| Author | Message | ||
     Rodrob |
With my motor apart, I have an opportunity to polish the heads. It's been decades since I've done this. Any advice, do's and don'ts, gotchas? | ||
| D_adams |
Only do mild cleanup work, I wouldn't get really radical on them. Knife edges for smooth flow, satin finish in the intake, polished on the exhaust. Other than that, just use caution as you proceed, move slowly and take very little bites of it as you go along. Access to a flow bench would be best, but it's not a cheap option. Also, turning and polishing the valve faces and stems won't hurt either. Maybe check with Erik Buell Racing about some lightweight bits to replace the stock stuff with. | ||
| Rodrob |
Thanks D. I also want to get details on your wideband setup if that would be OK. Can we chat? | ||
| 1_mike |
If you want your ports to work well...DO NOT...knife edge the divider, or any other edge. Sharp edges are for velocities well into supersonic speeds. Internal combustion ports do not work well at those speeds. Not car, not motorcycle heads. What's written in the fluid dynamics books was proven long ago, by NASCAR engine builders, by Drag Race engine builders, by road race engine builders...even by Aircraft wing designers. "Rounded" edges work at subsonic speeds....the same speeds you'll find in ANY internal engine....yes, even at redline rpm's..! Why do you think they are designed this way from the factories..? It's just as easy to design and cast a sharp edge as it is to cast a round edge.... Yea...I've got about 30 years porting bike and car cylinder heads. Even lived off of it a few years back when jobs were thin. I've worked with the experts, the flow benches and my own scrapped heads to learn from. Your heads, your decision, your port flow. Do some research in porting before you get started with the grinder, might save a set of heads. Mike | ||
| Boogiman1981 |
smooth is king from what i've done with my sbc worked to take edges out and not create new ones anywhere. all motor over 400hp and it's not even sweating. i'd love to see pics of the progress if you don't mind sharing | ||
| Rodrob |
Sharp edges are for velocities well into supersonic speeds. Internal combustion ports do not work well at those speeds. Not car, not motorcycle heads. Do some research in porting before you get started with the grinder, might save a set of heads. I have the above from other sources as well. I am doing research, ergo this post. | ||
| S21125r |
Even with a flow bench it is trial an error until you have built up enough historical data about what a particular head/port likes. The most you should do as "DIY" is to remove casting marks. Also make sure you don't have any sharp edges where the valve seat meets the port. |
