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Discussion Starter #1 (Edited)
buddys car. 396 BBC all fresh. 600 lift solid fl tappet. there is a squeaking noise from under the valve covers, cant pinpoint it. tried 2 sets of roller rocker and second set sounds worse, ch moly pushrods. only does it at idle, touch the throttle and it quits. any thoughts? both sets of rockers were used sets
 

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The ball part may not be worn the same as the push rod, I would look to see the witness marks it should ride on the oil not scrape it off, or hitting the retainer
 

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Sounds like maybe a guide issue, seen guides so loose that exhaust was coming up the valve lol,
also seen too tight causing snapping and other wierd noises
 

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Butch
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If the crankcase is not breathing it can cause a squeak or whistle.
 

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take the valve covers off, fire it up and let it idle.. look and see if you can find it... its not the vavle guides makeing noise and i have never heard of a crankcase not breathing causing noise. but who knows. give it a look when you can see all the parts moving and makeing the noise. make sure all the pushrods are getting oil and the rockers balls or bearing are getting oil. I bet you will find your noise that way.
 

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Bracket racer
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Mechanics stethoscope, or put your hands on the valve cover and see if you feel anything through the valve cover.
 

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Butch
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take the valve covers off, fire it up and let it idle.. look and see if you can find it... its not the vavle guides makeing noise and i have never heard of a crankcase not breathing causing noise. but who knows. give it a look when you can see all the parts moving and makeing the noise. make sure all the pushrods are getting oil and the rockers balls or bearing are getting oil. I bet you will find your noise that way.
Just like an un-vented fuel cell will squeak/whistle

Had a guy put a crate engine in and I had to look at it, it would squeak/whistle at idle. What I found was on the breather side there was a plug under the breather and the PCV on the other side causing a squeak/whistle (Same principle as the un-vented fuel cell). It didn't do it when you rev the throttle due to the vacuum DROP
 

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Butch
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makes a suckin squeal.. lol I can see how that could happen. its sometimes hard to describe a sound on here.
Makes you feel like that AAMCO commercial, huh? LOL
 

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I built a 302 years ago and didnt have hardened pushrods (waiting on them and wanted to hear it run) they rubbed the guide plates and made a "squeeling" sound where it was eating into the push rods. Probably not your issue, but something to check.
 

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It's actually my car. Sorry it took me so long to reply. All seem like good ideas to look into. I've run it without valve covers on but can't exactly pinpoint the noise. I've tried 2 sets of used crane roller rockers but the noise is still there. I was leaning towards it being a bad rocker or maybe a few bad rockers but I find it unlikely that both sets make noise. If it was a crankcase ventilation problem shouldn't the noise stop when I run it without the valve covers on? Thanks
 
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