Header Flanges, Gaskets

  Finished & Plain Header Flanges, Gaskets.

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

Engine Series:

  
 
There are quite a few 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. 
 
 
BB Chev Finished Header Flanges
1 3/4" OD Finished Header Flanges
Big Block Chev Factory Aluminum Heads with raised exhaust port floor
(Part Number 20358E38).  Also available with 1 7/8", 2", and 2 1/8" OD
starter tubes and flange thicknesses of 1/4", 5/16", and 3/8".

Finished Header Flange
    1 5/8" OD Finished Header Flanges
Small Block Chev LS engine series (GEN III) D-port version (round also available)
(Part Number 20328DX38).  Also available with 1 3/4", 1 7/8", and 2" OD
starter tubes and flange thicknesses of 1/4", 5/16", and 3/8".
Flange pictured was ordered with extra metal ("X" in part number) added across the
top to increase its rigidity (see Note 40).  (Standard header flange design
has three cutouts on the top matching the three cutouts on the bottom.)
    

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Header Kits Finished
Header Flanges		 Plain
Header Flanges		 Header Flanges w/Starter Tubes Header Gaskets Notes Note
Explanations.

(Look at the bottom
HEADER FLANGE COMMENTS
area for more
information.)
Engine Description -
Cubic Inch Range
Flange Port Size1, Description 		Part
Number 		Price2,3 Part
Number		 Price2 Part
Number		 Price2,3 Part
Number		 Price
Photo? Photo? Flange Design Comments
 SMALL BLOCK - Factory Heads   123456789A123456789B123456789C1234567 123456789A12345678
 55-up Chev
 262-400"
 1 3/8", Round		 20310B $290.502 25310B $146.952 22310B $186.902 28310 $15.40 14 Finished Flange Port will block port in head.
     
 55-up Chev
 262-400"
 1 1/2", Round		 20310C $290.502 25310C $146.952 22310C $186.902 28310 $15.40 14 Finished Flange Port will block port in head.
     
 55-up Chev
 262-400"
 1 5/8", Round		 20310D $290.502 25310D $146.952 22310D $186.902 28310 $15.40 14  
     
 55-up Chev
 262-400"
 1 3/4", Round		 20310E $302.502 25310E $146.952 22310E $186.902 28310 $15.40 14 Tube in Finished Flange hits header bolts.  Must dent tube to clear.
    Port in flange almost touches bolt holes.
 55-up Chev
 262-400"
 1 3/8", Square		 20311B $314.502 25311B $146.952 ------ ------ 28311 $15.40 14,15,16  
    Port in flange plate measures 1.38" wide x 1.44" tall.
 55-up Chev
 262-400"
 1 1/2", Square		 20311C $314.502 25311C $146.952 ------ ------ 28311 $15.40 14,15,16  
    Port in flange plate measures 1.44" wide x 1.50" tall.
 55-up Chev
 262-400"
 1 5/8", Square		 20311D $314.502 25311D $146.952 ------ ------ 28311 $15.40 14,15,16  
    Port in flange plate measures 1.50" wide x 1.56" tall.
 55-up Chev
 262-400"
 1 3/4", Square		 20311E $314.502 25311E $146.952 22311E $186.902 28311 $15.40 14,15,16  
    Port in flange plate measures 1.56" wide x 1.62" tall.
 55-up Chev
 262-400"
 1 7/8", Square		 20311F $314.502 25311F $146.952 ------ ------ 28311 $15.40 14,15,16 May have to dent tube to provide clearance for header bolts.
