can someone explain coil bind?
06-24-2009, 02:01 PM
#1
2nd Gear Member
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Join Date: Oct 2008
Location: massachussets
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can someone explain coil bind?
exactly what the title says. i'm about to buy some cams, but i want a higher lift cam than companies offer for npi heads. so i'm looking at pi cams. i just want to understand all the cam bullSh*i before i go ahead and purchase. i asked 10inchterror (cms) about his stage one cam and he said that i would need springs and offset retainers for his cams to work. well i'm running pi cams with pi springs already so why would i need new springs when the cam advertises no aftermarket springs needed and why would i need offset retainers. sorry if this is a retarted question i'm just trying to understand everything
06-24-2009, 04:05 PM
#2
TECH SAVANT
Join Date: Dec 2006
Location: Saint Augustine, FL
Posts: 10,938
"Coil bind" happens when the lift of the cam, multiplied by the lift ratio of the followers, is so much that the valve spring fully compresses before maximum lift happens.
It is always bad, even if just a little bit, and to extremes it is VERY bad and will break something probably the follower, or timing chain.
Coil binding can also happen in coil spring suspensions, if the spring rate is insufficient and/or the shocks are too wimpy...
It is always bad, even if just a little bit, and to extremes it is VERY bad and will break something probably the follower, or timing chain.
Coil binding can also happen in coil spring suspensions, if the spring rate is insufficient and/or the shocks are too wimpy...
06-25-2009, 09:09 AM
#3
3rd Gear Member
Join Date: Jan 2009
Location: Florida
Posts: 570
exactly what the title says. i'm about to buy some cams, but i want a higher lift cam than companies offer for npi heads. so i'm looking at pi cams. i just want to understand all the cam bullSh*i before i go ahead and purchase. i asked 10inchterror (cms) about his stage one cam and he said that i would need springs and offset retainers for his cams to work. well i'm running pi cams with pi springs already so why would i need new springs when the cam advertises no aftermarket springs needed and why would i need offset retainers. sorry if this is a retarted question i'm just trying to understand everything
The stock retainer hits the valve seal at 0.540" lift on a NPI head.
Bullet now has both a Stage 1 and a Stage 2 cam that will work in those NPI heads without changing valve springs or retainers.
06-25-2009, 05:01 PM
#4
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ooo i c. i was trying to find the specs on the npi valve train and couldn't find anything so i was confused why stock pi cams work fine but aftermarket one wouldn't. now the whole coil bind thing makes sense. thanks for the responses guys real helpful!!
now for the bullet cams. where can i find them to compare them to other companies price and performance wise?
now for the bullet cams. where can i find them to compare them to other companies price and performance wise?
06-26-2009, 08:12 AM
#7
3rd Gear Member
Join Date: Jan 2009
Location: Florida
Posts: 570
ooo i c. i was trying to find the specs on the npi valve train and couldn't find anything so i was confused why stock pi cams work fine but aftermarket one wouldn't. now the whole coil bind thing makes sense. thanks for the responses guys real helpful!!
now for the bullet cams. where can i find them to compare them to other companies price and performance wise?
now for the bullet cams. where can i find them to compare them to other companies price and performance wise?
Bullet cams
06-26-2009, 08:13 AM
#8
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07-01-2009, 09:56 AM
#9
2nd Gear Member
Thread Starter
Join Date: Oct 2008
Location: massachussets
Posts: 467
can somebody explain to me the concept of duration. i know what it means but i don't know what the numbers mean. its the amount of time that both the intake and exhaust valves are open to create scaveging. great lol. but what do the numbers mean for example the bullet stage one cam duration specs (215/218 at .050 lift) what the heck does that mean. i know the numbers are measuring degrees in crank rotation but how does that relate to duration. enlighten me
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