David Smith, from Galston, was found guilty of the attacks, which took place over a 16 year-period from 1975 to 1991 in the East Ayrshire town.
He was also convicted of sexually abusing a third girl and physically abusing two girls and a boy.
Smith denied the charges against him and claimed his victims were "scheming" and "liars" but was convicted following a trial at the High Court in Glasgow.
Jailing him, judge Lord Matthews told Smith: "You committed a catalogue of physical and sexual abuse towards children.
"I have seen the victim impact statement which detail in graphic detail your offending. Mere words are inadequate to describe your actions."
Smith was described by one of his rape victims as always being "touchy-feely".
She was first abused by him at seven years old and first raped when she was 10.
The victim told advocate depute Bruce Erroch, prosecuting, that Smith had "stolen her childhood".
He raped her on various occasions between June 1979 and June 1985.
The victim, who is now 45, told the jury that Smith would also beat her with a belt, a poker, a shovel and a wooden spoon.
His other rape victim, now aged 39, told the jury: "I've blocked most of what he did to me out. It was the only way I was able to survive."
First offender Smith was also convicted of sexually abusing a third girl between February 1976 and February 1979.
Smith, who is also known as Darter, engaged in sexual activity with one of his rape victims while she was sleeping in bed with his other rape victim.
A 64-year-old man has been jailed for 10 years for raping two young girls.