240z engine miss.

[tigerjoel240z]

72 240z just rebuilt have not been able to find out why engine mis,at low and high speeds! seems to run just fine other wise.The engine is stock except for exhaust valve and intake are bigger!I have replaced cap ,rotor ,plugs,wires,cleaned carbs,and checked timing!I give up! Its fast except for it miss at and all other speeds! Gets worse when it is all warmed up! please help me!

[evildky]

have you checke dthe plugs? I suspect taht the miss is constant but the harmonic's of the mid range make it undetectable, you said you have oversized valves, did you swap heads of just put oversized valves in an e series head? if you swapped valves, did you have the work done at a reputable machine shop? have you checked you're valve stem seals? a lot of the aftermarket seals seam to be problems

also what carbs are you running? and did it run fine before the valve job? ever had your gas tank cleaned? could be an intermitant fuel starvation, also you clean the fuel bowls?