Compression spec

**topherC5** · 04-18-2012, 04:33 PM

Hi guys, Does anyone have a quick spec on compression checks? 150-160 ??? 2000 LS1

**pajeff02** · 04-18-2012, 06:46 PM

Honestly, I have never looked at the spec. I can check my service manual in the a.m. if no one else chimes in.

BTW -- welcome to the site!

**topherC5** · 04-18-2012, 08:10 PM

Thanks Jeff... The only LS manual I have is for the 5.3 and it might be the same but I'm not sure. Just wanted to post and chat up the site some while I am here looking around.

**pajeff02** · 04-19-2012, 03:26 AM

My 2002 manual lists the cylinder compression for an F-body as 10.1:1 and for a Y-body as 10.5:1. Unfortunately, I was not able to locate the compression figures in p.s.i. -- the index is not the best and I resorted to scanning pages in areas of the manual that I thought it might be listed. I will check again this evening.

**topherC5** · 04-20-2012, 04:33 PM

Ok Jeff thanks for checking...

**pajeff02** · 04-22-2012, 04:54 PM

Struck out -- found the section of the manual that details compression testing the engine, but there is no spec provided. They simply give the standard "within 10% of one another" and tell you how to perform the test. I also read through all the specs in the introductory tables and nothing there either.

**35th-ANV-SS** · 04-22-2012, 05:41 PM

I read somewhere else that it shouldn't be below 100...and no cylinder should be less than 70% of the highest cylinder reading.

**pajeff02** · 04-22-2012, 05:51 PM

^^ That sounds like about what I read in the testing procedure. I want to say that a healthy engine should have at least 180 psi, but I have nothing to reference that to.

**35th-ANV-SS** · 04-22-2012, 07:05 PM

Yea I've seen them range pretty widely over the years. Some are around 220 and others as low as 120. Also depends on whether it is a dry test or wet. Could have been because of different heads/cam too though. I believe the above is from a stock 98 LS1, which would be similar to a 2000.

**pajeff02** · 04-23-2012, 03:11 AM

FWIW, the test procedure is fully charge the battery, disable both the ignition and fuel systems (pull fuses or relays), remove all 8 spark plugs, block the throttle plate wide open, and turn the engine over 4 times for each cylinder. If you get a low reading, you can go back and put a small amount of oil into that cylinder through the plug hole and then re-test it. That will dilineate between rings (cylinder pressure will go up) versus valves or head gasket (pressure will remain essentially the same).

**topherC5** · 04-24-2012, 03:11 PM

Sounds like all good info to me. The key is all 8 cyl. should be pretty close in pressure. I had a slight puff of smoke at start up and think it might be valve seals... Thanks for the help guys!