Header Flanges, Gaskets

 Finished & Plain Header Flanges, Gaskets.

 
   
 
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CADILLAC - Finished Header Flanges, Plain Header Flanges, Header Flanges with formed Starter Tubes, Header Gaskets


  
There are quite a few Mild Steel header flange designs to pick from on this page.  In fact, so many choices that the selection process might be confusing and may be even disturbing. Don't worry about this.  Once you figure out the basics of what you want to accomplish and are ready to place an order, we'll help you select the best header flange design for your headers.
  
(Stainless Steel header flanges
are not available at this time.)
 
 

365-390-429 Cadillac Finished Header Flanges

1 3/4" OD Finished Header Flanges

1956-67 365-390-429" Cadillac

(Part Number 20202E38.)  Also available with 1 5/8" OD
Starter Tubes and flange thicknesses of 1/4", 5/16", and 3/8".
Starter Tubes are approximately 2" long.
(FYI:  The above Finished Header Flanges were made for a customer in Brisbane, Australia.)

 

Finished Header Flanges

1 3/4" OD Finished Header Flanges

1968-76 368-425-472-500" Cadillac

(Part Number 20210E38.)  Also available with 1 5/8", 1 7/8", and 2" OD
Starter Tubes and flange thicknesses of 1/4", 5/16", and 3/8".
Starter Tubes are approximately 2" long.

  


 

FINISHED Header Flanges (whose part numbers start with 20) are PLAIN Header Flanges (whose part numbers start with 25)
that have 2" long tubes custom formed into the ports in the header flange and then TIG (not MIG) welded.  The header flange is
then ground FLAT to remove any weld beads protruding above the gasket surface plus the ports are internally deburred
to remove any weld beads that may remain inside the port.
  
Where others intentionally leave partially ground weld beads ABOVE the header flanges' gasket sealing area and say that this IMPROVES gasket sealing, we've seen these weld beads end up acting as pivot points that cause the header flange to bend - actually CREATING a gasket sealing problem!  Their way of grinding a flange is much faster as they only grind off the TOPS of the weld beads.  Our way of grinding is MUCH SLOWER (BUT also MUCH BETTER) as we not only remove ALL of the weld bead above the gasket surface, we also grind FLAT the ENTIRE GASKET SURFACE of the header flange to MAXIMIZE the gasket sealing area!

 

NOTE:  Bypass going to the Home page (which is slow to load) by going directly back to the Header Kits page (or any of the other pages/areas listed above).

Header KitsFinished
Header Flanges
Plain
Header Flanges
Header Flanges w/Starter TubesHeader GasketsNotesNote
Explanations.

(Look at the bottom
HEADER FLANGE COMMENTS
area for more
information.)
Engine Description -
Cubic Inch Range
Flange Port Size1, Description
Part
Number
Price2,3Part
Number
Price2Part
Number
Price2,3Part
Number
Price
Photo?Photo?Flange Design Comments
123456789A1234567    123456789A123456789B123456789C1234567123456789A12345678
 49-51 Cadillac
 331"
 1 5/8", Square
20200D$314.50225200D$146.952------------------------ 1Head has one center port for two cylinders.
3/8"-16 bolt threads.
  When ordering, double check you have the correct heads!
 49-51 Cadillac
 331"
 1 3/4", Square
20200E$314.50225200D$146.952------------------------1Head has one center port for two cylinders.
3/8"-16 bolt threads.
  When ordering, double check you have the correct heads!
 52-55 Cadillac
 331"
 1 5/8", Square
20201D$314.50225201D$146.952------------------------ 1Head has one center port for two cylinders.
3/8"-16 bolt threads.
  When ordering, double check you have the correct heads!
 52-55 Cadillac
 331"
 1 3/4", Square
20201E$314.50225201E$146.952------------------------1Head has one center port for two cylinders.
3/8"-16 bolt threads.
  When ordering, double check you have the correct heads!
 56-67 Cadillac
 365-390-429"
 1 5/8", Rectangular
20202D$301.50225202D$146.952------------------------ 1,2Head has one center port for two cylinders.
7/16"-14 bolt threads.
  When ordering, double check you have the correct heads!
 56-67 Cadillac
 365-390-429"
 1 3/4", Rectangular
20202E$301.50225202E$146.95222202E$173.90------------ 1,2Head has one center port for two cylinders.
7/16"-14 bolt threads.
  When ordering, double check you have the correct heads!
 68-81 Cadillac
 368-425-472-500"
 1 5/8", Rectangular
20210D$314.50225210D$146.952------------28210$19.95  
   
