I drove my C300 in Southern CA for many miles and many years without choke action and without a heat riser valve. Worked quite well. Car is a real bear where we live now without manifold heat and choke until engine reaches full operating temp. Heat risers push exhaust under carburetors to heat floor of manifold. Otherwise, fuel condenses big time on floor of manifold during initial cold start and even on colder days. I have worked with thermal choke carbs that have had electric heaters retrofitted. Experiences were never good. Electronic controls did work best but electric assists still brought chokes off way too fast. Bogging and backfiring during warm up. Fouling plugs etc. Carbon build up. Warren Anderson Sedona,AZ [Non-text portions of this message have been removed] ------------------------ Yahoo! Groups Sponsor --------------------~--> See what's inside the new Yahoo! Groups email. http://us.click.yahoo.com/0It09A/bOaOAA/yQLSAA/8LmulB/TM --------------------------------------------------------------------~-> To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/ Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Chrysler300/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/Chrysler300/join (Yahoo! ID required) <*> To change settings via email: mailto:Chrysler300-digest@xxxxxxxxxxxxxxx mailto:Chrysler300-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: Chrysler300-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/