    Port in flange plate measures 1.63" wide x 1.68" tall.
 55-up Chev
 262-400"
 1 3/8", Square		 20312B $314.502 25312B $146.952 ------ ------ 28312 $15.40 14,15,16  
    Port in flange plate measures 1.47" square.
 55-up Chev
 262-400"
 1 1/2", Square		 20312C $314.502 25312C $146.952 ------ ------ 28312 $15.40 14,15,16  
    Port in flange plate measures 1.53" square.
 55-up Chev
 262-400"
 1 5/8", Square		 20312D $314.502 25312D $146.952 ------ ------ 28312 $15.40 14,15,16  
    Port in flange plate measures 1.59" square.
 55-up Chev
 262-400"
 1 3/4", Square		 20312E $314.502 25312E $146.952 ------ ------ 28312 $15.40 14,15,16 May have to dent tube to provide clearance for header bolts.
    Port in flange plate measures 1.71" square - almost hits holes.
 55-up Chev
 262-400"
 1 5/8", Rectangular		 20313D $314.502 25313D $146.952 ------ ------ 28313 $15.40 14,15,16 Gives more room to header bolts than 312E series flanges do.
    Port in flange plate measures 1.53" wide x 1.65" tall.
 55-up Chev
 262-400"
 1 3/4", Rectangular		 20314E $314.502 25314E $146.952 ------ ------ 28313 $15.40 14,15,16 Gives more room to header bolts than 312E series flanges do.
    Port in flange plate measures 1.65" wide x 1.77" tall.
 55-up Chev
 262-400"
 1 7/8", Rectangular		 20315F $314.502 25315F $146.952 ------ ------ 28313 $15.40 14,15,16 No metal bar between  center ports. Dent tubes to clear header bolts.
    Port in flange plate measures 1.71" wide x 1.84" tall.
 55-up Chev
 262-400" ZZ4 Alum.
 1 1/2", D port		 20316C $314.502 25316C $146.952 ------ ------ 28311 $15.40 14,15,17 Center of Ports .08"-.1" higher than bolt hole centerline
    Port in flange plate measures 1.53" wide x 1.63" tall.
 55-up Chev
 262-400" ZZ4 Alum.
 1 5/8", D port		 20316D $314.502 25316D $146.952 ------ ------ 28311 $15.40 14,15,17 Center of Ports .08"-.1" higher than bolt hole centerline
    Port in flange plate measures 1.59" wide x 1.69" tall.
 55-up Chev
 262-400" ZZ4 Alum.
 1 3/4", D port		 20316E $314.502 25316E $146.952 ------ ------ 28311 $15.40 14,15,17 Center of Ports .08"-.1" higher.  No center bar between center ports.
    Port in flange plate measures 1.71" wide x 1.81" tall.
 SMALL BLOCK - Off Road Factory, Aftermarket Heads   123456789A123456789B123456789C1234567 123456789A12345678
 55-up Chev 262-400"
 "Fast Burn" Aluminum
 1 5/8", D port		 20317D $314.502 25317D $146.952 ------ ------ ------ ------ 14,15,16 Center of Ports .2" higher than bolt hole centerline
    Port in flange plate measures 1.59" wide x 1.69" tall.
 55-up Chev 262-400"
 "Fast Burn" Aluminum
 1 3/4", D port		 20317E $314.502 25317EF $146.952 ------ ------ ------ ------ 14,15,16 Center of Ports .2" higher.  No center bar between center ports.
    Port in flange plate measures 1.71" wide x 1.81" tall.
 55-up Chev 262-400"
 BOW-TIE 18o Rollover
 1 3/4", Round (Alum.)		 20325E $290.502 25325E $146.952 ------ ------ ------ ------  18 Wider Bolt Pattern than factory 6 bolt heads.  See Note 18 below.
     
