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[Z06] 2006 Z06 noise/miss? Katech Torquer and PRC heads
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[Z06] 2006 Z06 noise/miss? Katech Torquer and PRC heads
Car: 2006 Z06. Katech Torquer cam. Believe it has the Comp trunion upgrade. PAC 660 dual springs. Previous owner did have a valve spring fail and replaced all springs. PRC265 heads from Texas Speed. Work was done by the previous owner.
So, cruising down the highway about 55 in 5th, exhaust tone changed. I got in and out of the gas and felt the car randomly missing. Figured electrical/electronic. When I stopped and opened the door, i thought i heard something internal maybe. Shut it down for an hour. Fired it back up and drove home about 10 miles. The miss was there at first and seemed to go away. Got home and tried to listen. Thought I heard a squeak or squeal in the engine. Had a friend come over and take the attached video. You can hear it in the video after a quick rev. Thoughts? Is there something there?
I was guessing a lifter issue at first but didnt want to bias the replys. Would that explain or present with the miss that I descibed as well?
possibly... If the lifter collapsed or something else broke. To hard to diagnose via a slight squeel on a video.
I think my first step would be pulling the valve covers and inspecting for anything obvious broken. Try to move push rods up and down(shouldnt really get any movement). Then move on from there.
Pulling the heads sucks, but if its lifter wheels, you might be doing a lot more than pulling the heads.
What was the oil pressure?
Also the comp trunion upgrade is ****. I would replace it while I was in there regardless. Do some searching and you will see all the failures here on the forum.
Yes, disgnosing via video is tough. I appreciate any input. Oil pressure stayed good the entire time. I might pull valve covers and take a look. Thats as deep as Ill probably go though. Past that, Im looking for a shop. I have read some negative things around the Comp “upgrade” but dont know enough to dispute it.
At this point the noise was still pretty faint. Ive heard some far worse via searching. If its a lifter, Id hope to get away with lifters and a cam replacement perhaps?
1) Ensure all spark plug wires are seated on both the plug and coil. Be 100% certain of this, even if it means pulling them off and re-installing.
2) Remove both valve covers and inspect rockers and springs. Make sure no rockers are loose (just wiggle them) and look intact. Inspect springs and make sure none are broken. Look very carefully with a flashlight (inner and outer spring). Look under the valve covers as well and make sure that the rockers aren't hitting the inside of the valve cover. (you will see marks)
The Comp trunnions are junk and prone to failure. Ditch them as part of whatever fix you end up with. Either stick with OEM stock rockers or go Straub, CHE or Smith bros trunnions.
You could try running seafoam through the motor. If it is a stuck lifter, this could help. Might be worth a shot before a tear down.
possibly... If the lifter collapsed or something else broke. To hard to diagnose via a slight squeel on a video.
I think my first step would be pulling the valve covers and inspecting for anything obvious broken. Try to move push rods up and down(shouldnt really get any movement). Then move on from there.
Pulling the heads sucks, but if its lifter wheels, you might be doing a lot more than pulling the heads.
What was the oil pressure?
Also the comp trunion upgrade is ****. I would replace it while I was in there regardless. Do some searching and you will see all the failures here on the forum.
The Comp trunnions are junk and prone to failure. Ditch them as part of whatever fix you end up with. Either stick with OEM stock rockers or go Straub, CHE or Smith bros trunnions.
My guess is a lifter failure as well by the sound of it. I assume the broken spring was the .675" spring set that the PRC heads used to come with...those had issues, and that's why PRC's come with .660" springs now. Work was done by the previous owner himself, or he hired a shop? I'm wondering if measurements were taken for proper pushrod length. Dont want to jump the gun here...but I'd park it and start pulling things apart.
The previously failed springs were the .675 I believe. .660’s in now. The previous owner had the work done. I believe I have paperwork. Im at work so i cant dig up the previous posts but there is a post history around the car, the cam, the heads, etc... under previous owners handle here on the forum. Username Lancefitzgiben if your so inclined to look.
Good info and answers here so far. Its appreciated folks.
I bought a modded(HCI) C6Z and the previous owner had Comp Trunions and PRC .675 springs that came with the heads from TSP. I have had to replace both. If you go to my threads you will see pics of the Comp Trunions how they were making grooves into the rocker. Approx 5k miles on them (about the time they fail on people). I took these out and replaced with Straub. Bronze trunion now instead of the needle bearing Trunions.
Next point.. was getting a misfire code when going WOT around 4-4500 rpm.. you could feel it accelerating and then level off and not pick up steam. Took it to my tuner and he drove it, put it on the dyno and it made 522/514. Still misfiring. So we replaced the #4 coil pack. Still misfire. I told him I wanted to keep it as cheap as possible so he said keep rpm under 4K and limp it home but when you get home pull the valve covers and check for a broken Spring. I did so and #4 intake and #2 exhaust springs were broken. I was baffled that the thing still ran with broken springs. Luckily it was dual springs so the inner spring held on to keep the valve from dropping.
After doing some some research and asking around I found that quite a few guys had problems with the PRC .675 springs and steered others from them. I replaced them with PAC 1206X kit and haven't had a problem since. Made 575/506 to the wheels.
So I say check for a broken Spring and if everything else turns out good swap those comp Trunions and prc springs out for better parts.
Joe, sorry you're having more issues with the car!
The rockers do have the trunnion conversion. I didn't have issues here but before I had them installed I went over all of them with a fine tooth comb. I did see some tolerance issues that, if not noted and compensated for, could possibly have the aftermarket parts coming in contact with the head. Not sure what I'm explaining that well, but if anything in the rockers has moved around over time, that could cause interference. Check out all the rockers and see that the trunnions are all symmetrically seated.
All the lifters and trays were changed out for brand new GM units - it'll be in the receipts. Pushrods are TSP aftermarket. My installer measured and then we ordered the pushrods. Obviously a mistake could have been made here but I trust him and I think a pushrod length discrepancy would have shown me issues a long time ago.
Now that I have experienced a broken spring and the subsequent valve float, it's easier for me to identify that trait. I didn't experience any unusual noises, it would just fall on its face at 4500 or so and throw black smoke. Those new 660 springs were obviously a lot softer than the 675s, which were completely solid in your hands with no give what so ever.
Thank you both for your additional thoughtful replies. It's providing me some better clarity on what could be going on and a more clear path. Ill be sure to keep everyone updated.
Well, I spoke with Todd at Doug Rippie Motorsports near Minneapolis. I made an appointment to bring it to them next week. Anyone have any tips on tying these down...? Ha... Ill let them take a look. I guess if it turns out to be minor, Im sure we can find something there to spend money on. If it turns out to be major, I guess the fun budget will go towards that. Either way Ill be more comfortable with what im left
Loaded up and ready to head for DRM Tuesday morning. Hopefully its more minor than serious and I can devote the budget to a few other things Id like done.
Well, got the car dropped off to DRM today. Cool place! Doug Rippie and Todd both took a listen. They’re both leaning towards a lifter as well. Seems it’s very early in the failure and hopefully it didn’t do too much extra damage. Hopefully they can dig in next week.
10-02-2017, 07:56 AM
2006 Z06 noise/miss? Katech Torquer and PRC heads
