i have stage 1 heads, 3 angle valve job, cleaned up runners, port matched and bowl blended, but i didn't blend in the valve guides. (lack of knowledge at the time) could i see a H.P. GAIN if i do this when i update from my 113a cam to 290-08H and am i loosing power now?
Kelly The valve guide boss blocks air from flowing directly to the valve and must flow around it on the intake side. On the exhaust side, the exhaust gases rush past the valve after it opens and runs slap into the valve guide boss. It's a real good idea to cut this down and blend but you may want to use metal tape or something to protect the valve seat as chances of nicking up the surface are high. Below is a highly ported head, but you can see the valve guide work quite well.
teardropping is the most aerodynamic shape there is, which is the preferred shape porters use on the valve guide area, blunt end towards oncoming airflow. getting as much material as you can from around the guide, this lessens the restriction and leaves what's left aerodynamic. this little bit may not be noticeable in the seat of the pants, but more air = more fuel = more power. big gains are achieved by increasing the intake port volume, this takes lots of time with a cast iorn head. there are some good books out about head porting, aerodynamics, and other related subjects. the best reference is looking at professionally ported heads and asking questions, not everyone is willing to give up this information, but it will save lots of time. good luck
