NASCAR Clarifies Valve Job Rule on Harrington Enforcer

Along with the clarification of the spindle rule released earlier today, NASCAR also clarified the guidelines of the valve job on the Harrington Enforcer engine.

In the email, they specifically outlined the issue where some engine builders have extended the valve job below the lower edge of the valve seat insert, which they say is not allowed.

The email reads as follows:

“As per the suppliers specification’s manual, the valve job is considered to be anything related to the valves and the valve seat inserts. Anything below the lower edge of the valve seat insert is not part of the valve job. Any work done below the valve seat insert is considered altering the cylinder head as it must remain as manufactured.”

The Harrington Enforcer handbook reads as follows:

The HMS ENFORCER Head must be run as manufactured without modifications other than the following:
1. Head gasket surface may be milled/resurfaced for straightness and to achieve the minimum 61cc combustion chamber volume, however no angle milling of the head will be permitted.
2. Any valve job will be permitted with a valve seat angle of 45° only. The top cut can extend past the edge of the seat into the combustion chamber. Cutting and preparation of the valve job may not extend below the valve seat insert. All seat cuts are concentric to the valve stem centerline. Back cutting of the valves is permitted. No modifications to the cylinder head below the valve seat insert will be allowed. The opening diameter at the bottom of the valve seat insert shall not exceed 1.837 for the intake and 1.382 for the exhaust. (it is not uncommon to have machine marks on the combustion chamber walls caused by performing the valve job)

Vince Midas was disqualified from a Limited Late Model race at Hickory Motor Speedway for this same infraction last season.  Many of the track operators during the NASCAR operators meeting were aware of engine builders manipulating the valve job guidelines in the Harrington Enforcer handbook by citing the NASCAR Whelen All-American Series rulebook guidelines for a valve job according to our source.