 55-up Chev 262-400"
 BOW-TIE 18o Rollover
 1 7/8", Round (Alum.)		 20325F $290.502 25325F $146.952 ------ ------ ------ ------  18 Wider Bolt Pattern than factory 6 bolt heads.  See Note 18 below.
     
 55-up Chev 262-400"
 BOW-TIE 18o Rollover
 2", Round (Aluminum)		 20325G $302.502 25325G $146.952 ------ ------ ------ ------  18 Wider Bolt Pattern than factory 6 bolt heads.  See Note 18 below.
     
 55-up Chev 262-400"
 Dart brand Aluminum
 1 3/4", Rectangular		 20160E $314.502 25160E $146.952 ------ ------ ------ ------   Rectangular ports do NOT overlap machined cylinder head bolt  groove below port as round ports do!  Round port flanges leak on the bottom, ours don't!
    Evenly spaced ports.  Known as "Buick" head when introduced.
 55-up Chev 262-400"
 Dart brand Aluminum
 1 7/8", Rectangular		 20160F $314.502 25160F $146.952 ------ ------ ------ ------  
    Evenly spaced ports.  Known as "Buick" head when introduced.
 55-up Chev 262-400"
 Dart brand Aluminum
 2", Rectangular		 20160G $314.502 25160G $146.952 ------ ------ ------ ------   Rectangular ports do NOT overlap machined cylinder head bolt  groove below port as round ports do!  Round port flanges leak on the bottom, ours don't!
    Evenly spaced ports.  Known as "Buick" head when introduced.
 55-up Chev 262-400"
 Dart brand Aluminum
 2 1/8", Rectangular		 20160H $314.502 25160H $146.952 ------ ------ ------ ------  
    Evenly spaced ports.  Known as "Buick" head when introduced.
 55-up Chev 262-400"
 Dart brand Aluminum
 2 1/4", Rectangular		 20160J $314.502 25160J $146.952 ------ ------ ------ ------   Read notes above.
    Evenly spaced ports.  Known as "Buick" head when introduced.
 55-up Chev 262-400"
 Brodix brand Alum.
 1 3/4", Round		 20330E $290.502 25330E $146.952 ------ ------ 28330 $23.55 20 7 Bolt Pattern.  Center ports are farther apart than factory heads.
    "Spread" center exhaust ports.  All models through -11 heads.
 55-up Chev 262-400"
 Brodix brand Alum.
 1 7/8", Round		 20330F $290.502 25330F $146.952 ------ ------ 28330 $23.55 20 7 Bolt Pattern.  Center ports are farther apart than factory heads.
    "Spread" center exhaust ports.  All models through -11 heads.
 55-up Chev 262-400"
 Brodix brand Alum.
 2", Round		 20330G $290.502 25330G $146.952 ------ ------ 28330 $23.55 20 7 Bolt Pattern.  Center ports are farther apart than factory heads.
    "Spread" center exhaust ports.  All models through -11 heads.
 55-up Chev 262-400"
 Brodix brand Alum.
 2 1/8", Round		 20330H $290.502 25330H $146.952 ------ ------ 28330 $23.55 20 7 Bolt Pattern.  Center ports are farther apart than factory heads.
    "Spread" center exhaust ports.  All models through -11 heads.
 55-up Chev 262-400"
 Brodix brand Alum.
 2 1/4", Round		 20330J $290.502 25330J $146.952 ------ ------ 28330 $23.55 20 7 Bolt Pattern.  Center ports are farther apart than factory heads.
    "Spread" center exhaust ports.  All models through -11 heads.
 55-up Chev 262-400"
 Brodix brand Alum.
 1 7/8", Round		 20331F $290.502 25331F $146.951 ------ ------ 28330 $23.55 20 7 Bolt Pattern.  Center ports are farther apart than factory heads.
    "Spread" center ports.  -12 heads and 18o Rollover heads.
 55-up Chev 262-400"
 Brodix brand Alum.
 2", Round		 20331G $290.502 25331G $146.951 ------ ------ 28330 $23.55 20 7 Bolt Pattern.  Center ports are farther apart than factory heads.
    "Spread" center ports.  -12 heads and 18o Rollover heads.
 55-up Chev 262-400"
 Brodix brand Alum.
 2 1/8", Round		 20331H $290.502 25331H $146.951 ------ ------ 28330 $23.55 20 7 Bolt Pattern.  Center ports are farther apart than factory heads.
    "Spread" center ports.  -12 heads and 18o Rollover heads.
 55-up Chev 262-400"
 Brodix brand Alum.
 1 7/8", Round		 20332F $290.502 25332F $146.952 ------ ------ ------ ------ 20 7 Bolt Pattern.  Factory distance on center  exhaust ports.
    Standard Factory Distance on center exhaust ports.
 55-up Chev 262-400"
 Brodix brand Alum.
 2", Round		 20332G $290.502 25332G $146.952 ------ ------ ------ ------ 20 7 Bolt Pattern.  Factory distance on center  exhaust ports.
    Standard Factory Distance on center exhaust ports.
 55-up Chev 262-400"
 Brodix brand Alum.
 2 1/8", Round		 20332H $290.502 25332H $146.952 ------ ------ ------ ------ 20 7 Bolt Pattern.  Factory distance on center  exhaust ports.
    Standard Factory Distance on center exhaust ports.
 55-up Chev 262-400"
