Exhaust noise or valve flutter?

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89vette
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Exhaust noise or valve flutter?

Post by 89vette »

In consideration of your vote on the original of this flutter, who thinks 25-30k is the most I should get out of AFRs upgraded beehive springs...on a 340 lobe (.544) with 214 duration? IOW...Is that an aggressive enough lobe that would need new springs after 30k (7yrs). I had hoped they'd last longer. OTOH, I'm not convinced this is valve flutter. Might be something loose in exhaust/cats.

https://youtu.be/RmduyHJSgyM
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Re: Exhaust noise or valve flutter?

Post by Newold1 »

Have you tested the springs on the engine? How do they compare in poundage to the spring advertised as new? Until you do, most everything you are pondering is a WAGMAR-wild ass guess made at random. :wink:
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89vette
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Re: Exhaust noise or valve flutter?

Post by 89vette »

Thanks for making me aware of that option! :hello2: I wonder what type of shop would have the tool/machine necessary to measure spring strength? I will look into a couple of shops nearby.

That said, the question about the nature of the noise isn't predicated on spring pressure (though it could skew the guess one-way or another). To me, it doesn't sound like valve flutter. Maybe (as an optimistic), I'm hoping for exhaust noise. This has been posted in a couple of forums for a couple of days. Since no one has replied (in either place), that also makes me think this isn't valve flutter....assuming it would be more readily recognizable.
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Re: Exhaust noise or valve flutter?

Post by MadBill »

The Monday post above somehow looks like we've picked up the thread in mid-stream, but assuming it is complete, I'd say there's zero chance that it has anything to do with valve springs. 95% likely it's a loose exhaust bracket, muffler baffle or something similar.
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Re: Exhaust noise or valve flutter?

Post by 89vette »

Thanks "MadBill". I can see why the wording of my first post seems odd. This IS all of the thread.

My thread was written to solicit 2 pieces of feedback:
1) Dual-hive spring*** longevity (expectancy) on a 214 duration .544 lobe (1.6rr) running less than 5k rpms (peak) -- and --
2) opinions on origin of my exhaust noise.



*** Don't remember what (upgraded) springs I put on my 195 Eliminators. Hopefully they keep records. If I HAD to guess, 155# sticks out in my mind. Can't remember if I upgraded retainers to lighter weight....probably not due to lower rpm use. I picked 155# in hopes of longevity AND control because Bullet's .340 lobe was their most aggressive lobe on a 214 duration cam. (Lots of talk [at the time] about Comps XFI cams maybe, possibly being a hair too aggressive on the ramps).
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Re: Exhaust noise or valve flutter?

Post by tresi »

Sounded like well muffled exhaust popping on deceleration to me but I can't hear crap anymore.
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