Causes of bad compression on my 93 240sx vert? Help Please!

[mrk442]

I have a 93 Vert that i toasted the motor in.

I bought a supposedly strong running under 100k motor.. well it had a blown head gasket and pressurized my cooling system to the point of blasting out the overflow the first time i turned it over.. I pulled the head and used my strait edge to check the block and head.. both within specs.. So i slapped on a new head gasket and tried to start it up.. no start.. I check the compression and they are all sitting around 50psi.....

Its possible the head was warped more then I thought but i checked length wise.. width wise. cross wise and every other way i could think of and besides even a warped head should seal for a little while right?

so i am left to wonder whats my problem..

valves leaking? how can i check the valve seats i have heard you can pore acetone in the valves and check for leaks but i thought that was with the head off? any way to check with the head on since i don't want to buy new head bolts?

is it possible i got the cams back on a little wrong and they are staying open into the compression stroke?how would i check this?

anything else?

little help would be great before i pull the damn egnine again and find anouther.....

[driftingmy240sx]

sounds like your mechanical timing is off. cams out of position will cause low compression.

to check set cylinder one to top dead center on compression strok and with the valve cover removed make sure the cyl 1 cam lobes face away from each other (like this <o o> ). also make sure the distributor rotor is pointing at the cyl 1 spot on the cap.

[mrk442]

But how does one go about checking cam timing?

[driftingmy240sx]

set the crank at tdc for cyl one and make sure the cam lobes face away from each other on cyl 1 is a very easy visual check like said in my previous quote. what did you use to set the mechnical timing when you put the head back on? did you have a chain alignment diagram?