I have an 87 iroc that originally had a 305 carborated motor, we put a 350 worked carborated motor in it which ran fine, now we are selling the car so we took out the 350 and put in a newly rebuilt 305 (not the orginal 305). We got the car to fire once drove it down the road but didnt quite have everything hooked up yet so shut it off and finished hooking things up. then the car had a hard time starting and fire one more time ran for a few moments and shut off. Now it will not start. Car has an HEI distributor and we have low spark. Replaced the cap, rotor, plugs, new battery, new positive cable, coil, and terminal module. Still low spark and car will not start

 

is it getting the fuel for sure?

 

yes it is getting fuel

 

Plugs look fine?
That happened to me recently..fouled the plugs after driving three miles..

 

after it started the once and then wouldnt start again, we relized it was getting low spark. so we did put new plugs in.

 

reverify your voltage & grnd at the distributor.

 

i would say ground. or a coil