GM Racing Lifters Failed in New Motor
04-29-2007, 03:44 PM
#21
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BillC5, I'm interested to know what you think was causing the ticking sound that originally alerted you to the problem? Is it possible that the crack in the body of the lifter was allowing oil pressure to bleed off and it was valve train lash that you were hearing?
For what it's worth, when I installed mine I also had to go with a much shorter pushrod than I anticipated, a 7.325, to get the proper preload...
This all makes me very nervous...
For what it's worth, when I installed mine I also had to go with a much shorter pushrod than I anticipated, a 7.325, to get the proper preload...
This all makes me very nervous...
04-29-2007, 04:19 PM
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04-29-2007, 05:29 PM
#23
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Originally Posted by billc5
I'm wondering why I should contact anyone before posting? What materially changes the content of my post by contacting Lingenfelter before during or after I discover a part failure? A part has failed and there is a picture of the failure.
I suggested that you include in your first (or subsequent post) exactly what LPE tech said about the problem. That would more than likely answer many of the questions that occur to readers of this thread. If you haven't contacted LPE, why not?
Please tell us how the skirt of a lifter and specifically 2 out of 16 Brand New Lifters could suffer failure from the hands of the installer? given the evidence of the photographs presented.
I would think that the mode of failure is in the design or the material or in the manufacturing process. The skirts at the failure location are only 0.020" thick. So could the oil pressure between the bore and Lifter reach 2000psi? perhaps someone in the advanced section could tell us as this type of question is not appropriate in that section?
I would think that the mode of failure is in the design or the material or in the manufacturing process. The skirts at the failure location are only 0.020" thick. So could the oil pressure between the bore and Lifter reach 2000psi? perhaps someone in the advanced section could tell us as this type of question is not appropriate in that section?
The failure, which appears to be somewhat unique, could have resulted from something as mundane as valvetrain instability due to parts like springs, spring loads, rockers and pushrod strength not being compatible with the lifters and the lobe profiles at the rpm the engine was run. A complete list of valvetrain parts, including spring installed heights, especially for the effected cylinder(s) would also be useful for someone trying to explain the failure on line, or on the phone.
Let's say, just for grins, that the spring installed heights on the failed lifter holes were not checked at installation, and perhaps those spring seats had been "touched-up" sometime in the past, or during the reconditioning of the heads during this modification. It has happened. Low seated pressure, perhaps just on these two holes, might cause the lifters to go through some motions and displacements the should not have at high rpm. This valvetrain "instability" can result in impact loads on parts which were not designed to withstand impact loads. In such a scenerio, improper buildup (installation) could be the root cause.
I wasn't pointing fingers; I was suggesting places to look for problems.
Yes, obviously something was wrong, but without a thorough investigation of all the parts, clearances, installed heights, etc. of the bad holes and the good holes, narrowing down the root cause is darn near impossible.
It difficult not to get emotional when something like this happens, but the failure wasn't caused by whatever we want to be the cause, but by physical conditons which just obey Ma Nature's laws. We don't always like the real answers.
My $.02
04-29-2007, 06:29 PM
#25
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I have a set of Caddy Race Lifters on order for over 2 months now. I was told by SDPC that GM was waiting for a new bath to be made up...and inspected before shipping them out to the vendors. Could this be the reason WHY?
My engine has a 224/224 Comp Cam and will be installing 243 Patriot heads milled to 62cc. Hope these will be trouble free..
My engine has a 224/224 Comp Cam and will be installing 243 Patriot heads milled to 62cc. Hope these will be trouble free..
04-29-2007, 06:35 PM
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Originally Posted by LS1_TA_2002
Worst case scenario of this classic... maybe?
http://www.pistonslap.com/tsb/020601038.htm
http://www.pistonslap.com/tsb/020601038.htm
Very Good Call!!! This is certainly worth pursuing. They don't suggest that the lifters need to be replaced from this condition.
We will inspect the oil pump, The tick started spontaneously after several hours of running with good oil pressure
. I was at 3/4 throttle, in 1st, and 4000 rpm when something let go (besides the tires) and the tick started. There was then a noted drop in Oil pressure, pressure went to 16psi at 575 rpm and 190F Oil temp, with 5w30. The tick was continuous after that and I could not say that its was getting any worst, as I burned another tank of gas.
It looks like the tick is caused from the lifter hanging up in the bore. The cam has been removed and we have another GT2-3 cam to compare this one with.
"I surmise that the lifter damage is on the shroud face on the opposite side of the cam rotation.
Yes?"
YES, The damaged face and bore is on the side you mentioned, the lee side of the rotation, which is in compression always.
I had yet to go wide open past 5000rpm with this motor and the heads are stock 243 castings with stock springs and valves.
"Let's say, just for grins, that the spring installed heights on the failed lifter holes were not checked at installation, and perhaps those spring seats had been "touched-up" sometime in the past, or during the reconditioning of the heads during this modification. It has happened. Low seated pressure, perhaps just on these two holes, might cause the lifters to go through some motions and displacements the should not have at high rpm. This valvetrain "instability" can result in impact loads on parts which were not designed to withstand impact loads. In such a scenerio, improper buildup (installation) could be the root cause. "
This is excellent information and much appreciated and thank you for responding.
Let's say that the root cause of the lifter failure is still not known and keep pursuing the mater as has been suggested. I have to wonder why I'm the only one to report this failure, hmmmmmmm.
one last point, there appears to be inconsistency with the profile of the lifter skirts, compare the side by side view, at 0.020" thick it just looks too delicate for the application. Even if the root cause is in the valve train elsewhere. if the seats are out .050 do you really what your lifters breaking first?
04-29-2007, 07:05 PM
#27
"YES, The damaged face and bore is on the side you mentioned, the lee side of the rotation, which is in compression always."
AH HA.
The compression to the side wall of the lifter bore hole is only on the upstroke rotation of the cam.
I would almost bet that the hole has an edge or rise on it that scored and cracked that lifter on that side.
As for the one that looks like it hit something (the area you circled) that is interesting, but it could have happened when you installed or removed.
Like I mentioned before, the design of the new lifter allows the shroud to follow the roller past the hole edge.
I believe this is a no no.
AH HA.
The compression to the side wall of the lifter bore hole is only on the upstroke rotation of the cam.
I would almost bet that the hole has an edge or rise on it that scored and cracked that lifter on that side.
As for the one that looks like it hit something (the area you circled) that is interesting, but it could have happened when you installed or removed.
Like I mentioned before, the design of the new lifter allows the shroud to follow the roller past the hole edge.
I believe this is a no no.
04-30-2007, 01:26 PM
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update the valve train has now been checked.
we straight edged the valve stems which were 100% even.
The lifter bores were miked and are within spec.
The valve springs are good at 90# per spec, LS6
the Cam bearings have slight marring but otherwise like new.
the cam was checked against another spare and found identical.
So we are rebuilding without the GM racing Lifters and have found no other cause for the lifter failure.
we straight edged the valve stems which were 100% even.
The lifter bores were miked and are within spec.
The valve springs are good at 90# per spec, LS6
the Cam bearings have slight marring but otherwise like new.
the cam was checked against another spare and found identical.
So we are rebuilding without the GM racing Lifters and have found no other cause for the lifter failure.
04-30-2007, 09:11 PM
#32
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I had a roller break off one of my GM lifters. Bizarre, no particular reason, it just broke the hell off and went through the motor. so, I bought a Texas Speed short block and went on my merry way. I'm running Morels now, but they are pricey. I lucked out and got a new set off a guy on ebay for $200.
05-01-2007, 02:57 AM
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90# may be the spec with the stock cam, but with a performance cam you are bouncing the valves off the seats and banging the lifters on/off the lobes. These motors are known to float the valves in stock form as is. I do not run hydraulic rollers below 125# and for performance stuff aim for 135-145#. The LS6 springs may work with the LS6 lightweight valves...barely - but you don't even have those in the Patriot heads.
Spring pressure is where my money is at.
Spring pressure is where my money is at.
05-01-2007, 06:41 AM
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Originally Posted by machinistone
90# may be the spec with the stock cam, but with a performance cam you are bouncing the valves off the seats and banging the lifters on/off the lobes. These motors are known to float the valves in stock form as is. I do not run hydraulic rollers below 125# and for performance stuff aim for 135-145#. The LS6 springs may work with the LS6 lightweight valves...barely - but you don't even have those in the Patriot heads.
Spring pressure is where my money is at.
Spring pressure is where my money is at.
Last edited by billc5; 05-01-2007 at 08:47 AM.
05-01-2007, 07:23 PM
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By bouncing the lifter up/down you are basically taking an air-hammer to the bottom of the lifter - bell-mouthing the bottom part which will lead to those stress cracks - I have seen it before.
Not saying that is definitely the cause, but from where I stand without looking at the parts myself, that is my best educated guess.
Not saying that is definitely the cause, but from where I stand without looking at the parts myself, that is my best educated guess.
10-07-2007, 03:19 AM
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The race lifters are heavier than stock btw.Due to heavy duty construction to withstand higher spring pressures.I have had them both apart and compared them side by side.So im guessing valve float was the root ,or mabe lifter chatter would better way to discribe what i'm thinking.
Last edited by SincalT/A; 10-07-2007 at 04:56 AM.
