DeTomaso Mailing List: February 98, Message #143
     



From: 	"Ted A. Mitchell" <tmitch@gte.net>

Subject: Re: '71 Pistons

Date: 	Tue, 3 Feb 1998 14:05:57 +0000



The 70 - 71 351C heads, casting no. DOAE-H, -R  were closed combustion

chamber with a volume of 62.8 cc.  I believe these are the ones used on the

1971 Pantera, and were suppose to have a CR of 11.4:1 with flat top pistons

(although some sources state 10.5:1, maybe the reason for some confusion,

see below).  The 71 Boss heads (closed combustion chamber with adjustable

rocker arms and guide plates), D1ZE-B had a volume of 66.1 cc.  The 71 -74

open chamber heads, D1ZE-DA, D1ZE-GA, had 75.4 cc,



You can vary combustion ratio with with deck height, but closed combustion

chamber heads to piston clearance should never be more than .040, or you

might as well be using open chambers.  I recommend 0 deck height with a

compressed gasket of 0.29 approximately - NOT FOR over 7000 rpm.



TRW did (and I think still does) make a pop-up piston which is rated at 12:1

for the closed head.  The part no. is L-2348.  This is similar to the 1971

Ford Boss pop-up which was only rated to 11.1???????????



Ted (Vader) Mitchell

http://home1.gte.net/tmitch/pe.htm

http://home1.gte.net/tmitch/chpie.htm

http://home1.gte.net/tmitch/index.htm

-----Original Message-----

From: MikeLDrew@aol.com <MikeLDrew@aol.com>

To: Multiple recipients of list <detomaso@realbig.com>

Date: Tuesday, February 03, 1998 9:56 AM

Subject: Re: '71 Pistons





>Steve wrote:

>

>>Pop-ups in 71???  I don't believe that Ford ever used anything but

flattops

>with the quench heads.... at least I haven't seen 'em yet! Not much room at

>all for a dome....

>

>>>>True, but everything I've read and heard says the pushbutton cars had

>11.0:1 compression, while later '71's had the compression lowered to closer

>to 10.0:1, using the same heads.  Wouldn't that lead you to suspect that

mild

>pop-ups had been replaced by flat-tops?  How else would you make the extra

>point of compression go away?

>

>Ted?  Jack?  Anyone here ever taken apart a 69-70-early '71 Cleveland?

>

>Mike

>