Compression=not good

[eclpsegsx12]

I have a 98 gsx and i recently did a 1g head swap. Before that though i blew the head gasket once with the 2g head, got that o-ringed, new stock HG and ARP's...then i blew the HG a 2nd time, got a really nice 1g head and swapped it out and used a cometic 4 layer metal HP HG....we started it up and the guy who set my timing set it off 1-2 teeth so my timing was really messed up and it wouldnt idle worth shit. Then yesterday a buddy of mine and i reset the T-belt right on. Its 5 degrees timing and is perfect. Before we reset the timing we did a compression test and it read this from 1-4:150,88,150,180....that scared me a little...then when we were done, we started it up and it purred....did another compression test and its the same. Im just wondering what this could be. Im still going to be driving it this summer until next year when i build the 6-bolt. Any help would be greatly appreciated. Thanks

 

[Doug99RS]

Did you have a machine shop look at the cylinder head you put on? You could have picked up a head with a burned valve or that was warped. Does the exhaust have a lope to it? Frequently a bent or burned valve will cause a lope to develope in the exhaust.
Doug

 

[eclpsegsx12]

nope, no lope....and i didnt get it checked at the machine shop...a few buddies had it and it looked awesome like it was just rebuilt....its probably somewhere in the valvetrain but im not positive

 

[boostnbuds]

"If the gauge pumps up slowly, such as 30, 50, 70, 90, etc. to an almost normal reading, you probably have ring problems. A general rule is that a maximum reading should occur after two strokes. If oil is added to a low reading and the pressure improves, this will confirm worn rings. A persistent low reading generally indicates valve problems.

Oil lost through worn valve guides will not be determined through compression testing. Low readings can also be caused by a warped head and occasionally, two cylinders will have very low compression which can be the result of a blown head gasket. It is important to remember that the addition of oil to the combustion chamber will not improve the compression readings if your engine has burned, warped or stuck valves. High compression readings can be the result of carbon buildup or head surfacing."
http://www.georgiazclub.com/tips/ztech/comptest.htm:thumb:

 

[Doug99RS]

What he said

 

[eclpsegsx12]

Well thanks a ton!......We did put a little oil down the cylinder to see if it would seal the rings if it was a ring problem and it only increased the PSI to 90 on number 2....

 

[RoasT BeeF]

Do a leakdown test to find out exactly where you are loosing compression.