i got an ls motor in pieces. I put it all back together and have it on an engine stand. no intake or exhaust mani but everything else is there. for some stupid *** reason i can't get any compression. they are 20-0-30-0. it makes no sense to me cause if the head was warped compression shouldn't skip a cylinder. the head gasket is brand new and was torqued down to 63 pounds like it is supposed to be. the valves are all adjusted to spec. i don't get it please help.

 

You 110% sure the cam timing is correct?

Also, when compression testing a motor it should be at operating temperature...so I'm not sure how good of numbers you can get from a cold motor that was just put together.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sporkcrx &raquo;</TD></TR><TR><TD CLASS="quote">You 110% sure the cam timing is correct?

Also, when compression testing a motor it should be at operating temperature...so I'm not sure how good of numbers you can get from a cold motor that was just put together.</TD></TR></TABLE>
yes the white mark is dead on with the plastic arrow.
that is what we where thinking about the compression numbers. and we tried it on another ls that has blown rings in 2 cylanders and it got to around 120. so it should be able to go a little higher than 30 right?

 

crank AND cam timing being correct....I would have no clue. Maybe because the rings need to seat or something.

 

It's probably the cam timing.

Double check with the manual and make sure EVERY mark is the correct one.

I made a similar mistake once; I used the wrong marks to set the cam timing, and it wouldn't crank and it had bad compression in a few cylinders. I fixed the timing, and it started up like a charm!

 

How are you turning the crank? and are you tirning the engine the correct way?
Other than that as said check the cam timing

 

you're using the starter right? cuz by hand i doubt that you get anything high....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GZERO &raquo;</TD></TR><TR><TD CLASS="quote">you're using the starter right? cuz by hand i doubt that you get anything high....</TD></TR></TABLE>

Good point! You will need to use the starter to get an accurate reading; turning by hand just won't keep enough compression in the cylinder during the power stroke.

 

try doing a leak down test

 

yes try doing a leak down test and see if it holds. If it doesn't hold the only thing it could be is the cam timing or the piston rings.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjohnson329 &raquo;</TD></TR><TR><TD CLASS="quote">yes try doing a leak down test and see if it holds. If it doesn't hold the only thing it could be is the cam timing or the piston rings.</TD></TR></TABLE>

or bent/misadjusted valves. Why was it in peces in the first place?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjbizzo &raquo;</TD></TR><TR><TD CLASS="quote">

or bent/misadjusted valves. Why was it in peces in the first place? </TD></TR></TABLE>
i don't know the guy i bought it frome took it apart.

i got new problems now. i got it all working and installed into my crx. it idles but you cant rev it. there is like 3 vacume lines that have to be capped off because there is no use for them but i'm either missing one or something. i'm guessing that it is the intake mani gasket. if it is not sealed right it will run like *** right? once you get the rpms past 3k it runs allright. is it the gasket?