Valve Jobs
The motor triangle: durable, power and economy
A good quality valve job is probably the most important aspect when trying to achieve maximum durability, power, and economy. That’s why accurate machine uses the industries best seat and guide equipment, the Sunnen VGS20, Sunnen HS-30 diamond guide hone, and the Sunnen VR6500 valve facer. Every valve job that comes out of accurate machine has at least a 3 angle valve job usually 4 angles, making it better than when it was originally manufactured. Before we start on a valve job the head is first disassembled. The parts are all cleaned and checked for proper tolerances. The head is then vatted, media cleaned and re-vatted. Once the head is cleaned it is also checked for proper tolerances such as guide clearance. Guide clearance is between the valve guide and the valve stem. Excessive clearance will cause oil consumption, power loss, valve damage and seat erosion. If the guide clearance is excessive a new guide must be installed. Once the new guide is installed we diamond hone the guide. Diamond honing allows us to set guide clearance to within 1/20 of one human hair 5 times closer than other machine shops with reamers. Only now can we start on our valve job. With straight properly sized guides, we can get the concentricity to within .001 of an inch, ensuring maximum economy, power, and durability.
Race Valve Jobs
All accurate machines race valve jobs are 5 angles on the intake, and radiused on the exhaust. The valves are also either single or double back cut. Through extensive flow bench work, we have a thorough knowledge of what angles and width’s specific cylinder heads want for maximum airflow. Nothing sets a good port job off like the right valve job. Also when rules restrict porting we can cut the bowls open and set the venturi size without any use of a grinder. When we do a race valve job all the seats are cut to the same depth, so when you check valve to piston in one hole you know that they are all the same. The springs are set for the specific camshaft being used, and the intended application. Before we assemble the heads we install Viton valve stems seals to ensure that they don’t come apart under the most severe racing applications.