TCCoA Forums banner

1 - 3 of 3 Posts

·
Registered
Joined
·
184 Posts
Discussion Starter #1
Hi guys,
I did a bit of searching but found no answers. Do cams have any effect on emissions and do you think that I will still pass CA smog requirements with Comp Cams in NPI heads??
 

·
Sheepish
Joined
·
4,085 Posts
Depends on how hairy the cams are, and how good the tuner is. If the tuner can keep it from being too noticeable (IE not able to smoke a pack between lopes) and you can still pass a sniffer you should be fine. I doubt they'll pull your cam covers to check the cams, but after what they did to Lonnie, I wouldn't put it past em.
 

·
Registered
Joined
·
3,178 Posts
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? :)
 
1 - 3 of 3 Posts
Top