Thanks, Some good info.
I heard the templates were a waste of time:
the Mag article I'm using.
https://www.motortrend.com/how-to/mopp-0507-cylinder-head-porting/Excerpt from Steve:
Critically analyzing our modification plan for the intake port, we started at the bowl area just under the valves, and we could see there were areas where large flow gains could be had. Blending the bowl and opening up the valve job to a spec closer to the full potential of the valve size will usually result in large flow gains. However, gains in these areas on the Magnum heads were modest. While there seemed to be plenty of flow left on the table in these areas, the bowls are proportionately large in comparison to the tight port runners. In contrast, opening up the pushrod constriction unlocked a substantial amount of flow, as did reworking the obstruction at the guide boss. It seems the Magnum's large bowl and small runner work together in kind of a happy harmony, with a balance of flow potential that requires mods at each end of the bowl and runner to significantly impact the overall port flow.
How on earth did you come to the conclusion that home porting the Magnums were a waste of time?
Dulcich says "Even with a basic effort, the exhaust flow improvement was dramatic, gaining a staggering 41percent." He goes on to say "The only question that remains is whether it was worth it. For the level of work involved and the power potential gained, we'd have to answer that with a resounding yes. Thirty-four cfm of intake flow has the potential to add a solid 50-60 hp to a combination built to take advantage of the additional flow, and we'd expect a nice extended power band with the increase in port cross-sectional area and substantial exhaust flow. With gains like that up for grabs, I'd spend a Saturday making cast-iron chips."
Are we reading the same article?
Cast iron heads take a good amount of time to port. I think that the instructions that accompanied the templates said something like 12 hours. And you will taste cast iron for days after that. But my experience mirrors Dulcich's. Definitely worth it!
