452 head spark plug help
- Thread starter Phoenix440
- Start date
Vaanth
Well-Known Member
FYI....
Late 1970s 440 heads with casting number 4006452 were machined differently for different spark plugs depending on the application. The following describes the differences, usages, and some part number reference information for the different spark plug styles used for these heads and other big block heads.
Heat ranges varied over the years depending on application, but original Chrysler, Mopar, and Champion spark plug numbers are listed in the following table:
NOTE: Champion, and other companies, have consolidated heat ranges and application coverage. The current, or recent, Champion replacement for these spark plug numbers is RJ-12YC or RJ-12Y. The "C" denotes a copper core electrode.
Some current, or former, alternate brand crossover spark plug numbers (roughly equivalent to RJ-12YC) are included in the following table:
NOTE: Numerous spark plug heat ranges and application variations exist. The heat range treatment and application coverage has also changed over the years. The foregoing listing is not all inclusive. Crossover between brands is also not always an exact match.
1973 440-3 industrial/truck engines with casting number 3751213 heads also used 14mm, 0.460" reach, tapered seat 5/8" hex spark plugs. These heads were used into 1974 and 1975 for the same motor home applications. These heads used the same spark plugs as the 1976 - 1979 440-3 engine.
Original Chrysler, Mopar, and Champion spark plug numbers are listed in the following table:
Champion OBL-9Y is discontinued. Former and current alternate brand crossover spark plug numbers include those listed in the following table:
Excerpted from the document, "Big Block Head Spark Plug Size and Shape Differences", Gary Lewallen, aka Vaanth.
Late 1970s 440 heads with casting number 4006452 were machined differently for different spark plugs depending on the application. The following describes the differences, usages, and some part number reference information for the different spark plug styles used for these heads and other big block heads.
Heads With Gasketed 13/16" Hex Spark Plugs
Regular production passenger car and light truck big block wedge engines (350, 361, 383, 400, 413, 426 wedge, and 440) used 14mm, 3/8" reach, retracted (gasketed), 13/16" hex spark plugs. The spark plug openings have a machined area with a flat surface for the gasketed spark plugs. The 1976 - 1978 400 and 440 engines used head casting number 4006452. The raw 4006452 casting has a small bump in the spark plug hole area which is machined away for the use of the gasketed spark plugs for passenger car and light truck applications.Heat ranges varied over the years depending on application, but original Chrysler, Mopar, and Champion spark plug numbers are listed in the following table:
| Chrysler | Mopar | Champion | Notes |
|---|---|---|---|
| 2642913 | 34P or P-34P | J-11Y | Non resistor |
| 2642989 | 34PR or P-34PR | RJ-11Y | Resistor |
| 2642475 | 35P or P-35P | J-13Y | Non resistor |
| 3438334 | 35PR or P-35PR | RJ-13Y, RJ-13YC | Resistor |
| 2444870 | 66P or P-66P | J-14Y | Non resistor |
| 3755854 | N/A | RJ-87P | Resistor, platinum (1975+) |
NOTE: Champion, and other companies, have consolidated heat ranges and application coverage. The current, or recent, Champion replacement for these spark plug numbers is RJ-12YC or RJ-12Y. The "C" denotes a copper core electrode.
