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04-11-2010, 10:55 PM
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#1 |
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Registered User
Join Date: Aug 2009
Location: Red Wing Mn
Posts: 526
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Did a compression Test today
I have a 1968 chevy Lwb With a 307 that has 54,000 miles on it. I ran a compression test on it today and this is what it got.
1. 130 2. 140 3. 135 4. 150 5. 135 6. 140 7. 130 8. 140 They all started at 90 or so on the first rotation then jumped up to the numbers I posted above. One sit is lower then the other not sure if its from the battery running low or not ? Where should i go from here ? Do i need to rebuild everything or will i be ok with just gaskets and seals ? Another question. There is a hose running from the air cleaner to valve cover is that the Pcv Valve ? This is my first build so i don't know alot but i'm learning. And i know I should change it to a 350, but its a numbers matching motor so i would like to keep it. |
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04-11-2010, 11:01 PM
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#2 |
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Registered User
Join Date: Mar 2010
Location: Austin, TX
Posts: 299
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Re: Did a compression Test today
Numbers look good to me , you should have a line to the carb that has a PVC valve in it
__________________
1972 GMC Sierra LWB (Aquafresh) 1962 Cadillac Convertible 1962 Cadillac Sedan project |
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04-11-2010, 11:12 PM
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#3 |
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Registered User
Join Date: Aug 2009
Location: Red Wing Mn
Posts: 526
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Re: Did a compression Test today
What is the line running from the Air cleaner to the valve cover with a hole and a grommet. It looks like a big Pcv Valve ? I Know for a fact that I have that A.I.R emissions on my truck.
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04-12-2010, 03:04 PM
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#4 |
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Registered User
Join Date: Aug 2009
Location: Red Wing Mn
Posts: 526
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Re: Did a compression Test today
anyone else have any thoughts ?
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04-12-2010, 03:44 PM
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#5 |
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Jason
Join Date: Sep 2008
Location: Wetumpka, AL
Posts: 152
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Re: Did a compression Test today
The PCV valve will go to a full vacuum source on the carb. The Hose from the valve cover to the Air cleaner is the crank case breather.
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04-12-2010, 03:53 PM
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#6 | |
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Registered User
Join Date: Dec 2008
Location: Yay Area CA
Posts: 2,329
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Re: Did a compression Test today
X2
__________________
1965 GMC shortwide big window 1969 Chevy C20 long (for now) 2005 Silverado 2500HD Crew Cab Quote:
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04-12-2010, 04:27 PM
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#7 | |
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Gone to greener pastures
 Join Date: May 2007
Location: Gateway to the Delta
Posts: 7,354
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Re: Did a compression Test today
Quote:
In your case, 120#; so things look okay. It looks like everybody else has answered your other questions.
__________________
'69 Chevy 1/2 T LWB Stepper: Daily Beater '72 GMC 3/4 T Fleet: Another Daily Beater '72 Plymouth Gran Coupe: ? "Ah women. They make the highs higher and the lows more frequent." Friedrich Nietzsche "Never kick a fresh turd on a hot day." Harry S. Truman GUN CONTROL: Never having to say, "I missed you." Always fire two warning shots into your attacker's chest area before putting a bullet between his eyes. Paraphrased from Louis Awerbuck |
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04-12-2010, 07:54 PM
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#8 |
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Registered User
Join Date: Aug 2009
Location: Red Wing Mn
Posts: 526
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Re: Did a compression Test today
ok thanks everyone. So with my numbers looking good do you think i should just pull the motor and put in new gaskets and fresh paint. Or would you rebuild it? Which would cost me 1,500 since i have no idea what im doing when it comes to the inside of a motor. I'm leaning towards new gaskets and fresh paint. I know its what I want out of it but would like to hear other peoples opinion.
