When did the 426-4v Hemi & 427-4v HiRiser become legal?
 

I know these combos appear in the NHRA guides today:
426-4v Race Hemi Mopar
427-4v HiRiser Ford (1964)

But to my knowledge the combos never existed outside of NASCAR.

Were these combos NHRA legal in the 1964-1971 era, and did anybody run them? If so what were they factored at back then?
(Near as I can figure, the Race Hemi & 427HiRiser-8v were factored at 500hp, except the 427HiRiser-8v was factored down to 450hp for its final legal year of 1969).

Does anybody run the 4v combos today?

Re: When did the 426-4v Hemi & 427-4v HiRiser become legal?
 

Deleted, misread.

Re: When did the 426-4v Hemi & 427-4v HiRiser become legal?
 

Pretty good answer here, thread from 3 years ago.
Looks like maybe 15 years ago the Race Hemi 4v and 427 HiRiser 4v became NHRA legal.

But it appears back circa 1964-1971 it was all 8v.

http://classracer.com/classforum/sho...=38252&page=53