Author Topic: Top end rattle  (Read 2721 times)

Offline shaneo

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Top end rattle
« on: July 14, 2017, 01:38:01 AM »
Hi I have a 468 Chevy engine that has a top end rattle when I back off the gas and goes away when I floor it again does not make rattle when engine is idling only when driving along the Road I'm thinking to replace the Rockers and lifters but I don't know if this will solve the problem if anyone could help would be much appreciated

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Offline SkinnyG

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Re: Top end rattle
« Reply #1 on: July 14, 2017, 02:23:00 AM »
If I understand you correctly, you only get a rattle off-throttle - as in, then the engine is revving down?  That's often a timing chain noise. 

Can you make it do it, and post a video?
The Crusty Chevy: 1977 Silverado, shortboxed & dropped, potato-potato.

Offline shaneo

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Re: Top end rattle
« Reply #2 on: July 14, 2017, 03:50:41 AM »
If I understand you correctly, you only get a rattle off-throttle - as in, then the engine is revving down?  That's often a timing chain noise. 

Can you make it do it, and post a video?
Yeah it's more like when the car is at it's desired speed and you back off a fraction that's when the engine starts rattling around 2 to 3000 revs I tried to take a video over the next couple of days thanks for the feedback

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Online VileZambonie

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Re: Top end rattle
« Reply #3 on: July 14, 2017, 07:21:31 AM »
Sounds like it's pinging. Have you tried retarding the timing? Have you checked the timing? Are you running the correct fuel for your compression ratio?
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Offline shaneo

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Re: Top end rattle
« Reply #4 on: July 16, 2017, 08:36:21 PM »
If I understand you correctly, you only get a rattle off-throttle - as in, then the engine is revving down?  That's often a timing chain noise. 

Can you make it do it, and post a video?
https://youtu.be/UCAHdWKjHfs

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Offline SkinnyG

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Re: Top end rattle
« Reply #5 on: July 16, 2017, 08:59:26 PM »
That sounds more like a heat-sheild rattle, or something loose in the exhaust.  Some sort of vibratory noise. RPM/Load dependent - it's not at all a consistent rattle like valvetrain would be.

Could also be detonation as Vile suggested.  Try disconnecting and plugging the vacuum advance hose and see if it goes away.  If it goes away, it's too much timing.  If it doesn't go away, it's likely something vibrating.
The Crusty Chevy: 1977 Silverado, shortboxed & dropped, potato-potato.

Offline Irish_Alley

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Re: Top end rattle
« Reply #6 on: July 20, 2017, 12:51:28 AM »
cut your exhaust off. problem solved ;)
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline frankentruck79

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Re: Top end rattle
« Reply #7 on: July 21, 2017, 07:27:39 AM »
Not advisable. I did that to mine and you can't hear much of anything but ringing after a ride


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Offline Irish_Alley

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Re: Top end rattle
« Reply #8 on: July 21, 2017, 12:43:31 PM »
But you can't hear the rattle ;)
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes