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#1
03-13-2011, 01:39 PM
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Opinions on engine noise please
Can you all give me a opinion as to whether this sounds like an exhaust leak? It could be the intake crossover or the header/s but it does get louder the warmer it gets.
http://s1189.photobucket.com/albums/...nt=TANoise.mp4 Thanks for looking |
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#2
03-13-2011, 02:29 PM
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I hear your lifters loud and clear.
Nothig on the exhaust. If the exhaust crossover is leaking then you can put your hand close to the intake at the passage and you should feel hot exhaust blowing.
__________________
Carburetor building & modification services Servicing the Pontiac community over 25 years |
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#3
03-13-2011, 03:40 PM
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same as above.
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#4
03-13-2011, 06:35 PM
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Shaker455,
would it be possible for the crossover to leak from the bottom portion of the passage? I can't hear anything from above with a stethoscope. Also, you say you can hear my lifters meaning they are faulty or just noisy? |
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#5
03-13-2011, 06:38 PM
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That's definitely lifter noise, or more likely, rocker arm noise. Are you using a XE268 comp cam with roller rockers? It will be less pronounced once the valve covers are on. My 455 sounds similar and it's annoying. No amount of adjustment will alleviate it. Will probably pull this cam and go back with stamped rockers.
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#6
03-13-2011, 06:56 PM
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Sounds like valvetrain noise to me.
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#7
03-13-2011, 09:30 PM
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Quote:
Yep those lifter & rocker are loud. I hope your running oil with plently of Zinc in it or an additive.
__________________
Carburetor building & modification services Servicing the Pontiac community over 25 years |
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#8
03-13-2011, 10:40 PM
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The gaskets are the right year fel-pro's and have been using a half bottle of EOS with 15W40 CI4 diesel oil for well over 5 years. Should I think about pulling the cam?
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#9
03-13-2011, 11:06 PM
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What do you have the lash set at?
__________________
24 beer in a case. 24 Hours in a day. Coincidence? I think not. " Steve Wright" |
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#10
03-13-2011, 11:16 PM
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They were all set at 3/4 turn or just under that as I went to a half turn then snugged up both the nut and set screw together (after turning down the set screw first).
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#11
03-14-2011, 12:45 AM
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Put a vacuum guage on it and see if it bounces and if that bouncing gets worse as it warms up. It sounds too mechanical to be exhaust, but hard to be 100% positive. If it's valvetrain the vacuum guage will sniff it out. You should have solid stable vacuum at all engine speeds and temps, if it bounces you have a valvetrain issue (or some mechanical fault).
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#12
03-14-2011, 02:02 AM
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The vacuum gauge slowly drifts (no bouncing) from 15.5-16" at 850 rpm but thought this was because of the 110 LSA cam.
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#13
03-14-2011, 07:37 AM
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industrial sewing machine clatter is = rockers/lifters imo. you can hear it phasing with the firing before you move to the other side. How did the valve/rocker tip pattern look when you put it together?
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#14
03-14-2011, 07:48 AM
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and thoose rockers sound worse than my old porsche when it got out of adjustment , no exaust leak , it it was it more of a less metallic tick noise , check your rocker geometry your pushrods might be too short .
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#15
03-14-2011, 11:11 AM
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The rockers are stamped 1.5:1 and the cam is the 280H magnum series so I'm not too sure where these lobes fit on the scale of mild to aggressive. The engine was professionally built by a local machine shop with a very solid reputation even with the competition. It even states on the build sheet "correct valve train geometry" and this guy has been in business since the earth was cooling.
I pulled the lifters about 1000 miles ago checked the cam lobe lift as well all and both were fine making me think it might be the rockers/pushrods at fault. Could the fulcrums in the rockers be worn out making a noise like this? The cam has .480 lift and am wondering if that might be too much total lift for a tamped rocker. Thanks for the input! |
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#16
03-14-2011, 05:45 PM
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#1: Make sure you have plenty of retainer to guide clearance.
If you can isolate the rocvker. Take it out and elongate the stud hole towards the valve and repalce .If it goes away the cam lift is binding the rocker and stud. You did change the springs right? |
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#17
03-14-2011, 07:20 PM
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Dude,
What sort of retainer to guide clearance should I be looking for? The springs are Crower 68404's (shimmed to 1.605" with coil bind at 1.00") but the rocker arm kit was a Melling part number mrk-434 and can't find much info on them. Also, would there be a tell or witness mark on the stud if it is binding? |
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#18
03-15-2011, 11:40 AM
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Is anyone else having trouble hearing the audio in the video link I posted? Three people so far have said that there's no sound so maybe I'll try and just post the audio.
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#19
03-15-2011, 12:00 PM
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Quote:
If it is just touching you might not see marks. But you can elongate the holes towards the valve stem in the roker for safety sake. about 1/16" to 1/8" is fine. Also make sure each rocker is centered. I have had to adjust many a guideplate/pushrod hole to get the rocker centered on the valve tip. |
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#20
03-16-2011, 12:38 AM
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Is the video with or without the rocker covers on? If they are off it sounds normal to me.
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