Editing Chevrolet big-block engine (section)

===427 (Z11){{Anchor|Z11}}===
A special {{convert|427|CID|L|1|adj=on}} version of the 409 engine was used in the [[Chevrolet Impala#1963|1963 Impala ''Sport Coupé'']], ordered under Chevrolet [[Regular Production Option]] (RPO) Z11.<ref>{{cite web| title=[Chevrolet's] 1963 Z11 427 Impala |url=http://www.348-409.com/z11.html |date=2015 |website=348-409.com |access-date=April 2, 2015}}</ref> This was a special package created for [[Drag racing|drag racers]], as well as [[NASCAR]],<ref>{{cite AV media |last=RK Motors Charlotte |title=132954 / 1963 Chevrolet Impala SS |url=https://www.youtube.com/watch?v=EU-DXTz8ppo |archive-url=https://ghostarchive.org/varchive/youtube/20211222/EU-DXTz8ppo |archive-date=2021-12-22 |url-status=live|date=June 28, 2013 |website=YouTube |access-date=April 7, 2016}}{{cbignore}}</ref> and it consisted of a cowl-induction {{cvt|427|cuin|L|1}} engine and body with selected aluminum stampings. The aluminum body parts were fabricated in [[Flint, Michigan]] at the facility now known as GM Flint Metal Center.<ref>{{cite web |title=GM U.S. Facilities – Flint Metal Center – Plant Summary |url=http://www.gmdynamic.com/company/gmability/environment/plants/facility_db/facility_summary.php?fID=146 |date=2005 |archive-url=https://web.archive.org/web/20061106023649/http://www.gmdynamic.com/company/gmability/environment/plants/facility_db/facility_summary.php?fID=146 |archive-date=November 6, 2006 |url-status=dead |website=GM Global Operations |access-date=April 2, 2015}}</ref> Unlike the later, second-generation 427, it was based on the W-series 409 engine, but with a longer {{cvt|3.65|in|mm|1}} stroke. A high-rise, two-piece aluminum intake manifold and dual Carter AFB carburetors fed a 13.5:1 compression ratio to produce an under-rated SAE gross {{cvt|430|hp|0}} and {{cvt|575|lbft|0}}. Fifty RPO Z11 cars were produced at the [[Flint, Michigan auto industry|Flint GM plant]].

Extant GM Documents show 50 Z11 engines were built at the GM [[Tonawanda Engine]] plant for auto production, and 20 partial engines were made for replacement/over-the-counter use. There is no evidence from GM that shows 57 cars were built.{{clarify|What?|date=October 2014}}{{citation needed|date=October 2014}}