You are probably correct about what was available in all of those years, but what came from the factory on Imperials was 4 bolt through 1962 and 6 bolt after that. I have several cars from each series and that is the case on each and every one. none of my cars have had their cylinder heads replaced. Paul In a message dated 10/23/2003 11:01:29 PM Eastern Daylight Time, 64imper@xxxxxxxxxxxxx writes: > > > Actually Fel Pro as well as Mopar shop manuals list '59 and early ,60 413 > engines with a 4 bolt pattern for valve covers. The rest ar the same as all > the other 60's on big blocks. > Ray > ----- Original Message ----- > From: "mike sutton" <mikanlin62@xxxxxxxxxx> > To: <mailing-list@xxxxxxxxxxxxxxxx> > Sent: Thursday, October 23, 2003 9:00 PM > Subject: Re: IML: valve cover gasket holes > > > > 59-65 Chrysler big block engines ( 361-383-413 ) used the 4 bolt valve > > cover. The catch to this is that the cylinder heads themselves will > > physically interchange from any 361-383-400-413-426W- and 440, so intake > > manifold gasket and port issues not withstanding, any year can have 4 or 6 > > bolt covers. > > > > Mikey > > 62 Crown Coupe > > > > > >