During one of our never-ending technical discussions, Jim Grubbs at Jim Grubbs Motorsports (JGM) suggested that we take a look at the flow difference between 30- and 45-degree valve seats. While ...

OEM valve jobs are usually one or two-angle valve jobs. This is done to keep costs low, and even if they want more airflow, OEMs will often just switch to a larger valve instead of using multi-angle ...

For a high-performance street car, at a minimum you want a precision, three-angle valve job with relatively wide seats able to stand up to years of hot rodding. Quickie parts-store valve jobs won't ...

1) What is head porting and polishing and how does it work?Porting involves shaping and/or polishing the intake port openings, the inside of the ports, the exhaust ports, the bowl area below the valve ...