 Brodix brand Alum.
 2 1/4", Round		 20332J $290.502 25332J $146.952 ------ ------ ------ ------ 20 7 Bolt Pattern.  Factory distance on center  exhaust ports.
    Standard Factory Distance on center exhaust ports.
 SMALL BLOCK - Inner/Outer Header Flanges, Header Adapter Flanges 123456789A12345678
 55-up Chev 262-400"
 INNER header flanges
 1 5/8", Square 		------ ------ 25320 $211.55 ------ ------ 28311 $15.40 7,20 Must grind ports to match exhaust ports in head.  Read Note 7!
    5/16" thick. Two bolt patterns - one fits standard 6 bolt head.
 55-up Chev 262-400"
 OUTER header flanges
 1 7/8", Round		 20321F $306.50 25321F $163.75 ------ ------ 28321 $19.95 7,20 Bolts to 25320 & 25322 INNER Header flanges. Read Note 7!
    5/16" thick.  Bolts to 25320 flange above.
 55-up Chev 262-400"
 OUTER header flanges
 2", Round		 20321G $306.50 25321G $163.75 ------ ------ 28321 $19.95 7,20 Bolts to 25320 & 25322 INNER Header flanges. Read Note 7!
    5/16" thick.  Bolts to 25320 flange above.
 55-up Chev 262-400"
 OUTER header flanges
 2 1/8", Round		 20321H $306.50 25321H $163.75 ------ ------ 28321 $19.95 7,20 Bolts to 25320 & 25322 INNER Header flanges. Read Note 7!
    5/16" thick.  Bolts to 25320 flange above.
 55-up Chev 262-400"
 OUTER header flanges
 2 1/4", Round		 20321J $306.50 25321J $163.75 ------ ------ 28321 $19.95 7,20 Bolts to 25320 & 25322 INNER Header flanges. Read Note 7!
    5/16" thick.  Bolts to 25320 flange above.
 55-up Chev 262-400"
 INNER header flanges
 1 5/8", Square 		------ ------ 25322 $211.55 ------ ------ ------ ------ 7,20 Must grind ports to match exhaust ports in head.  Read Note 7!
    5/16" thick. Two bolt patterns.  Matches "Fast Burn" heads.
 55-up Chev 262-400"
 ADAPTER flange
 1 5/8", Square		 ------ ------ 25335 $211.552 ------ ------ 28311 $15.40  7,20 Adapts header w/STAHL 7 bolt pattern to standard 6 bolt head.
    5/16" thick.  Matches standard center exhaust port spacing.
 SMALL BLOCK - GEN III - LS7/7.0l  -  LS3, L92/6.2l  -  LS2, LQ4, LQ9/6.0l  -  LS6, LS1/5.7  -  LM4/5.3l  -  LR4/4.8l 123456789A12345678
 LS engine series
 LS7
 1 5/8", D-Port		 20327D $314.502 25327D $146.952 ------ ------ 28329 $22.55 23,40,41 May block sides of ports in some heads. Read Notes.
    Port higher in head relative to bolt pattern.
 LS engine series
 LS7
 1 3/4", D-Port		 20327E $314.502 25327E $146.952 ------ ------ 28329 $22.55 23,40,41 May block sides of ports in some heads. Read Notes.
    Port higher in head relative to bolt pattern.
 LS engine series
 LS7
 1 7/8", D-Port		 20327F $314.502 25327F $146.952 ------ ------ 28329 $22.55 23,40,41 May block sides of ports in some heads. Read Notes.
    Port higher in head relative to bolt pattern.
 LS engine series
 LS7
 2", D-Port		 20327G $314.502 25327G $146.952 ------ ------ 28329 $22.55 23,40,41 May block sides of ports in some heads. Read Notes.
    Port higher in head relative to bolt pattern.
 LS engine series
 LS3, others, not LS7
 1 5/8", D port		 20328D $314.502 25328D $146.952 ------ ------ 28329 $22.55 23,40,41 Uses 8mm header bolts which are very hard to find.  Read Notes.
    Better port match to ports with flat floor.
 LS engine series
 LS3, others, not LS7
 1 3/4", D port		 20328E $314.502 25328E $146.952 ------ ------ 28329 $22.55 23,40,41 Uses 8mm header bolts which are very hard to find.  Read Notes.
    Better port match to ports with flat floor.
 LS engine series
 LS3, others, not LS7
 1 7/8", D port		 20328F $314.502 25328F $146.952 ------ ------ 28329 $22.55 23,40,41 Uses 8mm header bolts which are very hard to find.  Read Notes.
    Better port match to ports with flat floor.
 LS engine series
 LS3, others, not LS7
 2, D port		 20328G $314.502 25328G $146.952 ------ ------ 28329 $22.55 23,40,41 Uses 8mm header bolts which are very hard to find.  Read Notes.
    Better port match to ports with flat floor.
 LS engine series
 All versions but LS7
 1 5/8", Round		 20329D $290.502 25329D $146.952 22329D $186.902 28329 $22.55 23,40,41 May block sides of ports in some heads. Read Notes.
    Round port design makes it easier to build headers.
 LS engine series
 All versions but LS7
 1 3/4", Round		 20329E $290.502 25329E $146.952 22329E $186.902 28329 $22.55 23,40,41 Uses 8mm header bolts which are very hard to find.  Read Notes.
    Round port design makes it easier to build headers.
 LS engine series
 All versions but LS7
