Blow by and running hot! sounds to me like you need new rings. Your compression rings are probably cracked for sure. I have done what you did and been down this road with many motors. Put rings in the car and add a converter for that cam you installed and your done. Putting your 318 heads back on will make it worse. you will have less to compress. The cam made your tired motor lose power because, as someone else stated you lost cranking pressure from overlap. I have installed 360 top ends on 318's and they ran strong and created alot of torque. 318 has a lighter recipricating wieght. If you don't have the compression for your cam choice it will not work effectively. Blow by say's no compression. you are making a bad choice worse by putting your heads back on. You will need an intake for 318 heads, You cannot put 360 ports running into 318 ports. You will great a step in the direction of the flow this will open up a new and worse problem for you. Early intakes for small blocks were different for 318 V's 340 360, The 318 was a LD4B, 340 360 was a LD340. You can install a LD4B on a 340 but you can't use the Ld340 on a 318. So what I am saying is you can go from a smaller intake port to a larger head port. But you cannot go from a large intake to a small head. It would be like hitting the curb or driving off of one. what would you think would be the result. Its a common sense No Brainer.
