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10-21-2011, 06:54 PM
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#1 |
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Registered User
Join Date: Aug 2011
Location: Cairo, Nebraska
Posts: 56
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Unknown Noises
Hello, I have a question about my 68 K10 with a 327. When you mat it and the 4-barrel opens and you get around 5 grand and up there is a crackling noise. It sounds like it is coming from the carb. It still has great power when it does this, and it will keep winding till ruffly 6 1/2 to 7 grand (didn't want to blow it up). Anyone know what this could be?
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1968 Chevy K10 56,000 miles 
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10-23-2011, 07:06 PM
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#2 |
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Registered User
Join Date: Oct 2011
Location: olympia washington
Posts: 63
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Re: Unknown Noises
are you in park while it makes that noise at 5000 or driving it? if its doing it while driving at that rpm it could maybe be a spark knock with means your ignition timing is to far advanced or its not a high enoyfe octain fuel. try putting in premium gas if u dont already or retard the timing about 1 or 2 degress at a time and see if it helps.
also just a word of advice your engine need 1psi of oil pressure for every 100 rpm so if you hitting 7000 just make sure you have around 70psi of oil pressure. hope this helps out 
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Josh 1970 custom camper 20 longhorn 1970 ford f250 highboy |
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10-23-2011, 10:16 PM
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#3 |
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Grandpa in the rustmobile...
Join Date: Nov 2008
Location: Spokane WA/Viola TN
Posts: 11,422
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Re: Unknown Noises
dang what kinda bottom end do ya got to spin er till 7k?
does it sound like it 'pings'?
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John Goose-1968 C10 355,9.32-1CR, Vortec Heads ,262 voodoo, 3.73:1 3OTT (HS ride/beater/farm truck) http://67-72chevytrucks.com/vboard/s...d.php?t=317684 Grams 53-1953 Chevrolet Belair http://67-72chevytrucks.com/vboard/s...=1#post4327784 1969 Chevy C10 Shortbed 4.5/6?" Frame off resto http://67-72chevytrucks.com/vboard/s...d.php?t=548136 1999 Toyota Tacoma 4x4 |
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10-24-2011, 03:56 PM
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#4 |
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Registered User
Join Date: Aug 2011
Location: Cairo, Nebraska
Posts: 56
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Re: Unknown Noises
No it is just a stock 327, with maybe a different cam in it. It only has 54,xxx miles on it with a 6,xxx mile rebuild on it. It is when i am driving, it is also not a "pinging" noise ether. We messed with the timing to and that didn't help.
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1968 Chevy K10 56,000 miles
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10-24-2011, 04:10 PM
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#5 |
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Registered User
 Join Date: Nov 2007
Location: Hermiston, OR
Posts: 947
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Re: Unknown Noises
Did you upgrade vavlesprings? My guess would be valve float.
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Running in place gets you nowhere fast. -me 1968 GTO 4-spd covnvertible 1970 K-20 4-speed, factory AC. |
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10-24-2011, 04:29 PM
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#6 | |
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Registered User
Join Date: Sep 2011
Location: Hattiesburg, Ms
Posts: 65
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Re: Unknown Noises
Quote:
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10-24-2011, 04:48 PM
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#7 | ||||
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"I ain't nobody, dork."
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,971
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Re: Unknown Noises
Exactly... Stock 327 above 5,000K = bad juju.
Gary
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'cuz chicks dig scars... My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread. The Rebuild of Creeping Death after the wreck Quote:
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10-24-2011, 05:09 PM
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#8 |
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Registered User
Join Date: Feb 2003
Location: Santa Ana, CA
Posts: 2,191
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Re: Unknown Noises
x3 on valve float. I would be very careful turning those kinds of RPMs with the stock valve springs and rocker arms. The stock rocker arms like to rotate off of the springs and push rods if not adjusted just right due to shallow retaining indents. Pushing those RPMs can definitely aggravate that situation leading to bent push rods, broken rocker arms, and alot of carb backfiring. As me how I know....
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10-24-2011, 05:29 PM
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#9 |
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Old Skool Club
Join Date: Jun 2001
Location: Benton, AR "The Heart of Arkansas"
Posts: 10,880
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Re: Unknown Noises
WHY are you winding it like that? Do you have a death wish for the engine and yourself? Where are you reading those R's? What kind of tach do you have?
I have had SOHC and DOHC engines and didn't wind 'em up like that. My '67 Firebird Sprint had a 230 SOHC 6-cylinder and it sounded real good but never had any desire to take it over 5-grand....didn't need to.
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Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was. |
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10-24-2011, 05:37 PM
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#10 |
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Registered User
Join Date: Nov 2007
Location: Hermiston, OR
Posts: 947
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Re: Unknown Noises
not to mention, if it is even a mild street perf cam you are running WAY past peak HP.
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Running in place gets you nowhere fast. -me 1968 GTO 4-spd covnvertible 1970 K-20 4-speed, factory AC. |
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10-24-2011, 05:46 PM
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#11 |
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its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,690
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Re: Unknown Noises
if he's done this more than a few times, then I doubt his tach is right.
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10-24-2011, 09:19 PM
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#12 |
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Registered User
Join Date: Aug 2011
Location: Cairo, Nebraska
Posts: 56
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Re: Unknown Noises
I don't know for sure that it was 6 1/2k or not I'm just guessing, I don't got a tach in my truck. Also I just did it once, and it was it 2nd gear so I wound so quickly. It wasn't up there for very long with the short stroke.
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1968 Chevy K10 56,000 miles
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