| Header Flange Design History, Discussion, and Explanations
Parts of this page are now under construction (being improved from an earlier version).
HEADER FLANGES
QUICK FIND (by auto manufacturer). We offer Header Kits, Finished Header Flanges, plain Header Flanges, Header Flanges w/formed Starter Tubes, and Header Gaskets for over 100 engines and cylinder heads from the following car manufacturers: We also offer the same items to match a number of aftermarket cylinder heads as well.
While the first set of HEADERS BY "ED" was built in 1962 using header parts obtained elsewhere, from then until about 1970 we used (and sold) header flanges made by other companies. By buying from large companies (actually manufacturers) we were able to obtain header parts at fairly reasonable prices due to their volume production methods. However, because of the custom nature of our HEADERS BY "ED" (as well as the fact we were selling header parts to other shops and individuals), at times it was also quite frustrating and time consuming to deal with these very same products. In particular, header flanges were the biggest pains in the ass because there were too many times that what was offered was simply not what we wanted (or needed): Some times we wanted to build a large tube header for a customer but the header flanges we could find didn't have ports large enough for the tube size to be built which meant we had to waste lots of time hand grinding the ports larger; Other times we wanted to build a small tube header for another customer but the header flanges we could find had ports that were too big which created issues of having to expand the tube into the larger than needed ports (which increased the difficulty - time required - of building the header and also meant the gasket sealing area was unnecessarily reduced); Then we would run into situations where the ports in the heads had not only been ported larger but also reshaped and/or relocated (ports ground considerably more on one side than on the other sides) and found that there were NO header flanges that matched these modifications. On top of all of that sometimes we would purchase header flanges and found them to be near useless because their designs made no sense (couldn't get spark plug sockets on spark plugs, for example). Another issue was that In those earlier days you could only buy 1/4" thick flanges and if you wanted thicker flanges - lots of luck! (They weren't available.) Another issue was trying to get better flange designs from some companies that were actually competitors - we didn't want to tell them how to make their headers better (let them figure that out on their own!). In the summer of 1970 we had a number of issues with the header flanges we were buying elsewhere and finally said to hell with this and decided it was time to figure out how to make our own header flanges. (For what it's worth: Three things I can remember from that summer was that (1) we had ordered 40 square port header flanges for the Big Block Chev engine from one company and when checked on a cylinder head the drilled bolt patterns were so erratic in location (+/- 1/16" error in ANY direction) that only 10 out of the 40 flanges could be used as delivered - the other 30 had to have their ports ground on one or two sides so that when the tubes were welded into the ports they wouldn't hang inside the exhaust port!!!!! Neat! Interesting about this problem was when we complained about this "junk" we were sent, we were told about 4 other header companies that were buying these same header flanges and that they never complained about these flanges. Our comment back was that they obviously weren't checking the flanges! (2) We ordered a number of header flanges for Pontiac Ram-Air IV heads and they showed up 6 months after we ordered them! (3) We had just designed our headers for the 290-401 AMC cars (AMX, Javelin, Hornet, etc.). The 1970 and later AMC V8 heads have an unusually shaped exhaust port (one side kicks out on the bottom under a bolt hole). When we tried to find header flanges to fit this head we didn't find ANY that were acceptable. (Besides matching the unusual port shape in the head, AMC header flanges have to miss the rocker arm cover, have to miss the top of the cylinder head bolts, and also have to give adequate room to the spark plugs so that the spark plug socket can be inserted - WITHOUT COCKING IT - squarely over the spark plug. We found NO header flanges that matched these design requirements! To make matters worse some of the flanges appeared to just be copies of other companys' bad designs so we questioned if anybody was even looking at the design issues that particular head presented. When we finished our flange design for that head, it not only had ports that matched the head ports accurately but it also didn't hit the rocker arm cover OR the cylinder head bolts. It also allowed the spark plug socket to be inserted correctly. While it may not seem to be a big deal to others, we've talked to AMC owners with other brands of headers and have listened to them "bitch" about all the spark plugs they break while changing them. When we point out that the reason why this happens is because their header flanges cause the socket to be cocked (inserted at an angle) on the spark plug and when they "smack" their ratchet handle to "break" the spark plug loose in the threads part of that force goes into the porcelain end of the plug and - oh shit! - the spark plug breaks! One design improvement we incorporated in this AMC header flange design was a lot more metal added around the bottom of the exhaust port area with a "notch" to clear the top of cylinder head bolt! This extra metal - over double that found elsewhere - makes our header flange considerable more rigid and, therefore much better at gasket sealing than anybody else's design. 45 + years later, nobody else has yet done this!
NOT yet done - under construction.
Where many talk about the THICKNESS of their header flanges yet try to see how many flanges they can make out of a given size metal plate, we also design our header flanges to have MORE metal around the exhaust port area to further increase flange rigidity. For example: Look at the pictures and discussion below regarding header flanges for the Big Block Chevrolet engine.
Competitor's 2" Round Port Big Block Chev Header Flange (RED) lying on top of 2" Round Port
Looking more closely at the same flanges, note the misalignment of the exhaust ports. Where our
NOT yet done - under construction.
DESIGN and ORDERING EXPLANATIONS.
Because we offer so much header flange design variety, we know that this can be quite confusing. To hopefully make this less confusing, below you will see the column heading area found
NOTE: Bypass going to the Home page (which is slow to load) by going directly back to the href="headerkits.htm">Header Kits page (or any of the other pages/areas listed above).
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: Information particular to this flange design. NOTE 2: Information particular to this flange design. NOTE 3: Information particular to this flange design. 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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Header Flange Design
History and Discussion
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