 68-81 Cadillac
 368-425-472-500"
 1 3/4", Rectangular
20210E$314.50225210E$146.952------------28210$19.95  
   
 68-81 Cadillac
 368-425-472-500"
 1 7/8", Rectangular
20210E$314.50225210E$146.952------------28210$19.95  
   
 68-81 Cadillac
 368-425-472-500"
 2", Rectangular
20210E$314.50225210E$146.952------------28210$19.95  
   
 "North Star" Cadillac
 Before 2000
 1 1/2", Round
20220C$290.50225220C$146.952------------------------3Uses 8mm header bolts which are very hard to find.  Order extras?
   Narrower design than the 20221 series (more universal).
 "North Star" Cadillac
 Before 2000
 1 5/8", Round
20220D$290.50225220D$146.952------------------------ 3Uses 8mm header bolts which are very hard to find.  Order extras?
   Narrower design than the 20221 series (more universal).
 "North Star" Cadillac
 Before 2000
 1 3/4", Round
20220E$290.50225220E$146.952------------------------ 3Uses 8mm header bolts which are very hard to find.  Order extras?
   Narrower design than the 20221 series (more universal).
 "North Star" Cadillac
 Before 2000
 1 7/8", Round
20220F$290.50225220F$146.952------------------------ 3Uses 8mm header bolts which are very hard to find.  Order extras?
   Narrower design than the 20221 series (more universal).
 "North Star" Cadillac
 2000 & later
 1 1/2", Round
20221C$290.50225221C$146.952------------------------3Uses 8mm header bolts which are very hard to find.  Order extras?
  Taller design that covers slot above exhaust ports.
 "North Star" Cadillac
 2000 & later
 1 5/8", Round
20221D$290.50225221D$146.952------------------------3Uses 8mm header bolts which are very hard to find.  Order extras?
  Taller design that covers slot above exhaust ports.
 "North Star" Cadillac
 2000 & later
 1 3/4", Round
20221E$290.50225221E$146.952------------------------3Uses 8mm header bolts which are very hard to find.  Order extras?
  Taller design that covers slot above exhaust ports.
 "North Star" Cadillac
 2000 & later
 1 7/8", Round
20221F$290.50225221F$146.952------------------------3Uses 8mm header bolts which are very hard to find.  Order extras?
  Taller design that covers slot above exhaust ports.
123456789A12345678Header Flange Design Comments and Explanations.123456789A12345678

 

CUSTOM HEADER FLANGES:  While the above Header Flange Listing is quite comprehensive, because we do so much CUSTOM designing in this area, one must understand that we offer much more.  Based on already existing header flange patterns, over the years we have made header flanges:  (1)  WITHOUT PORTS for customers using the header flanges to seal the exhaust side of the motor or customers machining the exhaust ports in the flanges to match a reshaped/relocated exhaust port;  (2)  WITHOUT BOLT HOLES because the customer wanted to drill the bolt holes themselves so as to locate the ports in the flange relative to the ports in the cylinder head a certain way;  (3)  WITH SMALLER than normal exhaust ports because the flanges were going to be used as SPACERS (between a header and a head) to add clearance to a starter, oil filter, etc.;  (4)  in Finished Header Flanges, WITH PORTS LARGER than normal relative to a tube size so that a smaller tube size header could be built but with a full size exhaust port in the header flange (one that does NOT block exhaust flow out of the head); etc.  In some cases these design revisions are done at no charge but where custom drilling is performed (some movement of the bolt pattern relative to the standard location), there is a $15-25 extra charge for the time involved.  Where only ONE flange is desired out of a set of two, we charge 75% of the pair price due to the setup time involved just to make the first flange.  We do NOT make PURE custom header flanges (i.e. one of a kind designs where only one or two pieces are needed) due to the development time involved.  Header Flanges are made from Mild Steel Plate - NOT available in Stainless Steel.

 


 

1 Port Size:  ROUND PORTS:  This is the Inside Diameter of the ports in the header flange measured in inches.  ON ALL OTHER PORT SHAPES: This is the OD of the header tube measured in inches that, when reshaped, would fit into this port size.  In other words, this dimension does not truly relate to the size of the port  in the header flange but more relates to the tube size specified AFTER being reshaped to approximately match the port in the flange.  Keep in mind that we make many header flanges with several choices of port sizes.  We usually ship the flanges that match the cylinder head port AND the tube size being used as closely as possible.  There are reasons to NOT always ship the best match to the cylinder head port but that is usually due to customer requests or specific needs.  We always ask about this because we see no sense in blocking the exhaust port unless there is a good reason to do so.

