I've found 413s to be more finicky about octane than 440s. My '63 & '62 were happiest running at their design octane of 97, but I wasn't always able to afford a quarter tank of 110 octane racing gas to make it so. They did pretty well on most pump 'super' unleaded. I've also found that some brands of gas work better than other in some cars - my 413 Imperials used to _love_ Amoco super. -Kle. ----------------- http://www.imperialclub.com ----------------- This message was sent to you by the Imperial Mailing List. Please reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be shared with everyone. Private messages (and attachments) for the Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm