[chunky`]

But who has the solution? Chunky does.

Watch the video, and please read this entire thread.
http://www.youtube.com/watch?v=KdWk-CCKfuU

I have a very good idea of what is causing timing chain failures with skunk2 cams now. Let's see if someone can guess what the problem is.

Some notes about the video:

1) I just installed a BRAND NEW timing chain tensioner. It was modified with my dual spring setup.

2) The head is freshly rebuilt and a new tensioner was put in at that time. I was replacing a tensioner that was barely 300 miles old. That is how fast I've been burning through tensioners on my car.

3) The exhaust cam is degreed in to the 107 centerline as specified by Skunk2.

Here is a dyno of the skunk2 cams before & after the exhaust cam gear. I also installed a mildly ported head duing this rebuild. Note that the blue line is untuned.

Top end power was a little down (the spike to 228 barely counts), but I'm sure I can eek out more power. As skunk2 said, there is a LOT more midrange power with the exhaust cam gear dialed back. I moved my VTEC down to 5250 after the dyno session. I could go even lower to be honest. I won't know until I hit the dyno again. I'm sure the ported head had some impact. I can't wait to see the final dyno numbers

Now, as for what is causing the chain slap? Why are skunk2 cams having problems with tensioners? I finally have a relatively clear picture of what's happening. I also have a potential solution. That's right folks, 3 rebuilt heads and numerous tensioners later, I think I know how to counteract the tensioner issues so I can possibly start daily driving my car again. Most people would have given up 2 rebuilds ago. For some strange reason, I kept going; I can't just "give up." It's nice to finally feel like I've made progress. My 2007 was defined by this problem. I'm just glad I can (hopefully) move on now. =)

 

[bossman032]

wow.

its look like it jumping is the tension unit going back an forth because of the chain being to slack?

when I installed the vtc unit on the tsx I didn't see this problem..looks like an error on skunk2 part?

whats causing it to do that..?

 

[chameleon]

so your saying, the actual retarding the exhaust gear aligns the cams to a point where one side closes and the intake opens it gives the chain a bit of slap to cause a snap pull on the chain... and this is strong enough of an impact to shred the locking teeth and the locking pin on the tensioner?

honestly i dont remember having that same scenario. but please share more details with us.

 

[signalpuke]

Our F20C has the same slap sound from the S2 cams.

 

[McCoy]

I would like to see a follow up video of the same after you make solution work. A lot of folks running hotter cams are experiencing tensioner failure as you are aware of. Thanks for posting!!

 

[JustinD]

i installed a set of Skunk2 stage 2 cams in a friends motor and the chain was doing that exact same thing after we were done and we were rotating the motor.

i didnt like, but i had never seen it before with my IPS cams.

the guy called skunk2 and they said it was most likely the valvesprings causing it ? wtf.

subsequently, the motor blew up a short time later.

 

[poison]

What do you believe is the possible solution?

I'm gonna have to check my own motor out. Just threw cams in the other day.

 

[onefstek]

I belive that the problem lies with how fast the intake cam lobe goes over center comparing to the exhaust cam.

I can see it in my head but I can't explain it verry well.

 

[NJslvrtypes]

I was saying this in the other thread that my motor was doing this when you turned it over slow.... everybody with skunk2 cams was saying they don't have that issue.

but def interested in your solution as my tensioner and valvesprings are on their way to skunk2 for them to analyze.

tony has been very helpful so far w/ the situation i might add.:up:

 

[H2nr]

was a brand new chain used for this test?

 

[kb58]

Okay, the chain's being pulled CW, so the right-hand gear is the only thing powering this little demo video. The left-hand pulley is only trailing along behind, pulled by the chain. However, for slack to occur means that the left-hand gear is moving forward on its own, catching up with the right-hand pulley, hence the slack. The only way that can happen is if the combination of cam ramp angles, lob indexing, and high spring pressure, are pushing the cam foward. Think of it like squeezing a marble (the cam lob) between your oily fingers (the springs). At some point the marble's going to get squeezed out from between your fingers and accelerated forward.

Do I win a cookie?

 

[onefstek]

Okay, the chain's being pulled CW, so the right-hand gear is the only thing powering this little demo video. The left-hand pulley is only trailing along behind, pulled by the chain. However, for slack to occur means that the left-hand gear is moving forward on its own, catching up with the right-hand pulley, hence the slack. The only way that can happen is if the combination of cam ramp angles, lob indexing, and high spring pressure, are pushing the cam foward. Think of it like squeezing a marble (the cam lob) between your oily fingers (the springs). At some point the marble's going to get squeezed out from between your fingers and accelerated forward.

Do I win a cookie?

Way better job at describing then what I attempted. Good job.

 

[poorg]

Okay, the chain's being pulled CW, so the right-hand gear is the only thing powering this little demo video. The left-hand pulley is only trailing along behind, pulled by the chain. However, for slack to occur means that the left-hand gear is moving forward on its own, catching up with the right-hand pulley, hence the slack. The only way that can happen is if the combination of cam ramp angles, lob indexing, and high spring pressure, are pushing the cam foward. Think of it like squeezing a marble (the cam lob) between your oily fingers (the springs). At some point the marble's going to get squeezed out from between your fingers and accelerated forward.

Do I win a cookie?

My thoughts exactly !!!

 

[KON]

Very interested to see a permanent solution. I have the skunk2 stage 2's in my K20a2 head with the pro series valve springs and the toda ct. So far, I've put close to 5000 miles on the setup with no problems (as far as the tensioner is concerned) and the timing has never skiped teeth (I check regularly). Motor runs strong and no sign of problems yet.

 

[nikos]

Kon, are you running an exhaust cam gear?

 

[KON]

Kon, are you running an exhaust cam gear?

Yes, its set at -3 marks. Nikos, nice numbers on the k25...gatta love the tq.

 

[JDM96SpecCTR]

is it me, or are all the timing chain/tensioner issues on k24's only?

 

[KON]

is it me, or are all the timing chain/tensioner issues on k24's only?

I disagree...I see it to be a more frequent issue with the high revving K20's more so then the K24's. I have a K24 bottom end with a K20 head and no problems while many others who post about experiencing this problem have K20's.

 

[signalpuke]

Chunky, what are you using to turn the motor over in the video? By hand?
JDM96SpecCTR, displacement has nothing to do with this issue, it is all in the valve train.

 

[DonF]

To do an apples to apples comparison i would like to see Crower, IPS, and Jeff,s cams turned over by hand. That could help with opening abd closing ramps.