They offer a clamp on style reader many use. I usually go by O2 readings but I finally welded two bungs (4 and 6) to get my feet wet this year

1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time