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All these '68-'69 383-4v RR's and SBees with a/c (stick or auto) came with a slightly detuned 383 with a 10% lower compression ratio and a weaker cam). This was a 383 Commando engine even if some or all of them were badged or called Magnum or "road runner" engines. I never saw a factory documented 440-4v stick car with A/C. But saw a couple of them that "claimed" to be legit (ie undocumented).



Somewhat incorrect , the 330HP 383 , which is what the A/C RR and SB had had the same overstated compression ratio as the 335hp engine , 10.0 , but actually 9.2. The camshaft, valve springs and the tune were the difference.