Some current, or former, alternate brand crossover spark plug numbers (roughly equivalent to RJ-12YC) are included in the following table:
| Brand | Number | Notes |
|---|---|---|
| Champion | J-12Y | Non resistor, discontinued |
| Champion | J-12YC | Non resistor |
| Champion | RJ-12YC | Resistor |
| Champion | J-14Y | Non resistor, discontinued |
| Autolite | 85 or 86 | Resistor |
| Autolite | 75 or 76 | Non resistor, discontinued |
| AC | R44S | Resistor |
| AC | 44S or B44S | Non resistor, discontinued |
| Accel | 0437 | |
| Accel | 0437S | Short |
| Bosch | W7FC | |
| Denso | W16PR-U or W16PRU | |
| NGK | BP5S | Non resistor |
| NGK | BPR5S | Resistor |
| Prestolite | 14-32 | Non resistor, J-11Y |
| Prestolite | 14-42 | Non resistor, J-13Y |
| Prestolite | 14R32 | Resistor, RJ-13Y |
| Prestolite | 14R42 | Resistor, RJ-87P |
| Atlas | C59R, C61R or 461R | Resistor, ~J-12Y, use C61R for J-13Y |
| Atlas | 461 | Non resistor, ~J-12Y |
| Atlas | 459R | Resistor, J-11Y |
| Atlas | 459 | Non resistor, J-11Y |
NOTE: Numerous spark plug heat ranges and application variations exist. The heat range treatment and application coverage has also changed over the years. The foregoing listing is not all inclusive. Crossover between brands is also not always an exact match.
Heads With Tapered Seat 5/8" Hex Spark Plugs
1976 - 1979 440-3 industrial/truck engines used 14mm, 0.460" reach, tapered seat 5/8" hex spark plugs. The heads were the same raw 4006452 casting as other 440 and 400 heads, but were machined with a tapered seat for the smaller plugs, leaving a small bump below the opening. This small bump was to prevent accidental installation of the regular gasketed seat spark plugs. The smaller spark plugs allowed for additional cooling from the water jacket in the head. NOTE: The last 4006452 heads were cast in 1978, but production of the 440-3 engine continued into 1979 in the MB series motor home chassis.1973 440-3 industrial/truck engines with casting number 3751213 heads also used 14mm, 0.460" reach, tapered seat 5/8" hex spark plugs. These heads were used into 1974 and 1975 for the same motor home applications. These heads used the same spark plugs as the 1976 - 1979 440-3 engine.
Original Chrysler, Mopar, and Champion spark plug numbers are listed in the following table:
| Chrysler | Mopar | Champion | Notes |
|---|---|---|---|
| 4091938 | 555PX | OBL-9Y |
Champion OBL-9Y is discontinued. Former and current alternate brand crossover spark plug numbers include those listed in the following table:
| Brand | Number | Notes |
|---|---|---|
| Champion | BL-8Y or BL-9Y | Discontinued |
| Champion | RBL-9Y | Resistor, discontinued |
| Champion | RV-9YC | Resistor |
| Champion | RV-12YC | Hotter plug more suitable for use in passenger cars ,equivalent range to RJ-12YC. |
| Chrysler | 3755840 | Hotter plug more suitable for use in passenger cars ,equivalent range to J-12YC or Mopar 557P. |
| Chrysler | 3874312 | Hotter plug more suitable for use in passenger cars ,equivalent range to RJ-12YC or Mopar 556PR. |
| Chrysler | 3874311 | Resistor, RBL-9Y |
| Mopar | 555PR | Resistor, RBL-9Y |
| Atlas | 433R | Resistor, OBL-9Y |
| Atlas | 433R | Resistor, RBL-9Y |
| Autolite | 23 | |
| Autolite | AR23 or AR12 | Racing |
| NGK | 2623 | |
| NGK | 5034 or 4449 | Racing |
Heads With Long Reach Gasketed 13/16" Hex Spark Plugs
Another head was used in 361 and 413 big block heavy duty trucks, industrial, and some marine, applications from the 1960s into 1974. These heads, casting number 2899943, used a 14mm, 3/4" reach, retracted (gasketed), 13/16" hex spark plug without a projected tip. The plugs have a slight angle mount similar to the small block LA engines. These heads have the water inlets on the front for the large high mounted water pump and completely different exhaust ports than conventional big block wedge engines. The original spark plugs for these heads and applications was Champion N6.Excerpted from the document, "Big Block Head Spark Plug Size and Shape Differences", Gary Lewallen, aka Vaanth.
Last edited:
Phoenix440
Well-Known Member
Thanks, some great info there
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