I'm in the starting stages of building my 350 (tear down next week)
so far we (the engine builder and I) have decided that we will:
1. bore it out, 355, use a 9.3:1 rebuild
2. use a set of 58 cc Ho heads, and probably cut the valves out to 1.94s
3. the cam has about (don't have the card infront of me) 489 lift and 190 dur.

he thinks that this will give me 10.5:1 compression and another friend thinks that should boost my hp big time

any thoughts?

 

i think you ought to do the math and you'd know exactily what your compression is. it'd help us all guess at any HP increase if you'd post what your HP is now.

 

High compression isn't the be-all, end-all of making power. Generally accpeted wisdom is that 1 point of compression is worth about 4% power (about 12HP on a 300HP engine). It will feel like more than that since it will bump up low-midrange torque even more.

For a street engine that will see a regular diet of pump gas it's better to stay a little conservative than to live on the "bleeding edge" of detonation.

If you have the choice between lower compression but the ability to advance the spark to it's optimum power-making point OR higher compression but needing to back the spark off to stay out of detonation ALWAYS go with lower compression but full spark advance. It will make more power.