I wasn't arguing with you just stating that i've never seen anyone post up about running into federal problems on motor swaps. In cali the 4bt swaps are illegal because they are classified as industrial engines, but there are some loop holes.
My guess is that's just because it is the state agency which refuses registration/title.
The 4bt swap would fall into the "light duty vs heavy duty" section of what I posted. At least, that is what I would assume.
As in this state, when I looked into it, I found the same.
NC statutes that may be applicable...
20‑53.1. Specially constructed vehicle certificate of title and registration.
(a) Specially constructed vehicles shall be titled in the following manner:
(1) Replica vehicles shall be titled as the year, make, and model of the vehicle intended to be replicated. A label of "Replica" shall be applied to the title and registration card. All replica vehicle titles shall be labeled "Specially Constructed Vehicle."
(2) The model year of a street rod vehicle shall continue to be recognized as the manufacturer's assigned model year. The manufacturer's name shall continue to be used as the make with a label of "Street Rod" applied to the title and registration card. All street rod vehicle titles shall be labeled "Specially Constructed Vehicle."
(3) Custom‑built vehicles shall be titled and registered showing the make as "Custom‑built," and the year the vehicle was built shall be the vehicle model year. All custom‑built vehicle titles shall be labeled "Specially Constructed Vehicle."
(b) Inoperable vehicles may be titled, but no registration may be issued until such time as the License and Theft Bureau inspects the vehicle to ensure it is substantially assembled. Once a vehicle has been verified as substantially assembled pursuant to an inspection by the License and Theft Bureau, the Commissioner shall title the vehicle by classifying it in the proper category and collecting all highway use taxes applicable to the value of the car at the time the vehicle is retitled to a proper classification, as described in this section.
(c) Motor vehicle certificates of title and registration cards issued pursuant to this section shall be labeled in accordance with this section. As used in this section, "labeled" means that the title and registration card shall contain a designation that discloses if the vehicle is classified as any of the following:
(1) Specially constructed vehicle.
(2) Inoperable vehicle. (2009‑405, s. 2.)
§ 20‑70. Division to be notified when another engine is installed or body changed.
(a) Whenever a motor vehicle registered hereunder is altered by the installation of another engine in place of an engine, the number of which is shown in the registration records, or the installation of another body in place of a body, the owner of such motor vehicle shall immediately give notice to the Division in writing on a form prepared by it, which shall state the number of the former engine and the number of the newly installed engine, the registration number of the motor vehicle, the name of the owner and any other information which the Division may require. Whenever another engine has been substituted as provided in this section, and the notice given as required hereunder, the Division shall insert the number of the newly installed engine upon the registration card and certificate of title issued for such motor vehicle.
(b) Whenever a new engine or serial number has been assigned to and stamped upon a motor vehicle as provided in G.S. 20‑69, or whenever a new engine has been installed or body changed as provided in this section, the Division shall require the owner to surrender to the Division the registration card and certificate of title previously issued for said vehicle. The Division shall also require the owner to make application for a duplicate registration card and a duplicate certificate of title showing the new motor or serial number thereon or new style of body, and upon receipt of such application and fee, as for any other duplicate title, the Division shall issue to said owner a duplicate registration and a duplicate certificate of title showing thereon the new number in place of the original number or the new style of body.
(c) The notification and registration requirements contained in subsections (a) and (b) of this section regarding an engine change shall be required only if the motor vehicle into which a new engine is installed uses an engine number as the sole means to identify the vehicle. (1937, c. 407, s. 34; 1943, c. 726; 1975, c. 716, s. 5; 2009‑405, s. 3.)
§ 20‑71.3. Salvage and other vehicles – titles and registration cards to be branded.
(a) Motor vehicle certificates of title and registration cards issued pursuant to G.S. 20‑57 shall be branded in accordance with this section.
As used in this section, "branded" means that the title and registration card shall contain a designation that discloses if the vehicle is classified as any of the following:
(1) Salvage Motor Vehicle.
(2) Salvage Rebuilt Vehicle.
(3) Reconstructed Vehicle.
(4) Flood Vehicle.
(5) Non‑U.S.A. Vehicle.
(6) Any other classification authorized by law.
(a1) Any motor vehicle that is declared a total loss by an insurance company licensed and approved to conduct business in North Carolina, in addition to the designations noted in subsection (a) of this section, shall:
(1) Have the title and registration card marked "TOTAL LOSS CLAIM".
