What happened here???
Thread Starter
Racer
Joined: Jul 2007
Posts: 313
Likes: 0
From: Laurel MS
What happened here???
Discovered bent & missing pushrods(exh & intake) on #7 after 1.6 RR install.(ComCam) All rockers were ck'd TDC & further adjusted @ idle to insure smooth idle & smooth run @ higher throttle.
The missing pushrod was consumed by the engine under the head.
All of this occurred after 1.5K miles on the new rockers.
Tell me what we did wrong gents.
The missing pushrod was consumed by the engine under the head.
All of this occurred after 1.5K miles on the new rockers.
Tell me what we did wrong gents.
Last edited by jim_hewett; Jul 9, 2008 at 07:19 PM.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Were you getting any knock or noise before it self destructed? Might be that the locks on the nuts backed off on the RR and allowed the rod to slip out of the RR and were bent on the next few revolutions. Car would have run like S**T just before, 7 out of 8.
How are the other RR and rods looking?
How are the other RR and rods looking?
Thread Starter
Racer
Joined: Jul 2007
Posts: 313
Likes: 0
From: Laurel MS
Were you getting any knock or noise before it self destructed? Might be that the locks on the nuts backed off on the RR and allowed the rod to slip out of the RR and were bent on the next few revolutions. Car would have run like S**T just before, 7 out of 8.
How are the other RR and rods looking?
How are the other RR and rods looking?
John....after the defecation hit the blade 7 out of 8 didn't sound good!
Considering going to 4130 chrome moly steel push rods. Might be, "under valve springed"...some are using LT4 springs.Was advise by ComCan OEM springs & pushrods were OK. This one has me real gun shy.
Cheers
Last edited by jim_hewett; Jul 9, 2008 at 08:10 PM.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
pushrods
check to see that the center intake hold down bolts aren't too long, riding on the pushrods.
I would go with .080 wall thickness pushrods the next time, and inspect carefully for cracks.
If you have a leaking injector, it's possible one cylinder had fuel in it. Liquids don't compress, and with the piston pushing the fuel up into the valve area, the hydraulic lock may have kept the valves closed, fracturing the pushrods before the valve slightly opened relieving the hydraulic lock, setting you up with a couple cracked or fractured pushrods that failed at a higher RPM.
I would go with .080 wall thickness pushrods the next time, and inspect carefully for cracks.
If you have a leaking injector, it's possible one cylinder had fuel in it. Liquids don't compress, and with the piston pushing the fuel up into the valve area, the hydraulic lock may have kept the valves closed, fracturing the pushrods before the valve slightly opened relieving the hydraulic lock, setting you up with a couple cracked or fractured pushrods that failed at a higher RPM.
Last edited by coupeguy2001; Jul 10, 2008 at 12:20 AM.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
Couple of questions:
1) Stock cam or special? What kind of lift?
2) Guide plates?
3) Any scrapes or worn spots on the rods?
4) Did you check the springs....look at the interior dampener spring...still in one piece? This looks like a piece of flat stock (not round like outer spring) and twisted the other direction.
At 70 MPH you would be not winding it out to a high RPM. And at 70 no hydro lock.
Also assuming that typo...bent rod under intake manifold and not head....that is hard to do.
1) Stock cam or special? What kind of lift?
2) Guide plates?
3) Any scrapes or worn spots on the rods?
4) Did you check the springs....look at the interior dampener spring...still in one piece? This looks like a piece of flat stock (not round like outer spring) and twisted the other direction.
At 70 MPH you would be not winding it out to a high RPM. And at 70 no hydro lock.
Also assuming that typo...bent rod under intake manifold and not head....that is hard to do.
Thread Starter
Racer
Joined: Jul 2007
Posts: 313
Likes: 0
From: Laurel MS
check to see that the center intake hold down bolts aren't too long, riding on the pushrods.
I would go with .080 wall thickness pushrods the next time, and inspect carefully for cracks.
If you have a leaking injector, it's possible one cylinder had fuel in it. Liquids don't compress, and with the piston pushing the fuel up into the valve area, the hydraulic lock may have kept the valves closed, fracturing the pushrods before the valve slightly opened relieving the hydraulic lock, setting you up with a couple cracked or fractured pushrods that failed at a higher RPM.
I would go with .080 wall thickness pushrods the next time, and inspect carefully for cracks.
If you have a leaking injector, it's possible one cylinder had fuel in it. Liquids don't compress, and with the piston pushing the fuel up into the valve area, the hydraulic lock may have kept the valves closed, fracturing the pushrods before the valve slightly opened relieving the hydraulic lock, setting you up with a couple cracked or fractured pushrods that failed at a higher RPM.
Certainly agree w going to .080 Chrome moly steel PR's. (16)
Interesting comment about possible liquid fuel lock. Don't think injectors are the factor since are new w seals. Looking @ this though...thanks again. I'm running FP @ 50 psi a little high...what do you think?
Cheers
Check your 6
Thread Starter
Racer
Joined: Jul 2007
Posts: 313
Likes: 0
From: Laurel MS
Thanks John A. Marker
1. stock cam w 1.6RR..16 valves are lifting 3 thousands over std.
2. Zero guide plates
3. None
4. All springs OEM ck'd OK
Let me qualify bent PR. A bent severed piece (2") was found adjacent spring. The remainder stayed w the cam roller. The other PR simple was missing...assumed in pieces under the head.
Replaced the two PR's in #7 & monitoring closely all looking ops normal.
This "hunk of burning love", is giving me fits lately!
Appreciate you staying w me on this.
Cheers
Check your 6
2. Zero guide plates
3. None
4. All springs OEM ck'd OK
Let me qualify bent PR. A bent severed piece (2") was found adjacent spring. The remainder stayed w the cam roller. The other PR simple was missing...assumed in pieces under the head.
Replaced the two PR's in #7 & monitoring closely all looking ops normal.
This "hunk of burning love", is giving me fits lately!
Appreciate you staying w me on this.
Cheers
Check your 6
Last edited by jim_hewett; Jul 10, 2008 at 06:01 AM.
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Burning Brakes
Joined: Dec 2006
Posts: 936
Likes: 2
From: Tyrone PA
I have an L98, but when I installed roller rockers I didn't know about the drip tabs in the valve covers needing removed. They snapped off and got caught in the rocker slot between the top of the rocker and the rocker nut. Bent all 16 pushrods, most of them severely. Bent the rocker studs too. If the top of your rocker contacted something or if something managed to get in the rocker slot it will bend the pushrod. If you have a lifter that pumped up it could cause a valve to hang open and contact the top of the piston. Likely would damage the valve but it is possible if it happened at a low rpm that it would bend the pushrod, saving the piston and valve. Is your preload set correctly? I went 1 turn past 0 lash with mine and it seems to work fine.
Thread Starter
Racer
Joined: Jul 2007
Posts: 313
Likes: 0
From: Laurel MS
I have an L98, but when I installed roller rockers I didn't know about the drip tabs in the valve covers needing removed. They snapped off and got caught in the rocker slot between the top of the rocker and the rocker nut. Bent all 16 pushrods, most of them severely. Bent the rocker studs too. If the top of your rocker contacted something or if something managed to get in the rocker slot it will bend the pushrod. If you have a lifter that pumped up it could cause a valve to hang open and contact the top of the piston. Likely would damage the valve but it is possible if it happened at a low rpm that it would bend the pushrod, saving the piston and valve. Is your preload set correctly? I went 1 turn past 0 lash with mine and it seems to work fine.
Cheers
Last edited by jim_hewett; Jul 11, 2008 at 08:59 AM.