Trickflow Thermactor Plug, 5/8"-11 Outside Thread, 7/16"-14 Internal Thread, Steel, Natural, Small Block Ford SKU TFS-51400265 $13.08 Quantity discounts available QuantityPrice (0)No Reviews yet Number of Pieces Item Custom Price Quantity -+ Add to Cart Details Trick Flow® small block Ford thermactor inserts are designed to thread into your heads to change the thread size. These inserts thread right into the ... Details Back DetailsTrick Flow® small block Ford thermactor inserts are designed to thread into your heads to change the thread size. These inserts thread right into the existing cylinder head ports to allow use of the factory accessory drive bolts. Ratings & ReviewsNo reviews availableBe the first to Write a Review