C 460 flow numbers

hi i have a question on flow numbers on C460 heads....
it dropped 3 exhaust valves on one head not really sure why...the valves were titanium and had about 60 passes on them... i have sent them to a engine machine shop to be repaired...
he rang me and said who ever had ported the heads before hand had not done a very good job..he said the short turn on the intake was like a waterfall he flowed them and said they were 420 at 700 lift and 460 at 900 lift (these guys build a lot of top end race engines)...i have had these heads for about 15 years the guy that did them for me in the beginning said they flowed 500....what should a set of heads like these flow? they are on a boosted engine now 572 cubes i use to run them on a 528 with a single carb and always thought it never went as good as it should...

procharger 528 wrote:hi i have a question on flow numbers on C460 heads....
it dropped 3 exhaust valves on one head not really sure why...the valves were titanium and had about 60 passes on them... i have sent them to a engine machine shop to be repaired...
he rang me and said who ever had ported the heads before hand had not done a very good job..he said the short turn on the intake was like a waterfall he flowed them and said they were 420 at 700 lift and 460 at 900 lift (these guys build a lot of top end race engines)...i have had these heads for about 15 years the guy that did them for me in the beginning said they flowed 500....what should a set of heads like these flow? they are on a boosted engine now 572 cubes i use to run them on a 528 with a single carb and always thought it never went as good as it should...

Usually, the more those heads flow above .750" will lessen the air flows between .300" & .600" so, the peak airflow is not all that important, by itself.
The port contour is all important. SOMETIMES, a sharper edge on the short side radius helps FUEL make the turn and although air flow may suffer, horsepower is improved from better atomization.

Not saying this is what your heads are ... just that it is not as abnormal as you may think.

What size valves, what valve job?

2.45 intake and i think 190 exhaust they are a 45 cut on the seat...

The valve job is hurting the peak numbers, typical stuff on those nowdays is a 55