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| djxib | Tapping noise above 2000 RPM part two | ||
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Senior Guru
 
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(from previous thread). 1992 383 LT1 / LT4 heads + Vortech
I got fed up not being able to work out where the tapping noise is coming from. So I removed the supercharger belt and now I can clearly hear the tapping at idle. The tapping gets much worse and very loud above 2000 RPM. I pulled both valve covers and it seems to be more pronounced at #8 exhaust. I re-set the lash and made no difference - still taps like a mofo. To be honest the tapping seems centered at the rear of the intake. So I threw half a can of seafoam in the crankcase and ran the car for 10 minutes and I am leaving overnight. If it is gone then I had an sticky lifter (which I actually dont hold out much hope for). If it is still tapping, I will remove the intake and throw a new set of lifters in there plus inspect everything. If it is a lifter it is weird because I put the current set of LS7 lifters (according to SDP they are compatible) about 10,000 miles ago. Guru comments welcome... |
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Posted on: 2010/7/13 1:41
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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| Matatk | Re: Tapping noise above 2000 RPM part two | ||
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Webmaster
 
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I would suspect a lifter, myself, or a noisy rocker. Are your rocker arms in good condition? What about the pushrod - not bent or damaged?
LS7 lifters should be fine AFAIK. Matthew |
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Posted on: 2010/7/13 1:52
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
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| BillH | Re: Tapping noise above 2000 RPM part two | ||
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The Stig Moderator
 
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Have you tried stickin' a screwdriver in your ear and putting on top of both #8 rocker arm studs?
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Posted on: 2010/7/13 1:55
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Every man dies but not every man lives. |
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| bogus | Re: Tapping noise above 2000 RPM part two | ||
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Grand Imperial Pooh-Bah
 
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what Bill said.
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Posted on: 2010/7/13 2:00
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The single biggest problem with communication is the illusion that it has taken place. - George Bernard Shaw Education is the best tool to overcome irrational fear. - me |
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| Livin_the_dream | Re: Tapping noise above 2000 RPM part two | ||
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Senior Guru
 
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Quote:
x2 located many of noises that way! |
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Posted on: 2010/7/13 2:05
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| pianoguy | Re: Tapping noise above 2000 RPM part two | ||
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Guru Emeritus
 
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Let's hope it isn't a spun bearing.
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Posted on: 2010/7/13 2:45
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1996 LT4 �Before you criticize someone, you should walk a mile in their shoes. That way when you criticize them, you are a mile away from them and you have their shoes.�- Jack Handey |
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| dan0617 | Re: Tapping noise above 2000 RPM part two | ||
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Senior Guru
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Bent or burnt exhaust valve?
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Posted on: 2010/7/13 10:57
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´89 Vert, 383, 230/236 cam, AFR 195's, LT Headers, HSR intake, 2800 stall, Zex 200 shot, ET Street Radials, tune by me. Runs were with D36 3.07's. On spray, 10.55 @ 132.78, 1.55 60 ft. On motor, 12.08 @ 113.15, 1.66 60 ft. |
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| djxib | Re: Tapping noise above 2000 RPM part two | ||
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Senior Guru
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Yep - used a mechanics stethoscope to home in on #8 exhaust. But to the "naked ear" the noise is coming from the intake. Will post results later....
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Posted on: 2010/7/13 11:37
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Andy 1996 Greenwood Collectors Edition LT4 Previously 1992 Convertible Polo Green. 383 LT1/LT4 forged/balanced. V7-YSi, Alky. 608RWHP... Now sitting at a dismantler with a salvage title. Still runs... |
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