 1 7/8", Round		 20329F $290.502 25329F $146.952 22329E $186.902 28329 $22.55 23,40,41 Uses 8mm header bolts which are very hard to find.  Read Notes.
    Round port design makes it easier to build headers.
 LS engine series
 All versions but LS7
 2", Round		 20329F $290.502 25329G $146.952 22329E $186.902 28329 $22.55 23,40,41 Uses 8mm header bolts which are very hard to find.  Read Notes.
    Round port design makes it easier to build headers.
 LS engine series
 All versions but LS7
 2 1/8", Round		 20329F $290.502 25329H $146.952 22329E $186.902 28329 $22.55 23,40,41 Uses 8mm header bolts which are very hard to find.  Read Notes.
    Round port design makes it easier to build headers.
 348-409       123456789A123456789B123456789C1234567 123456789A12345678
 58-61 Chev
 348", small port 409"
 1 5/8", Rectangular		 20340D $314.502 25340D $146.952 ------ ------ 28340 $24.35   409s with small port heads were usually found in trucks.
     All four exhaust ports are the same size.
 58-61 Chev
 348", small port 409"
 1 3/4", Rectangular		 20340E $314.502 25340E $146.952 22340E $186.902 28340 $24.35   409s with small port heads were usually found in trucks.
      All four exhaust ports are the same size.
 62-65 Chev
 409"
 1 3/4", Notes to right		 20341E $314.502 25341E $146.952 ------ ------ 28341 $24.35   End ports are rectangular, center ports are almost square.
    End ports are rectangular, center ports are close to square.
 62-65 Chev
 409"
 1 7/8", Notes to right		 20341F $314.502 25341F $146.952 ------ ------ 28341 $24.35   End ports are rectangular, center ports are almost square.
    End ports are rectangular, center ports are close to square.
 62-65 Chev
 409"
 2", Notes to right		 20341G $314.502 25341G $146.952 ------ ------ 28341 $24.35   End ports are rectangular, center ports are almost square.
    End ports are rectangular, center ports are close to square.
 62-65 Chev
 409"
 2 1/8", Notes to right		 20341H $314.502 25341H $146.952 ------ ------ 28341 $24.35   End ports are rectangular, center ports are almost square.
    End ports are rectangular, center ports are close to square.
 BIG BLOCK   123456789A123456789B123456789C1234567 123456789A12345678
 65-up Chev
 396-502"
 1 3/4", Round		 20350E $290.502 25350E $146.952 22350E $186.902 28350 $15.85 21 Finished Flange Port will block port in head.  Read Note 21.
     Has much more metal around port area than others' flanges!
 65-up Chev
 396-502"
 1 7/8", Round		 20350F $290.502 25350F $146.952 22350F $186.902 28350 $15.85 21 Finished Flange Port will block port in head.  Read Note 21.
     Has much more metal around port area than others' flanges!
 65-up Chev
 396-502"
 2", Round		 20350G $290.502 25350G $146.952 22350G $186.902 28350 $15.85 21 Finished Flange Port may block port in head.  Read Note 21.
     Has much more metal around port area than others' flanges!
 65-up Chev
 396-502"
 2 1/8", Round		 20350H $290.502 25350H $146.952 22350H $186.902 28350H $15.85 21 Read Note 21.
     Has much more metal around port area than others' flanges!
 65-up Chev
 396-502"
 2 1/4", Round		 20350J $290.502 25350J $146.952 22350J $186.902 28350H $15.85 21  Read Note 21.
     Has much more metal around port area than others' flanges!
 65-up Chev
 396-502"
 2 3/8", Round		 20350K $290.502 25350K $146.952 22350K $186.902 28350H $15.85 21 Read Note 21.
     Has much more metal around port area than others' flanges!
 65-up Chev
 396-502"
 2 1/2", Round		 20351L $290.502 25351L $146.952 22351L $186.902 28350H $15.85 21 Can hit head bolts on non-raised port heads.  Read Note 21.
     VERY large port.  Overlaps exhaust surface on some heads.
 65-up Chev
 396-502"
 1 5/8", Square		 20352D $314.502 25352D $146.952 ------ ------ 28352F $15.85 21 Finished Flange Port will block port in head but read Note 21!!!
    When ordering Finished Header Flanges, read Note 21!!!
 65-up Chev
 396-502"
 1 3/4", Square		 20352E $314.502 25352E $146.952 ------ ------ 28352F $15.85 21 Finished Flange Port will block port in head but read Note 21!!!
     When ordering Finished Header Flanges, read Note 21!!!
 65-up Chev
 396-502"
 1 7/8", Square		 20352F $314.502 25352F $146.952 ------ ------ 28352F $15.85 21 Finished Flange Port will block port in head but read Note 21!!!
     When ordering Finished Header Flanges, read Note 21!!!
 65-up Chev
 396-502"
 2", Square		 20352G $314.502 25352G $146.952 ------ ------ 28352F $15.85 21 Read Note 21!!!
     
