Carlitos

I have a bad feeling that the 918 springs aren't up to the challenge these new XE-R lobes present. Here's my story:

Recently, I feel like some of the power I had immediately after the cam swap has been missing (esp. low end). I've also been wondering if the valvetrain noise I've been hearing is the normal valvetrain noise expected after a cam, spring and pushrod swap. It's not obnoxiously noisy and until now Ive attributed it to the high lift and fast ramp rates of the cam. Now, I believe the sound to be a (possible) bent pushrod. It sounds kind of like shaking a salt shaker really fast and the sound seems to match pace with the rpms. I will have to try and find the time later this week to verify this. But there's more to the story...

I also just recently AutoTapped my car and got some strange, seemingly (I'm no AT guru) conflicting readings. My LTrims were showing me running way lean (+18-20%) but my O2s were showing me running way rich (.980-.995!) at WOT.

Yet another recent incident I recall was when I was making a run with a TA. I was pulling to the top of 4th and at about 6200 rpms the engine just shut off. I was like WTF? It started right back up and ran fine on the way home. (I won by the way <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> )

Now as far as my revelation goes, I hope I'm wrong, but the pieces kind of fit together. If this is indeed a bent pushrod, I'm taking into consideration that it took a lot to bend it. It's one of CompCams hardened pushrods and it's shorter than stock (7.350").

I have a bad feeling that the incident with my car shutting down was a result of P/V contact due to valve float. That could explain the bent pushrod.

If there was P/V contact, then one or more of my valves may be damaged. That would explain the loss of low end torque because of lack of compression.

If I'm losing compression due to a damaged exhaust valve (the higher of the two lifts), then I am losing my intake charge out into my exhaust. That would explain how I'm getting the lean condition and high O2 readings at the same time.

Again, I have yet to verify this and probably won't have the chance to until later this week. I hope I am totally wrong about this, but it all kind of came to me this evening and it's been bothering me ever since. I think I should also note that CompCams recommends the use of their dual springs and Pro Magnum lifters with their XE-R lobes.

There is only one good thing that may come from this. If I find out that I have damaged valves and I have to pull the heads, some new ported and polished heads are going on baby!!! Hehehe <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />

I hope I didn't scare anyone too much, but I really think I need to get the word out for everyone to be cautious with these new XE-R lobes. They're going to be awesome for performance, but it needs to be done right if it's going to last and I seriously believe we should be using the dual springs if you plan on revving beyond the stock limiter.

Sorry this was so long. I'll try and keep everyone updated as soon as I find something out. Someone please tell me I'm wrong about this. No...wait <talking to self> port and polished heads </talking to self> someone tell me I'm right! Doh!!! <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> Someone tell me something!!!

'Los

<small>[ March 25, 2002, 01:23 AM: Message edited by: Carlitos ]</small>

Carlitos

Forgot to add sig...
<img border="0" alt="[Chevrolet]" title="" src="graemlins/camaro.gif" />

VINCE

iTrader: (1)

I think Comp recommended dual springs..

Tin Indian

Carlitos... [Quote] "It's one of CompCams hardened pushrods and it's shorter than stock (7.350")[End Quote]

Here is my opinion (for what its worth)

I first noticed that you dont show any head work in your sig. That would tell me that your heads have not been milled. Thats at least good as far as this discussion goes because at least your heads have not made a change to your lifter preload. That leaves just the cam.

I will bet that the XE-R cam you installed has a smaller base circle than the stock cam it replaced. This is usually the case with very high lift cams. And you have a very high lift cam.

Anyway, when installing a cam with a smaller base circle, it is nesessary to install [longer] pushrods if you want to retain the same lifter preload as before. You installed .050" (50 thousands) shorter pushrods. I would bet that you have none or next to no lifter preload. This probably explains alot of your valvetrain noise. Without lifter preload, you are going to get alot of slop in your entire valvetrain and induce lots of harmonics. And a loss of power, loss of cylinder filling, etc

I would call Comp Cams and ask them what your cams base circle is.

