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02-15-2006, 11:13 AM
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#1 |
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Registered User
Join Date: Dec 2005
Location: delaware
Posts: 26
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Compression tests???????
Finally home from Kuwait and did a compression test on the 307...
I have read different theories on compression tests and am looking for some input. I used a new craftsman screw in gauge, took all the plugs out and left choke open for more air. -no oil in cylinders- I got 155-165 in all. Does anybody know what these motors had when they were new? How bad is 155 on that motor? Thanks for the input! The 1947 - 1998 Chevrolet & GMC Pickup Message Board Network > 47 - Current classic GM Trucks > The 1967-1972 Chevrolet & GMC Pickups Message Board Post New Thread Welcome, mark69k20. You last visited: Today at 09:50 AM Private Messages: Unread 0, Total 2. User CP FAQ Members List Calendar vBRadio Help Desk Subscribe Board Merchandise New Posts Search Quick Links Log Out Search Forums Advanced Search Quick Links New Posts Mark Forums Read Open Buddy List User Control Panel Edit Signature Edit Avatar Edit Profile Edit Options Miscellaneous Private Messages Subscribed Threads My Profile Who's Online Forum: The 1967-1972 Chevrolet & GMC Pickups Message Board Post New Thread |
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02-15-2006, 10:30 PM
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#2 |
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What's that funky smell?
Join Date: Mar 2005
Location: Austin, TX
Posts: 610
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Re: Compression tests???????
I have been hoping for a more specific answer, too. My Haynes manual only lists 150psi, with 20psi max variation between cylinders, for V6 and V8 engines. Nothing specific for each displacement size.
I have original shop service manuals from 68 that I bought off of Ebay. The only note about compression is the same thing. 150psi w/ 20psi variation.
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Mike S 68 C10 Long Step (Pretending to be a Long Fleetside) Grandpa's Farm Truck 3 on the tree, 307, No power brakes or steering Factory Options - HD rear spring and Ammeter/Oil Gauges My truck blog My Car Domain page Last edited by TruckinDaddy; 02-15-2006 at 11:35 PM. |
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02-15-2006, 11:28 PM
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#3 |
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what happened to flint mi
Join Date: Oct 2005
Location: san diego
Posts: 437
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Re: Compression tests???????
you have a higher compression rate from carbon build up , sea foam could help .
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02-16-2006, 12:40 AM
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#4 |
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Senior Member
 
Join Date: Jul 2004
Location: Estherville, Iowa
Posts: 3,371
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Re: Compression tests???????
That looks about right for a stock 307, but the main thing to look for is a big variation between cylinders. 10 psi differnce is pretty good.
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1968 C10 307 3spd Long Fleet ------ http://67-72chevytrucks.com/vboard/s...d.php?t=201103 1970 C10 305 Super T10 Long Fleet --- http://67-72chevytrucks.com/vboard/s...d.php?t=202285 1971 C20 383 TH350 Dana Posi ----- http://67-72chevytrucks.com/vboard/s...d.php?t=206894 2001 GMC Sierra 1500 C3 6.0 |
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02-16-2006, 01:40 AM
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#5 |
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Registered User
Join Date: Jun 2002
Location: Knoxville Tenn.
Posts: 3,058
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Re: Compression tests???????
You are still in good shape those readings.
__________________
56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer |
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02-16-2006, 10:49 AM
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#6 |
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Registered User
Join Date: Apr 2004
Location: South Texas....the Valley
Posts: 199
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Re: Compression tests???????
You are good to go with those numbers. As stated: The concern is the difference between the readings.
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02-16-2006, 05:43 PM
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#7 |
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Dork For Days
Join Date: Aug 2005
Location: Dallas
Posts: 407
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Re: Compression tests???????
Sounds like good numbers for an 87-89 octane capable engine. Good variation. No worries!
__________________
1972 C20, 402/700R4 - My first classic truck, bought in September 2005. 85% transformed from "Farm" to "Cool" status! 1970 Dodge Challenger 440, 4sp (my other toy) 12.67 @ 117 MPH, with a pathetic 2.022 60' 2007 Dodge Charger SRT-8 2008 Cadillac CTS All-American garage, baby! |
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02-16-2006, 06:55 PM
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#8 |
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Fabricate till you "puke"
Join Date: Jun 2002
Location: Ill
Posts: 9,403
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Re: Compression tests???????
You are "good to go".....a fresh 327(+ 040 on the bore, with Fuelie heads & a mild cam) was 160-170 psi. Man did that F...er run good!
 L
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69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... |
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