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Spark Plugs

Spark plug conversion table

 

Spark Plug List
Application notes provided by Don Roubos

Application New Champion Old Champion   A--C     Auto Lite
4-cyl  C-26(c) C-4 76-S(7/8"Hex)
78-S(1 1/8" Hex) 		 

The heat range is not as important an issue as the fact of about 1/2" of metal reaches below the end of the threads. The DB's combustion chamber is configured such, that the spark plugs are up in a recess, and a 'normal' plug will carbon up after the first tour. A longer plug gets the spark closer to the actual combustion area.
Roger "Dodger" Hartley

7/8" spark plugs cold down to hot 

Application New Champion Old Champion A--C Auto Lite
  W-10 0 Com 73 Com  
  W-14 1 Com 74 Com T-7
6-cyl Victory & Senior thru 1928 W-18 (#518)  2 Com C 77L T-9
  W-20 3 Com or  No 20 78 Com T-11
  W-89D 44 18 3077
  W-85N 901    
  W-95D 45    

The bottom three plugs are special extension models Recommended torque for a cast iron head is 37 lb-ft 35 lb-ft for aluminum 10 mm cold down to hot 

Application New Champion Old Champion A--C Auto Lite
  UY-6 Y-4A 104 P-4
  UY-6 Y-6 106  
  UY-6 Y-8 108 P-6

Recommended torque for cast iron head is 14 lb-ft 12 lb-ft for aluminum 14 mm cold down to hot 

Application New Champion Old Champion A--C Auto Lite
  J-57-R J-2 42 A3
  H-8 H-9 43L A5
1932-1942 Aluminum head  CJ-8 (#841)  J-8 45 A7
  UJ-12 J-12 47 A11

Recommended torque is 30 lb-ft for cast iron heads 28 lb-ft for aluminum 18 mm cold down to hot 

Application New Champion Old Champion A--C Auto Lite
  D-6 4 Com 82S  
  D-9 5 Com 83-S B5
  D-14 6 Com 84 B7
1929 6cyl 1930-31 6 & 8 cyl  D-16 (#516)  7 85-S  
1929 6cyl 1930-31 6 & 8 cyl  D-16 (#516)  8 Com 86 B9
  D-21 C-15 87 B11
  D-23 10 Com 88-L 388
  D-89D 49 18A  

The bottom plug is a special extension model Recommended torque for cast iron is 34 lb-ft 32 lb-ft for aluminum heads For 1/2" pipe plugs recommended torque in cast iron is 35 lb-ft All values are for clean lubricate threads. Over tightening a plug with a .025 gap the gap will increase to .031. Created from a 1947 heat range list and current Champion list.