(2) Have a tamperproof permanent marker inserted into the doorjamb of that vehicle by the Division, at the time of the final inspection of the reconstructed vehicle, that states "TOTAL LOSS CLAIM VEHICLE". Should that vehicle be later reconstructed, repaired, or rebuilt, a permanent tamperproof marker shall be inserted in the doorjamb of the reconstructed, repaired, or rebuilt vehicle.
(b) Any motor vehicle up to and including six model years old damaged by collision or other occurrence, that is to be retitled in this State, shall be subject to preliminary and final inspections by the Enforcement Section of the Division. For purposes of this section, the term "six model years" shall be calculated by counting the model year of the vehicle's manufacture as the first model year and the current calendar year as the final model year.
These inspections serve as antitheft measures and do not certify the safety or road‑worthiness of a vehicle.
(c) The Division shall not retitle a vehicle described in subsection (b) of this section that has not undergone the preliminary and final inspections required by that subsection.
(d) Any motor vehicle up to and including six model years old that has been inspected pursuant to subsection (b) of this section may be retitled with an unbranded title based upon a title application by the rebuilder with a supporting affidavit disclosing all of the following:
(1) The parts used or replaced.
(2) The major components replaced.
(3) The hours of labor and the hourly labor rate.
(4) The total cost of repair.
(5) The existence, if applicable, of the doorjamb "TOTAL LOSS CLAIM VEHICLE" marker.
The unbranded title shall be issued only if the cost of repairs, including parts and labor, does not exceed seventy‑five percent (75%) of its fair market retail value.
(e) Any motor vehicle more than six model years old damaged by collision or other occurrence that is to be retitled by the State may be retitled, without inspection, with an unbranded title based upon a title application by the rebuilder with a supporting affidavit disclosing all of the following:
(1) The parts used or replaced.
(2) The major components replaced.
(3) The hours of labor and the hourly labor rate.
(4) The total cost of repair.
(5) The existence, if applicable, of the doorjamb "TOTAL LOSS CLAIM VEHICLE" marker.
(6) The cost to replace the air bag restraint system.
The unbranded title shall be issued only if the cost of repairs, including parts and labor and excluding the cost to replace the air bag restraint system, does not exceed seventy‑five percent (75%) of its fair market retail value.
(f) The Division shall maintain the affidavits required by this section and make them available for review and copying by persons researching the salvage and repair history of the vehicle.
(g) Any motor vehicle that has been branded in another state shall be branded with the nearest applicable brand specified in this section, except that no junk vehicle or vehicle that has been branded junk in another state shall be titled or registered.
(h) A branded title for a salvage motor vehicle damaged by collision or other occurrence shall be issued as follows:
(1) For motor vehicles up to and including six model years old, a branded title shall be issued if the cost of repairs, including parts and labor, exceeds seventy‑five percent (75%) of its fair market value at the time of the collision or other occurrence.
(2) For motor vehicles more than six model years old, a branded title shall be issued if the cost of repairs, including parts and labor and excluding the cost to replace the air bag restraint system, exceeds seventy‑five percent (75%) of its fair market value at the time of the collision or other occurrence.
(i) Once the Division has issued a branded title for a motor vehicle all subsequent titles for that motor vehicle shall continue to reflect the branding.
(j) The Division shall prepare necessary forms and doorjamb marker specifications and may adopt rules required to carry out the provisions of this Part. (1987, c. 607, s. 1; 1987 (Reg. Sess., 1988), c. 1105, s. 2; 1989, c. 455, ss. 2, 3; 1989 (Reg. Sess., 1990), c. 916, s. 1; 1997‑443, s. 32.26; 1998‑212, s. 27.8(a); 2003‑258, s. 1.)
§ 20‑128. Exhaust system and emissions control devices.
(a) No person shall drive a motor vehicle on a highway unless such motor vehicle is equipped with a muffler, or other exhaust system of the type installed at the time of manufacture, in good working order and in constant operation to prevent excessive or unusual noise, annoying smoke and smoke screens.
(b) It shall be unlawful to use a "muffler cut‑out" on any motor vehicle upon a highway.
(
c) No motor vehicle registered in this State that was manufactured after model year 1967 shall be operated in this State unless it is equipped with emissions control devices that were installed on the vehicle at the time the vehicle was manufactured and these devices are properly connected.
(d) The requirements of subsection (c) of this section shall not apply if the emissions control devices have been removed for the purpose of converting the motor vehicle to operate on natural or liquefied petroleum gas or other modifications have been made in order to reduce air pollution and these modifications are approved by the Department of Environment and Natural Resources. (1937, c. 407, s. 91; 1971, c. 455, s. 1; 1983, c. 132; 1989, c. 727, s. 9; 1997‑443, s. 11A.119(a); 2000‑134, s. 6.)