1965 Valiant 200 convertible (minor project)
I don't know that it matters if the motor is cast or forged crank; it's perfectly fine for street use either way. Now, I have near zero experience with late slant sixes, but I've always heard that slant six cast cranks and forged cranks are not interchangeable; the blocks are different. Below is from William Weertman's History of the Slant 6 engine, part 2, Winter 1992 issue of the Slant 6 News. Note the last sentence.
The same article says that the peanut heads began in the 1975 model year. Also that hydraulic cams were introduced for the 1981 model year.
In Part 3 (Spring 1993 Slant 6 News), Weertman discusses the truck slant sixes. According to him, the shot-peened forged crankshafts of the heavy duty truck engines were discontinued "in 1977 when the crank was redesigned and changed from a forged to a cast type."
This does not seem to allow any slant six forged cranks after 1976, in either trucks or cars.
Of course, even the most experienced person - even one who helped design the slant six - can be wrong every now and then.
But if the OP's engine IS a cast crank motor, then (contrary to what I've seen posted elsewhere) the 030 casting number on the block would not mean it's a forged crank motor.
I'm thinking he has a 1980 cast crank, solid lifter motor.
I don't know that it matters if the motor is cast or forged crank; it's perfectly fine for street use either way. Now, I have near zero experience with late slant sixes, but I've always heard that slant six cast cranks and forged cranks are not interchangeable; the blocks are different. Below is from William Weertman's History of the Slant 6 engine, part 2, Winter 1992 issue of the Slant 6 News. Note the last sentence.
The same article says that the peanut heads began in the 1975 model year. Also that hydraulic cams were introduced for the 1981 model year.
In Part 3 (Spring 1993 Slant 6 News), Weertman discusses the truck slant sixes. According to him, the shot-peened forged crankshafts of the heavy duty truck engines were discontinued "in 1977 when the crank was redesigned and changed from a forged to a cast type."
This does not seem to allow any slant six forged cranks after 1976, in either trucks or cars.
Of course, even the most experienced person - even one who helped design the slant six - can be wrong every now and then.
But if the OP's engine IS a cast crank motor, then (contrary to what I've seen posted elsewhere) the 030 casting number on the block would not mean it's a forged crank motor.
I'm thinking he has a 1980 cast crank, solid lifter motor.