Autolite
3923
Direct Match
Thread14 mm x 1.25
Spark Gap0.9 mm (0.035 in)
Reach19 mm (0.75 in)
Hex Size16 mm (0.63 in)
Heat RangeCold-Med
Standard Copper Spark Plug5 Direct
NGK
BKR6E
Cross-reference and physical dimensional analysis for OEM/aftermarket reference BKR6E. Check thread size, reach and electrode gap below before fitting a replacement plug.
Equivalent Part Numbers(5 Cross-Matches)
Sorted by direct catalog match, then by 2-hop transitive inference.
NGK
BKR6EIX
Direct Match
Thread14 mm x 1.25
Spark Gap0.8 mm (0.031 in)
Reach19 mm (0.75 in)
Hex Size16 mm (0.63 in)
Heat Range6 (Iridium)
Partial Equivalence Note
Iridium upgrade replacement for extended service life (60,000+ miles).
Bosch
FR7DC+
Direct Match
Thread14 mm x 1.25
Spark Gap0.8 mm (0.031 in)
Reach19 mm (0.75 in)
Hex Size16 mm (0.63 in)
Heat Range7
Denso
K20PR-U
Direct Match
Thread14 mm x 1.25
Spark Gap0.8 mm (0.031 in)
Reach19 mm (0.75 in)
Hex Size16 mm (0.63 in)
Heat Range20
Champion
RC12YC
Direct Match
Thread14 mm x 1.25
Spark Gap0.9 mm (0.035 in)
Reach19 mm (0.75 in)
Hex Size16 mm (0.63 in)
Heat Range12 (Med)
Comparing the numbers
Thread size and reach must match: a plug that reaches too far into the chamber can strike the piston, and one too short leaves the spark shrouded. Electrode gap is usually adjustable, but follow the figure your engine manufacturer specifies rather than the one a plug ships with.