Good luck,
Ron

Tin Indian

BTW... GM states that the LS1 cams base circle is 19.7 mm from the cams centerline to the lobe heel.(thats 0.776”)

A 2002 LS6 cam has a 19.0 mm base circle. (thats 0.748")

As you can see, the high lift LS6 cam has .028" (28 thousands) shorter base circle than the LS1. If you would install that cam in your LS1, you would need .028" [longer] pushrods to keep the exact same lifter preload as you did before. And I would bet that your XE-R has a smaller base circle too.

BTW, Comp Cams may give you the base circle dimension of your cam "across the lobe". This number will be twice as long as from centerline to lobe heel. All you have to do is divide that number in half and compare it to the stock 0.776" spec.

Anyway, why did you install shorter pushrods?

<small>[ March 25, 2002, 06:44 AM: Message edited by: Kimchee and Rice ]</small>

Matt98SS

if anything I would inspect the springs and reinstall the stock pushrods see if that makes any difference

Carlitos

Thanks,Ron. I'll definitely look into that. The shorter pushrods came with the package. I had heard so much about using shorter pushrods, I didn't think anything of it when installing them. Also, the valvetrain is actually pretty quiet with the exception of that "salt shaker" noise.

'Los

Carlitos

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Matt98SS:
<strong>if anything I would inspect the springs and reinstall the stock pushrods see if that makes any difference</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I just recently (about 2 weeks ago) inpected the springs and rockers. The springs were fine but I found one broken rocker (#7 exhaust threw needle bearings). When I replaced the rocker, the valvetrain got a lot quieter. That's when I noticed this "new" noise.

'Los

VINCE

iTrader: (1)

The XE-R is too much for a street car? You've got to be joking.. Next thing I am going to hear is FI is too much for a street car. Nothing is too much. Whatever it takes to get the edge on the car next to you..

SStrokerAce

iTrader: (2)

the ramps are too much, your running cams that need a package that is making peak power at 6600rpm, the intake manifold and other features of the LS engine is not really tuned for that.

I actually think that the new lingenfelter blower is not enough, but I like how he gets there.

There is no such thing as enough, but when it comes to some parts or ways to get there there is such a thing.

TrahnZam WS6

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SStrokerAce:
<strong>You guys are killing me with these XE-R lobes.

I also think those lobes are too much for a street car, but would be good for a 7000rpm drag engine!

Bret</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Whatever! Of the 10 second heads cam cars, at least three (Raughammer, GeorgeC and Cmarsh93Z) all run XE-R lobes or even more aggressive ones. The LS6 intake works just fine for setups peaking at 6600 rpms, and the Holley should pick up even more for the 226+ duration cams. These XE-R lobes are not for drag engines only, they just need a beefier valvetrain (918s will work, but compRs should definately be included as well). Hell, my cam is more aggressive than the XE-R lobes, idles better than my B1, and makes ridiculous torque! I will be installing my compRs within the week, so hopefully that will cure my early peak, probably caused by failure of the stock lifters.

Visceral

iTrader: (1)

Hey Nick,

Your sig says 00', your page says 01'.

Just an fyi <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

\chris

2kvette

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Carlitos:
<strong>Well...finally got through to a CompCams tech and I was told that unless I specify a different base circle, the base circle used is stock. Hrrmmm...guess I'll just have to wait till I can take it apart again.

'Los</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Interesting- the CompCams tech I talked to before said their cams DO use a smaller base circle to allow for the higher lift- sounds like someone at CompCams doesn't know what they are talking about

2kvette

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Carlitos:
<strong>Well...finally got through to a CompCams tech and I was told that unless I specify a different base circle, the base circle used is stock. Hrrmmm...guess I'll just have to wait till I can take it apart again.

'Los</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Interesting- the CompCams tech I talked to before said their cams DO use a smaller base circle to allow for the higher lift- sounds like someone at CompCams doesn't know what they are talking about

Carlitos

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by SStrokerAce:
<strong>Anyways it specificly states that you need to run the dual valvesprings with these lobes, and on top of that change your lifters to Comps Lifters.