To make header building MUCH easier, we supply the header flange with ports (those shaped other than round) sized about 1/16-1/8" oversize from a perfect match so that the tubes do NOT have to be shaped perfectly to be inserted into the port.  Port Shapes:

RD = Round,

OV = Oval,

RE = Rectangular,

SQ = Square,

DD = D-shaped port with flat on bottom in most cases,

SAP = Same Shape(s) As Port(s) in head.

NA = Not Available or Not Applicable

2 Header Flanges are priced as a set which means V8 and V6 sets have two flanges (one for each head). Most other engines have just one flange in a set. There are several exceptions to these rules but, where applicable, they are all noted.  Unless specifically mentioned otherwise, all header flanges are 1/4" thick. If you would like thicker header flanges, add $16.00 for 5/16" or $24.00 for 3/8".  All thicker header flanges are made to order and delay header parts shipments about 3-5 days.  Made to order Header Flanges are NOT returnable.

3 Finished Header Flanges and Header Flanges w/Starter Tubes are shipped with a complete set of header bolts.


NOTE 1:  When ordering these header flanges, be ABSOLUTELY sure you have the heads you think you have.  Every so often somebody buys an engine out of a salvage yard and doesn't realize that, at some earlier date - maybe 20-30 years before, somebody swapped heads.  Since there are three basic exhaust side versions in these early Cadillac engines, the header flanges are not really interchangeable!  If you order the WRONG flanges, you can't send them back when you find out that they don't fit.  Either send us a tracing of the exhaust ports, bolt holes, and exhaust surfaces surrounding the exhaust port so we can check the tracing against our header flanges or buy exhaust gaskets or an engine gasket set for your engine to double check your heads.  (This happens with 1949-1964 Oldsmobile engines too - except that they have FIVE basic exhaust port/bolt pattern configurations!) 

NOTE 2:  These engines used 7/16" bolts for the exhaust manifolds.  We cannot find 7/16" thread header bolts so you will have to either source these yourself or use 7/16" Allen bolts or regular 7/16" hex head bolts.  ANOTHER THING:  Because the bolts on each side of the center port are VERY close to the exhaust tube coming out of the flange, there is minimal room to get a wrench on hex head 7/16" thread bolts (which is why round Allen bolts have some advantage here).  Using Allen Bolts and/or denting the header tube to add more "wrench" room is one way of dealing with this problem.  Another way we've been told is having the heads reworked to accept 3/8" bolts instead of the 7/16" bolts - which then allows the use of standard smaller head header bolts.  If that is done, we can supply these flanges with 1/16" smaller bolt holes to match the smaller 3/8" bolts.  We have lowered the prices of the Finished Header Flanges and the Header Flange Kits due to the deletion of the header bolts.

NOTE 3:  When we designed the "North Star" Cadillac header flanges we decided to offer two different widths (actually flange heights) to deal with the differences seen on the exhaust side of these two cylinder head versions.  The narrower version will fit all of the heads but the taller/wider version (which, by being taller, is also more rigid!) covers an exhaust slot found on the later (2000 and up) heads and, therefore, creates a much more attractive appearance.  Because of machining differences in the two different heads, the wider flange will NOT fit the earlier heads.  (The "wider" version - unavailable elsewhere - is particularly desirable in turbocharged applications due to its greater rigidity.)


HEADER FLANGE DESIGN DISCLAIMER: On ANY header flange made to match ANY performance/racing factory/aftermarket cylinder head, due to the fact that the manufacturer - at any time and without notice, might reshape and/or relocate exhaust ports and/or relocate spark plugs and/or change the angle of the spark plugs - we can NO LONGER guarantee port alignment nor spark plug socket clearance.  If you are using ANY of these "non-production" heads (or have ported heads) and are concerned with possible port misalignment, we will select the best possible header flange to match your exhaust ports IF you send us a tracing of all ports, bolt holes, and surrounding machined edges.  (Note that FAXing is not often accurate enough for our needs.)  There is a $10.00 labor charge (no discount) for comparing tracings to current flange designs.  There is also a custom flange drilling charge of $15.00 when it becomes necessary to relocate the bolt pattern to align ports to the port tracings as accurately as possible - and NOTE that custom drilled header flanges are NOT returnable!  Otherwise, should port misalignments occur, grind flange ports where needed. If spark plug or spark plug socket interference occurs, then modify flange as needed.

 

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