Won't start, stumped.

[DjPantsSpecR]

i want to be as specific as possible, because i have been working at this in below zero weather for four days now. its a 92 240sx, and this one is an automatic. It was a perfectly running car, so i decided that i wanted to swap in an exhaust cam for the intake cam, and i know to rotate it back four teeth, etc. I couldnt get it to fire so i put everything back to stock. i've tried many many different ways to time the cams, and right now the cam timing appears to be spot on, to make sure i even rebuilt my other 240 with identical distributer timing and cam timing, and it fired on the first try. all mine will do is crank, the best it can do is pop, but it wont fire. i've swapped distributers, maf, plug wires. there is spark, fuel, and like i said the set up is identical to my other 240 which fired up immediately. i checked for bent valves, and all the clearance between the cam and the shims is within spec (.012). but still the compression doesnt seem the same as the other 240, and you cant hear the air blow by the rings when you pull it through the strokes by hand. i'm stumped and i need this car to work by tuesday

[s13sr20chris]

possible that you flooded it with all the attempts. try drying the plugs and the cyls. i would do a compression test if that does not work. also, take a vacuum reading while trying to start.

[DjPantsSpecR]

i've tried drying the plugs, but a more thorough job could be done, im not sure as how to dry out the cyls other than pulling fuel pump fuse, pulluing the injector wires and cranking it a bunch, how wold you do it? i'm confused about where i should take this vacuum reading from. unfortunately i have not sourced a compression tester either. i have been trying my darndest to get this car to start for five days and im stumped, and i need it to run on tuesday. thanks alot chris, i knew you would read this and help soon enough, you helped me out before with my other 240sx

[s13sr20chris]

i hate to say it but i am worried about your valves. its the most likely thing after the cam swap.