It states at the bottom of the XE-R Cam lobe chart that: Design #3720-#3734 use the more agressive XE-R Extreme Engergy Ramps. Hence, increasing spring loads will be required. Comp Cams P#977-16 Springs and Comp Cams P#875-16 Pro Magnum Hyd Roller Lifters are STRONGLY Recomended.
</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I was aware of the recommendations for the XE-R lobes. And if you think about it, CompCams also recommends their lifters with the XE lobes. How many TR224s, B1s, T1s are running with new lifters? From what I understand, most people don't upgrade lifters until they upgrade their heads, and there are alot of cam only LS1s out there. If I'm not mistaken, most of the newer LS1 cams use these XE lobes.

I was hoping that the 918s and stock lifters would work out until I swapped my heads. Then everything would be upgraded.

Again...I'm not real sure that I have any bent pushrods or valves, but with all the signs I've been noticing, that is what I'm leaning towards. I will have more information when I tear into the valvetrain and do a compression test. My post was simply a heads up for everyone to be cautious with these new XE-R lobes.

'Los

SStrokerAce

iTrader: (2)

QUOTE]My post was simply a heads up for everyone to be cautious with these new XE-R lobes.

'Los[/QB][/QUOTE]

'Los,

I'm with you on that one, that's all I'm trying to do also. I'm trying to be the only guy on here to give the guys who are not racing all of the time with their cars a cam option. Hell I have to have a cam in my car so I can get it home in 3-4" of Snow like tonight! That's the difference, that's what I call drivablity.

TrahnZam WS6

Whatever! Of the 10 second heads cam cars, at least three (Raughammer, GeorgeC and Cmarsh93Z) all run XE-R lobes or even more aggressive ones.

I would like too see lobes that are more agresssive than the XE-R Lobes. The only one I can give you that is more agressive than those is the intake lobe on the Z06. The best way to see how agressive a cam lobe is is to divide the lift (at the cam, or all with the same rocker arm) by the duration, then multiply by 1000. The .324 lift on the 2002 LS6 is done with 204 .050 Duration. That works out to be 1.588, where as the most agressive lobe of the XE-R's is 1.554 with the 220 w/ .342 lift.

Raughammer has a 10 second car not just by power but by traction AND low weight. With him in the car it's around 3300 lbs! He's alos a sick driver.

I'm not a big fan of these really high cam lobes, but I do see how these guys get power out of them.

In fact if I cared about having a kick *** drag engine I would use the XE-R lobes and would take the 220 for my intake lobe and then throw alot more duration at the exh. Have you ever seen a GM LS1 cam that has the same int and exh duration? No, they are separted by 9-14 degrees.

Just my thoughts.

Bret

One Monkey

Bret I was just about too say the 2002 Z06 was.... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Carlitos

Well...finally got through to a CompCams tech and I was told that unless I specify a different base circle, the base circle used is stock. Hrrmmm...guess I'll just have to wait till I can take it apart again.

'Los

SStrokerAce

iTrader: (2)

You guys are killing me with these XE-R lobes.

Anyways it specificly states that you need to run the dual valvesprings with these lobes, and on top of that change your lifters to Comps Lifters.

It states at the bottom of the XE-R Cam lobe chart that: Design #3720-#3734 use the more agressive XE-R Extreme Engergy Ramps. Hence, increasing spring loads will be required. Comp Cams P#977-16 Springs and Comp Cams P#875-16 Pro Magnum Hyd Roller Lifters are STRONGLY Recomended.

If this is your street car, then it's time to plop down the cash for these parts, and the new pushrods and valves.

The specs on those springs show that they have a very small inner diameter compared to the 918's or 941's which probably means that the heads need to be machined to fit them.

I also think those lobes are too much for a street car, but would be good for a 7000rpm drag engine!

Bret

SStrokerAce

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by One Monkey:
<strong>Bret I was just about too say the 2002 Z06 was.... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Thanks Brent,

I was almost going to tell them about my 346 Drag cam, but the Hammer Cam is actually good enough. It's my little secret about the 409 cam though.
<img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />