Low Compression, not starting?

[silslider13]

Alright, i have a 1990 240SX fastback, and the previous owner blew the head gasket, so i replaced that, and this guy that i know decided he would get me a new head as well, so i let him do that. He assembled everything and he said that it gets low compression now, and it doesnt start. What could cause this, he said he thinks its cuz the valves are new and they might not be seading properly? I dont know, so i was just curious what you guys thought the problem could be. Thanks in advance!

[steve s14]

new valves should seal well if it is installed properly. my guess is that the timing chain is not timed correctly and it is of by a tooth or more. do a leak down test and if that shows there is leaking from the valves, double check the chain timing.

[silslider13]

Alright, i will do that stuff, if it is timed right should all cylinders be getting about the same compression, i have no idea about this stuff, im new to all this stuff, the guy thats working on my car wants it, so i dont know if he timed it wrong on purpose thinking i would just give it to him or what, so i dont know, i will talk to him about it when i get the chance. Thanks guys!

[benemorius]

I would highly recommend a leakdown test.