As the topic says, should I?

I'm thinking that I should radius them to match up with my headers (1-3/4) to aid in reversion.

What do you guys do?

 

Matching the flange openings is always worth a little bit more flow. Nothing phenomenal, but a little. As long as you have the grinder on that side of the head, make sure you smooth out the short side radii of the exhaust ports just above the valves. That's going to aid flow and reversion waves for scavenging even more.

 

Thank You Sir.

 

If you mean to aid in anti-reversion, then the secret is to keep the exhaust port slightly smaller than the primary opening, preferably on the short side radii.

If you want reversion then making the ports the same size as the primaries is the right way.

 

Yeah, I was wondering that a little bit myself, but he did definitely say "reversion" after all. Hooker used to even have cones in their header flanges to induce wave reflection (reversion) at the head flange instead of the back of the valve, and hopefully adjusted their tube lengths accordingly. All-out setups always seem to calculate the runner volume and length right down to the back of the valve for best scavenging and tube tuning length. Then again, they're usually using megaphones or flared tips. That would be very difficult on a street engine, and probably not worth any more power after the shock waves fight their way through a converter and muffler.

 

I guess I have my terminology messed up, I had thought that reversion aided in scavenging and by radiuing the port to the header flange would assist it.

That's what happens when I try to use big words

 

Don't need to make the ex port opening huge.
It willl just make your headers more likely to leak.
But you can raise the roof of the port a little to good effect.
Working the bowl and guide area will help flow a lot more than the port exit. No need to get carried away.