305 problem

hey evryone i have an s10 i am putting yet another 305 in it , i have the motor in and it starts, at idle it sounds great , but as soon as you give it some gas there is a wierd (tick) backfire comin out the carb. the timing is on for sure and there is spark in all cylinders replaced fuel pump and plugs and about to change distributer is there any other ideas out there of what could be the problem??
please i need ur help!
thanks alot
Paul

hey evryone i have an s10 i am putting yet another 305 in it , i have the motor in and it starts, at idle it sounds great , but as soon as you give it some gas there is a wierd (tick) backfire comin out the carb. the timing is on for sure and there is spark in all cylinders replaced fuel pump and plugs and about to change distributer is there any other ideas out there of what could be the problem??
please i need ur help!
thanks alot
PaulSounds like they may be a lob wore off the cam shaft or timeing may be to low .Turn your dist torwards the driver side fire wall,wich is counter clock wise to bump up visa versa to lower which if back firing you need to advance up and adjust by ear.

Sticking intake valve? Weak spring on an intake that won't allow the valve to seat at higher RPM's? Cracked valve seat? Have you done a compression check?