The stock valve job can be improved on Vortec heads. Mondello got more cfm at high lift after performing his own 35/45/60-degree valve job and 75-degree throat cut, but this sacrificed some flow at lower lift (compare: Intake tests 1 and 3).The stock valve job can be improved on Vortec heads. Mondello got more cfm at high lift af Mondello scribes lines at the widest section of the ports. Look closely and you'll see the scribe mark on the top of the port (bottom of photo) is much higher. This is where Mondello raises the roof to a Fel-Pro (PN 1206) gasket's dimension.Mondello scribes lines at the widest section of the ports. Look closely and you'll see the The intake valve on the left has a 21-degree back cut to improve airflow at low lift. The exhaust gets a 22-degree back cut.The intake valve on the left has a 21-degree back cut to improve airflow at low lift. The Getting the corner radius correct is one of the hardest parts of porting. Mondello uses a tube with a radius equal to the gasket (most gasket manufacturers can supply this info) to scribe and check the marks.Getting the corner radius correct is one of the hardest parts of porting. Mondello uses a Mondello starts on the sides of the valve guide boss bringing them into the mark he's made using a special tool he developed and sells. Once the sides of the guide are done, Mondello begins to teardrop the guide, in the direction of the port to aid airflow around it.Mondello starts on the sides of the valve guide boss bringing them into the mark he's made Blend all high and low spots in the chambers. Make sure to put some old valves in the pockets at all times when working the chambers, and always scribe the gasket opening onto the cylinder head so you don't go too far.Blend all high and low spots in the chambers. Make sure to put some old valves in the pock You'll need a set of stones to finish your porting and a dressing tool to shape the stones. Mondello shapes a large stone to smooth the big radii in the chamber. This helps maintain the proper combustion chamber shape while still smoothing the casting. All flat surfaces on the chamber get smoothed with a sanding disc. The final polish can be done with a flapper.You'll need a set of stones to finish your porting and a dressing tool to shape the stones 1 | 2 | » | View Full Article Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!