 65-up Chev
 396-502"
 2 1/8", Square		 20352H $314.502 25352H $146.952 ------ ------ 28352H $19.95 21 Read Note 21!!!
     
 65-up Chev
 396-502"
 2 1/4", Square		 20352J $314.502 25352J $146.952 ------ ------ 28352H $19.95 21 Read Note 21!!!
     
 65-up Chev
 396-502" DART brand
 1 3/4", D port		 20353E $314.502 25353E $146.952 ------ ------ ------ ------ 21 Original "Merlin" head. Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 1 7/8", D port		 20353F $314.502 25353F $146.952 ------ ------ ------ ------ 21 Original "Merlin" head. Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 2", D port		 20353G $314.502 25353G $146.952 ------ ------ ------ ------ 21 Original "Merlin" head. Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 2 1/8", D port		 20353H $314.502 25353H $146.952 ------ ------ ------ ------ 21 Original "Merlin" head. Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 2 1/4", D port		 20353J $314.502 25353J $146.952 ------ ------ ------ ------ 21 Original "Merlin" head. Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 2 3/8", D port		 20353K $314.502 25353K $146.952 ------ ------ ------ ------ 21 Original "Merlin" head. Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 1 3/4", Round		 20354E $290.502 25354E $146.952 22354E $186.902 ------ ------ 21 Finished Flange Port will block port in head but read Note 21!!!
     Original "Merlin" head.
 65-up Chev
 396-502" DART brand
 1 7/8", Round		 20354F $290.502 25354F $146.952 22354F $186.902 ------ ------ 21 Finished Flange Port will block port in head but read Note 21!!!
      Original "Merlin" head.
 65-up Chev
 396-502" DART brand
 2", Round		 20354G $290.502 25354G $146.952 22354G $186.902 ------ ------ 21 Finished Flange Port will block port in head but read Note 21!!!
      Original "Merlin" head.
 65-up Chev
 396-502" DART brand
 2 1/8", Round		 20354H $290.502 25354H $146.952 22354H $186.902 ------ ------ 21 Read Note 21!!!
      Original "Merlin" head.
 65-up Chev
 396-502" DART brand
 2 1/4", Round		 20354J $290.502 25354J $146.952 22354J $186.902 ------ ------ 21 Read Note 21!!!
      Original "Merlin" head.
 65-up Chev
 396-502" DART brand
 2 3/8", Round		 20354K $290.502 25354K $146.952 22354K $186.902 ------ ------ 21 Read Note 21!!!
      Original "Merlin" head.
 65-up Chev
 396-502" DART brand
 1 7/8", D port		 20355F $314.502 25355F $146.952 ------ ------ 28352H $19.95 21 "Merlin II" head (revised port location).
Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 2", D port		 20355G $314.502 25355G $146.952 ------ ------ 28352H $19.95 21 "Merlin II" head (revised port location).
Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 2 1/8", D port		 20355H $314.502 25355H $146.952 ------ ------ 28352H $19.95 21 "Merlin II" head (revised port location).
Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 2 1/4", D port		 20355J $314.502 25355J $146.952 ------ ------ 28352H $19.95 21 "Merlin II" head (revised port location).
Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev
 396-502" DART brand
 2 3/8", D port		 20355K $314.502 25355K $146.952 ------ ------ 28352H $19.95 21 "Merlin II" head (revised port location).
Read Note 21!!!
    MORE metal around port, matches ports BETTER than others.
 65-up Chev 454-502"
 'Crate Motors", etc. 
 1 3/4", D port (alum.)		 20358E $314.502 25358E $146.952 ------ ------ 28352H $19.95 21 Standard port location but floor raised 1/4".  Read Note 21!!!
    Factory Aluminum Head.  Port floor raised 1/4".
 65-up Chev 454-502"
 'Crate Motors", etc. 
 1 7/8", D port (alum.)		 20358F $314.502 25358F $146.952 ------ ------ 28352H $19.95 21 Standard port location but floor raised 1/4".  Read Note 21!!!
    Factory Aluminum Head.  Port floor raised 1/4".
 65-up Chev 454-502"
 'Crate Motors", etc. 
 2", D port (alum.)		 20358G $314.502 25358G $146.952 ------ ------ 28352H $19.95 21 Standard port location but floor raised 1/4".  Read Note 21!!!
    Factory Aluminum Head.  Port floor raised 1/4".
 65-up Chev 454-502"
 'Crate Motors", etc. 
 2 1/8", D port (alum.)		 20358H $314.502 25358H $146.952 ------ ------ 28352H $19.95 21 Standard port location but floor raised 1/4".  Read Note 21!!!
    Factory Aluminum Head.  Port floor raised 1/4".
 V6 - 90 degree   123456789A123456789B123456789C1234567 123456789A12345678
 78-up Chev
 200-229-262"
 1 3/8", Round		 20370B $284.002 25370B $143.552 22370B $186.902 28371 $15.40   Finished Flange Port will block port in head.
     
 78-up Chev
 200-229-262"
 1 1/2", Round		 20370C $284.002 25370C $143.552 22370C $186.902 28371 $15.40   Finished Flange Port will block port in head.
     
 78-up Chev
 200-229-262"
 1 5/8", Round		 20370D $284.002 25370D $143.552 22370D $186.902 28371 $15.40    
     
 78-up Chev
 200-229-262"
 1 3/4", Round		 20370E $296.502 25370E $153.552 22370E $186.902 28371 $15.40   Tube in Finished Flange hits header bolts.  Must dent tube to clear.
     
