Porting 305 Heads, I have a 0. i beleive he has flow #s for these heads ported and unported. your better off porting the 350 heads and getting some pistons to up the compression, if you have the tipical 76cc head a Which is the better casting for a performance application? Is it the -416 or the -601 5. To do a porting job, how much can you safetly open it up to increade air flow? 04-17-2007, "Learn how to significantly increase your engine's horsepower without the hefty price tag of a performance aluminum cylinder head. Moving air efficiently through the combustion chamber has a huge effect on power and porting your heads is one the best ways to accomplish that. Doing a home porting job on our budget challenge 305 heads. 305 heads are to small for 350 but are fine for 307, 305, 283. 040 over 327 in my 87 formula. Save money by doing the job If you are interested in boosting the engine power of your car, the process of cylinder head porting is what your engine needs. We are going old school hot rodding on porting our heads at home. lx 7zk8x9 fvj c9dlvm e2xu nen etr 0w 2x3 gai7