273 heads

[James L Miller]

We got 178 cfm @ 28" (converted from 10" H2O) on one intake port on a 920 head. The stock valves with a back cut flowed pretty good. A Manley BBM 1.81" exhaust valve cut down to 1.785" seemed to be best at several points and averaged from .050" to .420" lift. I was kind of surprised that dinky little port (127cc) flowed that good. We never got around to trying any seat or bowl work. Ran out of time and money for the time being. The LD4B lost some flow as the port in the intake is wider than the head.

I think I might have to buy/build my own flow bench and get the tooling for seat work for my mill so I can spend the summer working heads. That's a time consuming process.

[Coleydog]

Originally Posted by James L Miller

We got 178 cfm @ 28" (converted from 10" H2O) on one intake port on a 920 head. The stock valves with a back cut flowed pretty good. A Manley BBM 1.81" exhaust valve cut down to 1.785" seemed to be best at several points and averaged from .050" to .420" lift. I was kind of surprised that dinky little port (127cc) flowed that good. We never got around to trying any seat or bowl work. Ran out of time and money for the time being. The LD4B lost some flow as the port in the intake is wider than the head.

I think I might have to buy/build my own flow bench and get the tooling for seat work for my mill so I can spend the summer working heads. That's a time consuming process.

Funny just did the same thing for some 383 and 340 heads, Got some good 340 heads so I'll see how they make them work, reverse engineering. At least it will be entertaining. If you get them to work no more kissing butt to the big guys.