 78-up Chev
 200-229-262
 1 3/8", Square		 20371B $308.002 25371B $143.552 ------ ------ 28371 $15.40 21.5 Flange Port will block port in head.  Read Note 21.5.
    Finished (by us) Header Flanges are made with larger ports.
 78-up Chev
 200-229-262
 1 1/2", Square		 20371C $308.002 25371C $143.552 ------ ------ 28371 $15.40 21.5 Flange Port will block port in head.  Read Note 21.5.
    Finished (by us) Header Flanges are made with larger ports.
 78-up Chev
 200-229-262
 1 5/8", Square		 20371D $308.002 25371D $143.552 ------ ------ 28371 $15.40 21.5 Read Note 21.5.
     
 78-up Chev
 200-229-262
 1 3/4", Square		 20371E $308.002 25371E $143.552 ------ ------ 28371 $15.40 21.5 Read Note 21.5.
     
 V6 - 60 degree   123456789A123456789B123456789C1234567 123456789A12345678
 80-up Chev
 173"/2.8l Cast Iron Hd.
 1 1/4", Round		 20372A $284.002 25372A $143.552 22372A $186.902 28372 $15.40 23,24 Cast Iron Head.  Finished Flange Port will block port in head.
     Finished Header Flanges with larger ports - add $24.00.
 80-up Chev
 173"/2.8l Cast Iron Hd.
 1 3/8", Round		 20372B $284.002 25372B $143.552 22372B $186.902 28372 $15.40 23,24 Cast Iron Head.  Finished Flange Port will block port in head.
      Finished Header Flanges with larger ports - add $24.00.
 80-up Chev
 173"/2.8l Cast Iron Hd.
 1 1/2", Round		 20372C $284.002 25372C $143.552 22372C $186.902 28372 $15.40 23,24 Cast Iron Head.  Uses 8mm header bolts which are very hard to find.
     
 80-up Chev
 173"/2.8l Cast Iron Hd.
 1 5/8", Round		 20372D $284.002 25372D $143.552 22372D $186.902 28372 $15.40 23,24 Cast Iron Head.  Uses 8mm header bolts which are very hard to find.
     
 80-up Chev
 173"/2.8l   Alum. Head
 1 1/4", Round		 20373A $284.002 25373A $143.552 22373A $186.902 28372 $15.40 23,24 Aluminum Head.  Finished Flange Port will block port in head.
      Finished Header Flanges with larger ports - add $24.00.
 80-up Chev
 173"/2.8l   Alum. Head
 1 3/8", Round		 20373B $284.002 25373B $143.552 22373B $186.902 28372 $15.40 23,24 Aluminum Head.  Finished Flange Port will block port in head.
      Finished Header Flanges with larger ports - add $24.00.
 80-up Chev
 173"/2.8l   Alum. Head
 1 1/2", Round		 20373C $284.002 25373C $143.552 22373C $186.902 28372 $15.40 23,24 Aluminum Head.  Uses 8mm header bolts which are very hard to find.
     
 80-up Chev
 173"/2.8l   Alum. Head
 1 5/8", Round		 20373D $284.002 25373D $143.552 22373D $186.902 28372 $15.40 23,24 Aluminum Head.  Uses 8mm header bolts which are very hard to find.
     
 Inline 6 - Early   123456789A123456789B123456789C1234567 123456789A12345678
 37-62 Chev
 216-235-261'
 1 1/2" & 2" Rectangular		 20300CG $223.602 25300CG $122.502 ------ ------ 28300 $16.65 9,11 Use 1 1/2" tubes on end ports, 2" tubes for shared ports.
    One piece flange has BOTH intake and Exhaust ports.
 Inline 6 - Late   123456789A123456789B123456789C1234567 123456789A12345678
 62-75 Chev
 194-230-250-292"
 1 1/2", Rectangular		 20361C $263.302 25361C $126.352 ------ ------ 28361 $15.85 10,11  
     
 62-75 Chev
 194-230-250-292"
 1 5/8", Rectangular		 20361D $263.302 25361D $126.352 ------ ------ 28361 $15.85 10,11  
     
 4 cylinder   123456789A123456789B123456789C1234567 123456789A12345678
 62-69 Chev
 153"
 1 5/8" Rectangular		 20362D $185.752 25362D $99.952 ------ ------ ------ ------   Does NOT fit the "marine" four exhaust port cylinder head.
    Two tubes exit the one center port in the header flange.
 62-69 Chev
 153"
 1 3/4" Rectangular		 20362E $185.752 25362E $99.952 ------ ------ ------ ------   Does NOT fit the "marine" four exhaust port cylinder head.
    Two tubes exit the one center port in the header flange.
 4 cylinder   123456789A123456789B123456789C1234567 123456789A12345678
 71-75 Chev Vega
 140"/2300cc"
 1 3/8", Round		 20363B $177.802 25363B $88.102 ------ ------ 28363 $15.25    
     
 71-75 Chev Vega
 140"/2300cc"
 1 1/2", Round		 20363C $177.802 25363C $88.102 ------ ------ 28363 $15.25    
     
123456789A12345678 Header 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.

