GM Engine & Exhaust Performance EFI | GEN I/GEN II/GEN III/GEN IV Engines |Small Block | Big Block |

compression check?

Thread Tools
 
Search this Thread
 
Old Mar 10, 2003 | 10:44 PM
  #1  
RED2K's Avatar
Thread Starter
TECH Addict
 
Joined: Jul 2002
Posts: 2,708
Likes: 0
From: fayetteville AR
Default compression check?

What should each cylinder read when i do this?
Reply
Old Mar 10, 2003 | 11:14 PM
  #2  
TECH Junkie
 
Joined: Mar 2002
Posts: 3,019
Likes: 1
From: memphis tn
Default Re: compression check?

You will lose some static compression with a cam change. With the increase in lift and duration the engine can't make as much cylinder pressure.You do get a side benifit that your octane requirements for the engine are reduced.Check for big differences in compression between cylinders if the high and low cylinders are within 10 to 15 percent you are ok.
Reply
Old Mar 13, 2003 | 07:01 PM
  #3  
RED2K's Avatar
Thread Starter
TECH Addict
 
Joined: Jul 2002
Posts: 2,708
Likes: 0
From: fayetteville AR
Default Re: compression check?

ttt
Reply
Old Mar 13, 2003 | 07:15 PM
  #4  
really slow truck's Avatar
TECH Fanatic
 
Joined: Nov 2001
Posts: 1,410
Likes: 0
From: north dallas
Default Re: compression check?

like he said they should all be somewhere within around 10-15% of each other. i cant remember what mine read when i checked it a while back tho <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Reply
Old Mar 13, 2003 | 07:39 PM
  #5  
BigTex's Avatar
? ? ? ? ? ?
iTrader: (16)
 
Joined: Nov 2001
Posts: 7,126
Likes: 2
From: East of Dallas
Default Re: compression check?

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by really slow truck:
<strong> like he said they should all be somewhere within around 10-15% of each other. i cant remember what mine read when i checked it a while back tho <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">What does yours read right now? <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
Reply
Old Mar 13, 2003 | 08:10 PM
  #6  
really slow truck's Avatar
TECH Fanatic
 
Joined: Nov 2001
Posts: 1,410
Likes: 0
From: north dallas
Default Re: compression check?

well, i screwed in the pressure gauage, turned the engine over a few times to see what it read for good ol' red2k... kept getting readings of zero <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

but then i was thinkin, doesnt it work better when the head is attached to the block? <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

<small>[ March 13, 2003, 08:15 PM: Message edited by: really slow truck ]</small>
Reply
Old Mar 13, 2003 | 10:56 PM
  #7  
RED2K's Avatar
Thread Starter
TECH Addict
 
Joined: Jul 2002
Posts: 2,708
Likes: 0
From: fayetteville AR
Default Re: compression check?

REally slow= you ***** <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> .. Man that is what i exactly what i am wanting to find out. What psi should they read?
Reply
Old Mar 14, 2003 | 11:20 AM
  #8  
really slow truck's Avatar
TECH Fanatic
 
Joined: Nov 2001
Posts: 1,410
Likes: 0
From: north dallas
Default Re: compression check?

what are yours reading?
Reply
Old Mar 14, 2003 | 01:06 PM
  #9  
Neil 6.0's Avatar
TECH Addict
 
Joined: Nov 2001
Posts: 2,205
Likes: 0
From: as far away from Koonerville as humanly possible
Default Re: compression check?

I would have to guess somewhere around 125-to-150psi to be the norm. I think that as long as it is over 100psi that it is within GM's specs.
Reply
Old Mar 14, 2003 | 01:18 PM
  #10  
L82gofast's Avatar
TECH Regular
iTrader: (1)
 
Joined: Jun 2002
Posts: 491
Likes: 0
From: Oatmeal, TX
Default Re: compression check?

Yep, Neil is right. The GM spec in the service manual just says 100psi - minimum.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
walledition
GM Drivetrain & Suspension
45
Feb 24, 2026 03:27 PM
zblee
GM Engine & Exhaust Performance
3
Nov 11, 2015 12:41 AM
Tydriver
GM Engine & Exhaust Performance
45
Oct 23, 2015 09:19 PM
Boyes50
FUEL SYSTEMS
2
Sep 8, 2015 12:06 PM
bisqikss
GM Engine & Exhaust Performance
15
Sep 8, 2015 03:35 AM




All times are GMT -5. The time now is 04:25 PM.