Run it and paint it or Complete rebuild ? |
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04-12-2010, 08:09 PM
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#9 |
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Registered User
Join Date: Feb 2010
Location: duluth mn
Posts: 108
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Re: Did a compression Test today
what are you trying to accomplish. your compression is fine. why would you want to pull the motor. are you having problems? no reason you shouldnt get 100k out of motor
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04-12-2010, 08:20 PM
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#10 |
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Registered User
Join Date: May 2007
Location: Southern, Saskatchewan
Posts: 640
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Re: Did a compression Test today
I would also keep the 307 as its numbers match and the compression is good. Any pics?
__________________
Kerry My build thread. http://67-72chevytrucks.com/vboard/s....php?p=3657823 1971 Chev SWB with 68 nose, 6.2 diesel th350, and 3.73 rear gears 1988 Chev Extendacab 2010 Honda VT1300CS Sabre 2005 Buick Rendezvous wife's ride |
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04-12-2010, 11:05 PM
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#11 |
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Registered User
Join Date: Aug 2009
Location: Red Wing Mn
Posts: 526
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Re: Did a compression Test today
No pictures just yet, Im going to pull it so i can clean i up and paint it as well as put new gaskets in.
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04-12-2010, 11:34 PM
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#12 |
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Registered User
Join Date: Jan 2009
Location: Queen Creek Arizona
Posts: 56
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Re: Did a compression Test today
When you took the comp. test did you remove all the plugs before you started? the engine will spin over much easier and give you the full reading faster. If you plan on dressing up under the hood like painting the fender wells, fire wall and such pulling the engine for gaskets and paint job would be fine, if it is leaking oil or if you suspect the timing chain and gears are getting on the loose side you may want to pull it and fix them, if you pull the pan do not neglect the oil pump, cheap and easy to replace on the stand. Good luck and have fun.
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04-12-2010, 11:37 PM
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#13 |
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Registered User
Join Date: Jul 2006
Location: Central PA
Posts: 12,201
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Re: Did a compression Test today
make sure you don't have any leaks and run it... unless you are building a show truck. If you have oil leaks then fix those seals while it's inthe truck and then run it...
__________________
The Garage: 1968 K-10 SWB - "Project Money Pit" 1996 Z-71 - "huntin rig" 1969 C-10 LWB (SOLD) "Project flip that truck or else" 1993 Passport, F@rd 1-ton (SOLD)"Project Cousin Eddie" My Garage Build "The 1,000 footer" Last edited by msgross; 04-12-2010 at 11:38 PM. |
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04-13-2010, 03:09 AM
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#14 |
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Registered User
Join Date: Jul 2007
Location: Salina, Kansas
Posts: 1,998
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Re: Did a compression Test today
from my class i took.. 90 is the base anything below 90 its time to rebuild.. guys does that sound right? but like stated here.. your good
__________________
1972 C-10...402/400..flowmaster 40 series 1967 Mustang 347 stroker/C-4 1966 Mustang 289/3-speed 2013 Mustang V6/6speed w/300 ponies I may be 23, but i sure do knows 67-72s are sexy! Its not MPG its smiles per gallon! build started 11/25/08 build thread: http://67-72chevytrucks.com/vboard/s....php?p=2993796 |
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04-13-2010, 08:46 AM
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#15 |
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Registered User
Join Date: Aug 2009
Location: Red Wing Mn
Posts: 526
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Re: Did a compression Test today
I only did one plug at a time - when i did my compression test. Thanks for the advice on the oil pump. I plan on taking the oil pan off an putting a new gasket there too.
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04-13-2010, 08:49 AM
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#16 |
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Registered User
Join Date: Aug 2009
Location: Red Wing Mn
Posts: 526
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Re: Did a compression Test today
Not sure about the timing chain the truck only has 54,000 on it do you think i would have too?
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04-13-2010, 08:52 AM
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#17 |
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Between Trucks...
Join Date: Mar 2002
Location: Los Angeles, CA.
Posts: 3,830
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Re: Did a compression Test today
If you're going to pull the motor anyway, might as well do the timing chain and oil pump. Get a double roller timing set.
__________________
Beat it to fit, Paint it to match... 
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