Heres a little info. introduced in 1969 for use on 250&255hp 350's 73.26cc chamber 1.94 int. 1.50 ex. then used on 400's fitted with 1 5/8 ex.also open chamber design good flowing heads.hope this helps some.
[ April 25, 2002: Message edited by: wrenchturner ]</p>
i think they are good for 9.2 to 1 compression with flat tops. and will obviously need stainless steel seats if not equiped. that's an extra $225 at the machine shop. makes those 400/pr vortex heads look mighty good. unless you already have 3 edelbrock intakes for those heads in your garage. sfb ps don't ask me which chevy dealer (its in texas) sells them for that cheap, cause i aint lookin thru all my old hot rods for that article.