All the talk about Cams

[RSNAKE]

I hear a lot of folks talk about year X cam is better that than year Y cam and so on and so on. I would like to get the record straight. Is the chart on this board correct or not?

http://www.viperclub.org/menus/index_ivr.htm

If it is correct then everything about all GEN II cams is the same except:

1. The 1998-2002 cars have .001 inches more intake and exhaust valve lift
2. The 2000-2002 cars have 6 degrees less valve overlap

In cam lift terms .001 inch lift is insignificant. I would think that this is probably a typo. In any case, this means that all GENII cams have nearly identical (if not completely identical) duration and lift numbers. The only difference is in the overlap.

Is this true?

 

[KenH]

Your correct. The lift and duration have stayed about the same, but the older cam had 6 degrees of additional overlap which gave it a lumpier idle.

As I understand it, the increased overlap allows for better scavenging on the exhaust stroke and provides more power, but poorer emissions. Perhaps accounts for part of why the older cars respond better to exhaust mods. There was also a lifter change around the same time which also contributed to the smoother idle I believe.

--- Ken

 

[Daffy Duck Viper]

At first I was wondering if that cam was also a contributing factor that prevented the Viper from being U.S. 50 state emissions certified smog legal until the 2000 model year. However, upon checking the chart, that same cam was being used in 1999 when the Vipers became U.S. 50 state emissions certified smog legal. So, what change brought about this since it wasn't the cam? Anyone know?

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