Rocker Arm Noise - '65 GTO - Pontiac GTO Forum
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post #1 of 26 (permalink) Old 04-05-2017, 06:08 PM Thread Starter
 
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Rocker Arm Noise - '65 GTO

This may sound crazy but I'm getting excessive rocker arm noise with the valve covers on, when they're off there is no noise. Today I adjusted the valves and with the valve covers off there was no unusual or excessive noise. It's as if the valve covers are amplifying the normal sound of the valve train. It's a 389 with '69 400 cast iron heads and stamped steel rocker arms. I bought reproduction chrome valve covers for a '65 389, they do not have baffles. Would valve covers with baffles be quieter? Could the stock rockers be contacting the valve covers? Does anyone where I can buy valve covers with baffles? I've already searched several web site. I'd like to know if anyone else has had this problem and how is was resolved. Thanks!
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post #2 of 26 (permalink) Old 04-05-2017, 09:15 PM
 
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Sounds odd. It may be as you mentioned, the rockers could be hitting the tops of the covers. If you put your hand on top of them do you feel any movement? Maybe something as simple as a double valve cover gasket may do the trick IF you need to raise the covers a tad bit. Aftermarket does not always mean factory correct and they may be an incorrect/too short of height.

Just a guess.
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post #3 of 26 (permalink) Old 04-06-2017, 12:38 PM
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Pull the covers off and examine both the insides of the covers, and all the "movey" parts in the heads very carefully, looking for any 'shiny spots' that don't seem to belong there. Those will be a telltale of something that's making contact.

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post #4 of 26 (permalink) Old 04-06-2017, 08:58 PM Thread Starter
 
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I did feel some movement when I put my hands on the valve covers. If a second gasket is enough to clear the valve train, I would think it should it be glued to the first gasket, correct? I will also inspect the inside of the v covers for contact marks. Thanks!
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post #5 of 26 (permalink) Old 04-06-2017, 10:18 PM
 
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I think the valve covers for old 389s were different from the covers of the 1967 and later Pontiac V8s. The old 389s had that hump on the opposite ends of the valve cover. Maybe that doesn't make any difference, but the valve covers on a 400 look different from those off a 389.

Do you still have the valve covers to the 400 heads you have on your 389? You could put them back on and see if the noise goes away or changes.

I know a lot of those reproduction parts fit like O.J.'s glove, so it won't be a surprise if your problem stems from a bad fit of the reproduction valve covers.
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post #6 of 26 (permalink) Old 04-06-2017, 10:33 PM
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Originally Posted by Roqetman View Post
I did feel some movement when I put my hands on the valve covers. If a second gasket is enough to clear the valve train, I would think it should it be glued to the first gasket, correct? I will also inspect the inside of the v covers for contact marks. Thanks!
Examine your rocker arms and valve retainers for shiny spots as well...

Also, previously you mentioned that you had 'adjusted the valves'. Is your valve train stock? As in factory Pontiac rockers, studs, balls, and nuts? If so, they aren't adjustable... The factory system is designed such that you torque the nuts down onto the 'bottleneck' on the stud. I forget what the exact torque spec is...

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post #7 of 26 (permalink) Old 04-07-2017, 06:49 AM Thread Starter
 
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They appear to be stock stamped steel rocker arms with screw in studs and push rod retainers. We adjusted the rockers with the engine warm and at idle, we backed off the nut until the rocker started clicking, then tightened the nut down 1/2 turn. If that is not the correct procedure, then I need to find the torque spec and proper procedure. The engine block is the original numbers matching 389, the heads are cast iron from a 69 400. The number cast on the center exhaust ports appears to be 48 but the 8 is hard to distinguish on both heads.

When I bought the car in Aug 15 it had chrome Edelbrock V covers and they are fairly tall. The after market valve covers I ordered for a '65 389, were a lower profile and at the time didn't realize the heads had been changed. They gave it the stock appearance I wanted. But now I'm going back to the Edelbrock to see if the noise goes away... I bet it will. Thanks for your input!
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post #8 of 26 (permalink) Old 04-07-2017, 09:03 AM
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If you have all factory style parts:



Even if you have different rocker arms --- what matters is the stud, ball, and nut... These are not adjustable, regardless of whether the studs are pressed in or screwed in. The nut is designed to seat onto the bottleneck shoulder on the stud. Torque to 20 lb.ft. Done. If they're not seated like this, they WILL back off and you'll get noise.
However, it doesn't take much modification (head milling, etc) to throw everything out of whack. So in order to make the valve train adjustable one MUST use some sort of locking nut (poly lock) such as something like these:



...that have a jam screw in the center that, when tightened down against the top of the stud, will hold them in position.

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post #9 of 26 (permalink) Old 04-07-2017, 04:25 PM Thread Starter
 
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BearGFR, I have the factory style rockers shown in the first picture with hydraulic lifters and screw in studs. Can you tell me the procedure to tighten to 20 lbs or advise me of a link for instructions? Thanks!
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post #10 of 26 (permalink) Old 04-07-2017, 04:34 PM Thread Starter
 
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