what does it sound like when....
10-14-2004, 02:30 PM
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what does it sound like when.... a rocker hits a valve cover?? I just installed a cam with a 632 lift and have been trying to get it to idle, all of a sudden I hear a loud poping metallic sound, maybe once every 20 seconds. like the crazy drum sound on metallicas St. Anger album (closest thing I could think of 
)
took the covers off and there are some small knicks on the drivers side, but doesn't look like a LOT. was horrified that it was a PTV issue initially
EDIT: NOT the rocker/cover clearance! I'm lost on this one as well as quite a few of my mechanic friends... look down for more details
) took the covers off and there are some small knicks on the drivers side, but doesn't look like a LOT. was horrified that it was a PTV issue initially
EDIT: NOT the rocker/cover clearance! I'm lost on this one as well as quite a few of my mechanic friends... look down for more details
Last edited by 383ss; 10-14-2004 at 11:53 PM.
10-14-2004, 03:01 PM
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you're just not up on your luck lately dude!! if its only once every 20 seconds, then thats kinda odd. the only thing you changed was your cam? also curious type of rockers you are running.
10-14-2004, 11:42 PM
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rockers are yella terras. I found where they were hitting the valve covers, clearanced that and it is still doing it.
I have a totally new setup. 408 with a 246/250 .632 cam, crane double springs and Milner lifters. it doesn't do it on initial startup, maybe after 30 or 40 seconds it will do it every 10-20 seconds. kind of like a bongo drum sound if that makes any sense... sticky lifter maybe???
I have a totally new setup. 408 with a 246/250 .632 cam, crane double springs and Milner lifters. it doesn't do it on initial startup, maybe after 30 or 40 seconds it will do it every 10-20 seconds. kind of like a bongo drum sound if that makes any sense... sticky lifter maybe???
10-15-2004, 12:35 AM
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I dunno man, it doesnt make sense that a rocker would just hit the rocker every now and then. It should peak just as high every time. Maybe its just not making the sound loud enough for you to hear every time???
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10-15-2004, 08:36 AM
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Use a mechanics stethoscope and listen to the top of your valve covers, then listen on points of your headers, that may help pinpoint where the noise is coming from.
10-15-2004, 10:33 AM
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no bent pushrods... have the rockers off. it now makes the noise when I just turn the engine over with no ignition. it did NOT do this when I was initially priming the oil pump.
10-16-2004, 08:45 AM
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I did replace my Comp R's with Milner lifters. lifters are just a drop in replacement, right? what is there to screw up with a lifter install?? I'll take the heads off asap and check them out.
10-16-2004, 10:59 AM
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I didn't think you had to pull the heads on these motors to get to the lifters? I thought you just took off the intake manifold?
Anyway... I have heard that lifter bores sometimes need to be machined because they sometimes lose their perfect cylindrical shape. Now.... I am going out on a limb here, but possibly the lifter bore has lost its perfect shape, and these new lifters are fot a certain shape, and thereforw, every once in a while, one is getting stuck and leaving a valve open and a piston is just barely hitting it. After all, these are what they call "interference" engines right.... meaning that if a valve is left all the way open that when a piston reaches TDC they will hit.
Let me know if I am wrong on this one or it is a stupid idea.....
Anyway... I have heard that lifter bores sometimes need to be machined because they sometimes lose their perfect cylindrical shape. Now.... I am going out on a limb here, but possibly the lifter bore has lost its perfect shape, and these new lifters are fot a certain shape, and thereforw, every once in a while, one is getting stuck and leaving a valve open and a piston is just barely hitting it. After all, these are what they call "interference" engines right.... meaning that if a valve is left all the way open that when a piston reaches TDC they will hit.
Let me know if I am wrong on this one or it is a stupid idea.....
10-16-2004, 12:24 PM
#17
Originally Posted by derek_silvy
I didn't think you had to pull the heads on these motors to get to the lifters? I thought you just took off the intake manifold?
