High Altitude Clutching & Jetting Viper

Homer

Homer

New member
Joined
Sep 10, 2006
Messages
40
Age
56
Location
Minnesota
Hi Guys.

In March I am going to drag the Viper short track out West for one of my buddies that doesn't have a sled. Could someone post the jetting and clutching specs for a stock viper for 8000 to 12000' elevation? please post the MJ, NJ, JN, PJ and the fuel screw settings if possible.

Thanks
 
8300' - 10,000' at 0 degrees F
MJ= 143.8
PJ= #55
JN= 2.5
PS =3-1/8 turns

Clutching
8EK 13.3 steel inner, empty outer hole
Y-W-Y spring
secondary
red spring at 70 degree twist, ( I would use a green sec spring at that elevation at 70- 80 twist)
gearing 20-38
 
Thanks for the info!

The only thing I think you left out was the needle jet. If you have that as well, that would be great.

Thanks
 
I assume when he put JN 2.5, that would be the 2 1/2 clip position. The needle jet should be like P-8 or Q-0. Please help!

Thanks
 
The stock needle jet (the brass tube the needle rides in) is a P8. Are you saying it does not need to be changed from stock for High Altitude?
 
The jetting chart in my service manual dosn't show a different jet needle for high altitude.
I have ran mine in the # 2 or 1.5 position before, depending on temps. This is at 6500' to 8000'. I would set it to 2.5 (spec) and check the plugs. If required the needle can be adjusted from there, faily easy.
You'll notice the pilot and fuel screws are at a richer setting then at sea level. This is because the thinner air density dosn't draw fuel through the smaller orifices as well. Thus requiring a larger hole (pilot jet). The same is true for the needle setting some what. At larger throttle openings the velocity overcomes the thinner air issue, and requires smaller main jets.
The needle setting is that cross over area. So sometimes an adjustment of the needle is required (usually leaner) when you get to the mountains. Just have to try it and see how she runs. Air density changes from one mountain range to another, and weather (baro pressure) is a big factor also.
 
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