Mark, My dad always told me "When all else fails, read the directions". I went through various manuals '67, '71 and '78 which I have in my library, all mention using a sealer on the head gasket. I'm sure others will chime in on this. As far as the heads are concerned, all you need to worry about for todays gas is hardened valves seats. A machine shop can ad in hardened steel so that unleaded gas can be run. Not that big of a deal. Also, if you are interested in originality, and I am NOT trying to force this on anyone, I think the '63 big blocks still used a 4 nut valve cover? The later design went to a 5 nut design. This would be a visible difference. Finally, if the block has ben decked and the heads have been true'd, there is a possibility you could raise the compression ratio noticeably. I was concerned about this on the G motor and therefore opted for composite head gaskets to compensate for the unitended rasie in CR. Just my 2 cents. Have fun. RIchard >>> " Mark Lindahl" <mplindahl@xxxxxxxxxxxxx> 01/28/08 3:01 pm >>> Hi Richard, I didn't think of using gasket sealer for the head gaskets until I read the service manual and that's what it said. http://www.imperialclub.com/Yr/1963/FSM/Group09/Page11.htm I have a set of both steel and one that looks like composite. I just read the note with the composite set and it reads do not use sealer. Maybe this sealer was only used for the older steel gaskets? I am thinking of using the steel gaskets. FYI, I am using the newer style, open- chamber heads that I was told are desirable for the gas these days. The head surface was machined to guarantee flatness. Thanks, Mark ----- Original Message ----- From: "Richard Osborne" <richard@xxxxxxxxxxxx> To: "ark Lindahl" <mplindahl@xxxxxxxxxxxxx>; <chrysler300@xxxxxxxxxxxxxxx> Sent: Monday, January 28, 2008 1:27 PM Subject: Re: [Chrysler300] Replacing Heads & Gasket Sealer Mark, Assuming that you are refering to the head gaskets, I never use any sealer on the head gaskets. This is true whether using steel shim or composite gaskets. I strongly recommend having the heads surfaced to ensure the mating surface to the block is flat. Now, if you are talking about the intake gaskets, I prefer Hi- Tack, available at most auto parts stores. For the exhaust, I just use standard gaskets without sealer (even though from the factory, they did not use gaskets here). Best regards, Richard Osborne >>> " Mark Lindahl" <mplindahl@xxxxxxxxxxxxx> 01/28/08 1:21 pm >>> Hi All, The 1963 service manual indicates that Mopar Number 1122893 gasket sealer should be used when replacing the cylinder heads. What is the best currently available material to use? Thanks, Mark Lindahl '63 300 Conv. [Non- text portions of this message have been removed] 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/