i have a 350 in one of my cars that has 305 heads on it(that is the way i got it). and i was wondering if that could be causing the severe blowby that it is having. It looks as though the motor has just been rebuilt so i don't think anything is worn out, i think it just has too much compression. what, if anything, can i do to solve some of the blowby, without swapping heads. This setup runs awesome so i don't want to change it too much. This motor runs real smooth with no noticable cam and ran a 9.6 at the track spinning, but i have no idea what internals it has. the head casting # is 14014416 and the block casting # is 3970010.
any help would be great.

 

Heads wouldn't cause blowby. Blowby is either rings or gaskets. It's not unusual for people not to retorque head gaskets these days because the gaskets say "no retorque". It's a lie. My nephew put aluminum heads on his 350. I told him to retorque, he didn't, gasket on passenger side failed. When he took it apart he was shocked at how loose the bolts were. So he had to do it again. Intake manifolds also get loose.

 

well the oil breather was stoped up and when you take the pvc valve out of the valve cover, a whole bunch of smoke is shooting out. and if you get on the car really hard oil comes out of the dipstick tube, the cheapo guage says the car only has about 50psi when you get on it, so either the guage is wrong or the compression is pushing oil out of the dipstick tube since the breather was stoped up and the pvc valve couldnt keep up.