NASCAR issued a technical bulletin to NASCAR Home Track members on Wednesday containing changes to the NASCAR Whelen All-American Series Late Model Stock Car rule book.
The most notable aspect of the bulletin is the approval of the Chevrolet Built Upgrade Kit — widely called the ‘spec engine’ by the Late Model Stock community over the past year and a half. The bulletin also approves the Harrington Enforcer engine.
Additionally, the bulletin effectively discontinues Ford, Chevrolet and Dodge built engines by the start of the 2020 season. The only legal engines at that point will be Chevrolet Built Upgrade, GM 604 type crates, Ford SR347 and the Harrington Enforcer.
Of course, tracks also have final discretion over engine rules. The NASCAR rule book is essentially a standardized suggestion. The complete engine updates can be read in their entirety below:
A. Only engines of a type approved by NASCAR in sub-section 20F-5.4 will be permitted.
• The Ford D347SR crate-type engine will be permitted and must be used as supplied by the
manufacturer and/or per the specifications manual provided by the manufacturer.
• The General Motors #88958604 or # 19318604 crate-type engine will be permitted and must be
used as supplied by the manufacturer and/or per the specifications manual provided by the
• The General Motors “Harrington Enforcer” engine will be permitted and must be used as supplied
by the engine supplier and/or per the specifications manual provided by the engine supplier. The
engine may be purchased as a complete engine assembly or in kit form.
• The General Motors “Upgrade” engine kit will be permitted and must use engine components as
per the specifications manual provided. The Edelbrock part #2701 intake manifold will be the
only intake manifold permitted and must remain as supplied without any modifications. The
maximum rocker arm ratio permitted will be 1.6.
NOTE: The engines listed below will be not be permitted following the completion of 2019 racing
General Motors (Built)
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