Only three times since the introduction of NHRA Pro Stock in 1970, has the factory hot rod division been overhauled. When the class was introduced it was done so based on a similar factoring system as was done in Super Stock, its predecessor. Pounds per cubic inch as well as other factors including wheelbase determined the weight each combination raced with.

With the IHRA's Mountain Motor concept snagging all of the major drag racing headlines for its seven-second exploits, the NHRA decided at the end of 1981 to scrap its antiquated system of factoring and adopt a universal displacement and weight.

Our team at CompetitionPlusTV has compiled a season in review of that 1982 season, which features the likes of Lee Shepherd, Bob Glidden, Frank Iaconio and Warren Johnson. You might even see a few cameo appearances in there as well.

Yesterday, in our visit back to the archives, we told the story of the pounds-per-cubic inch era for NHRA Pro Stock. Today, we delve a bit deeper with a look back at the early days of 500-inch Pro Stock. #ClassicDragRacing #dragracingnews - https://t.co/Y4rOIvObgk pic.twitter.com/Sr4NomfzVe

— Competition Plus (@competitionplus) December 19, 2019

Long before the 500-inch Pro Stock became the norm, the NHRA factored the factory hot rods on a pounds per cubic inch basis. We've gone back into our archives for a 2003 article which tells of those days. #DragRacingNews #ClassicDragRacing - https://t.co/iAde8aNRRs pic.twitter.com/DIjzma0v4Y

— Competition Plus (@competitionplus) December 18, 2019