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05-26-2012, 05:41 PM
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#1 |
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Registered User
Join Date: Aug 2009
Location: Toronto, Ontario
Posts: 111
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Compression Test
The Haynes manual suggest the cylinder compression should be around 150psi, mine is running consistany at 180psi. Would this be an indication of some sort of head work or is a 180psi still within the norm?
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05-26-2012, 05:43 PM
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#2 |
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Registered User
Join Date: Aug 2009
Location: Toronto, Ontario
Posts: 111
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Re: Compression Test
Sorry forgot to add it's a 350
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05-26-2012, 06:09 PM
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#3 |
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Registered User
Join Date: Dec 2011
Location: Arlington WA
Posts: 1,728
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Re: Compression Test
previous owner may have put higher compression pistons in it. different pattern cams can also increase/decrease presure
__________________
GMC C15 355 SM465 3.73 80 C10 cruiser build thread 79 short stepside crew cab. big and ugly. build thread |
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05-26-2012, 09:02 PM
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#4 |
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Registered User
Join Date: May 2012
Location: Visalia CA
Posts: 118
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Re: Compression Test
Could be as stated higher comp pistons or rings or head work.. If it drives fine on unleaded fuel, more comp is free hp, giving it dosent knock or ping or diesel.
Most likely, recent valve job. But all is true what ppl said if it runs fine, leave it. Posted via Mobile Device |
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05-26-2012, 09:26 PM
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#5 |
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Registered User
Join Date: Aug 2009
Location: Toronto, Ontario
Posts: 111
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Re: Compression Test
From the outside it has an edelbrock carb and intake plus a set of headers that the po installed. I have no idea what work has been done on the inside. Ive search up down for some serial number on the block and the heads but so far no luck. I do know it has a pretty rough/ aggressive ideal and when you lay on the gas she will dig holes into the ground with all four tires when in 4X4
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05-27-2012, 10:13 AM
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#6 |
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Moderator
 
Join Date: Oct 2008
Location: Wentworth, NH
Posts: 4,977
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Re: Compression Test
It's more important to have consistent compression across all 8 than the exact value. Within reason... 220 would be real high and 100 would be real low.
If it runs OK on pump gas you're good to go.
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05-27-2012, 10:30 AM
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#7 |
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Registered User
Join Date: Aug 2009
Location: Toronto, Ontario
Posts: 111
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Re: Compression Test
First Compresion stroke hits about 165 then builds up to about 176 to 185 after 4 strokes. I bought the truck about 3years ago and it has sat eversince due to me being overseas. I bought it on a whim and never had a chance to work on it or check anything before. So far I happy that at least the engine seems to be in good shape, but there are lots of other issues with it that keeping me busy and dirty
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