For smog-related things, you need a cam with a short overlap.
To find overlap, we'll use a randomly numbered cam:
say its 224/236 duration on a 112 LSA. This isn't an unusual kind of spec to see.
Add the 2 duration numbers together: 460.
Divide by 4: 115. Why? First you'd divide by 2 because you want the average. The second division by 2 is because duration is measured in CRANK degrees, not CAM degrees.
Okay, now take the 115 and subtract your 112 LSA: 3.
3 converted back to CRANK degrees is 6 degrees of overlap.
The higher the overlap, the more of a chance there is that unburned fuel/air will go straight into the exhaust. In the case of smog nazi's, this is to be minimized. Stock cams have NO overlap, actually they have a large spot where no valve is open. This leaves a lot to be gained by cams.
Based on looking at the Comp page, I'd say the 102100, 102200, and 102500s look okay... where's goldbird when you need him to show how his 102200s are working out?
96 Mustang GT 5spd. w/ 248A Option (GTS). Stock for now until I get the Roush on.
97 Thunderbird 4.6L LX /w Sport Package
24k B&M Cooler, 1" lowered, Steeda UD Pulleys, Dynomax cat-back, J-mod, 3.73's, PI intake, PI cams, 03 GT MAF/Tube, SCT tuned - Gone but not forgotten.
MAMN12 Drag Racing Team [email protected]
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