the same 383 cu. in. engine with a moderate roller camshaft and 10:1 compression. The next three combos vary cylinder heads.

Combo 8 uses the Trick Flow 23� Street heads. These heads are not the Twisted Wedge heads for which Trick Flow became known. Instead, these are direct bolt-on heads, and are marketed to compete with $750/pair to $1,000/pair heads such as the World Products Sportsman II, Dart Iron Eagle, Edelbrock Performer RPM, Holley Systemax, etc. With some help from the roller cam, this engine makes 460 HP and 451 ft-lbs of torque.