 

   

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 and all welded items (Finished Header Flanges, Custom Collectors, parts with Welded Flanges, etc. are NOT returnable.

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

 

 

NOTE 7: On certain engines, the exhaust side bolt holes are so close to the exhaust ports that it is physically impossible to build larger header tubes due to bolt clearance issues. A combination of INNER and OUTER flanges is now used to allow the construction of larger tube headers on these engines.

The INNER flanges have ports that are on the small side and have to be ground to match the cylinder head. The INNER flanges also have two bolt patterns:

(1) The stock bolt pattern that allows the INNER flange to be bolted to the cylinder head. The stock bolt holes are countersunk so that flat head Allen bolts can be used to hold the INNER flange to the head. The depth of the countersinking is such that the top of the flat head Allen bolts are flush with the outside of the header flange.

(2) The second bolt pattern (seven bolts on the Small Block Chev header flanges is threaded to allow the OUTER flange to be bolted to the INNER flange. This second bolt pattern matches that used by HOOKER HEADERS so header gaskets are easy to find.

While not normally included with plain header flanges, we DO include the necessary bolts with either of these INNER or OUTER header flanges.

Header gaskets are used between the INNER header flanges and the cylinder head and between the OUTER header flanges and the INNER header flanges. Gaskets are NOT included with these flanges.

The 25335 Adapter Flange allows the use of headers built with a flange that has the STAHL seven bolt pattern on a Small Block Chev head with the standard production 6 bolt pattern. The adapter plate has its center ports located to match the center exhaust port locations of standard (NOT spread port) cylinder heads. The Adapter Flange has smaller ports that must be ground to match the head. The plate is threaded to match 3/8-16 bolts (standard coarse thread).

 

NOTE 14:  These flanges can be ordered with an added horizontal metal "pad" area to make adding a bracket for mounting the alternator or generator much easier.  Must specify which side of engine alternator or generator will be mounted.  Add $15.00 for the extra setup time.

 

NOTE 15:  Besides the port sizes listed here, we can make finished header flanges with larger ports in the flanges than listed for a particular tube size.  This is important on smaller tube diameters where the listed port size might block the port in the head to some degree.  Add $24.00 when requesting this on round port flanges.

 

NOTE 16:  Series 311 flanges have tighter radius corners than the series 312, 313, 314, and 315 flanges do.  312 series flanges are closest match to factory port shape.

 

NOTE 18:  Series 325 flanges have a WIDER six bolt pattern than that used in Production Small Block Chevrolet heads.  Measured center to center, the end bolt holes are 2.48" apart and the center bolt holes are 4.63" apart.  (The same measurements in production Small Block Chev heads are 2.22" and 3.95" respectively.)

 

NOTE 20:  Some aftermarket cylinder heads for the Small Block Chev engine are offered with a choice of several bolt patterns - the factory six bolt pattern plus two different seven bolt patterns that look almost the same.  Looking at the drawing below:  One pattern matches that used by HOOKER HEADERS where the dimension A = 3 3/16" and B = 2 15/16".  The other seven bolt pattern matches that used by STAHL HEADERS where A = 3 1/4" and B = 3 1/8".  Note that the "B" measurements for the two different patterns differ the most so use those dimensions when double checking bolt patterns on headers or heads when ordering header flanges from us.

    

Bolt Pattern Drawing

  
     NOTE 21:  Some additional discussion is needed about our Big Block Chev Header Flanges:

350 series:  Round port design with more metal around the exhaust port than is normally found elsewhere. Metal in the bottom of the added area under the port is notched to clear the cylinder head bolts.

351 flange:  2 1/2" round port is huge and can actually extend OUT SIDE of the milled surface of a cylinder head. It can also run into the top of the cylinder head bolts on heads that do NOT have raised ports.

352 series:  The square ports in these flanges match quite well to the square ports found in most of the Big Block Chev Cast Iron heads made by Chevrolet over the past 40+ years.

353 series:  These are flanges with "D" shaped ports designed specifically for the original Dart brand "Merlin" cylinder heads. While not mentioned by the manufacturer, the ports in these heads were moved to the left about .080-.100" and the entire port area and bolt pattern were also moved up about .300". Moving everything up .300" meant that the distance to the cylinder head bolts was increased considerably and we took advantage of that by designing a TOTALLY better header flange for these heads by adding much more metal around the port area to further increase the rigidity of the header flange in that area. This new design makes a standard Big Block Chev header flange actually look "wimpy" by comparison.

354 series:  These are 350 series flanges with relocated bolt patterns that makes the ports align better with the different port location in the original "Merlin" head.

355 series:  These are 353 series flanges with relocated bolt patterns that makes the ports align better with the different port location in the newer "Merlin II" head. This flange also works well on other aftermarket cylinder heads with "D" ports that have been raised at least .300".

358 series:   These are flanges based on the 352 series design but have the floor of the port in the flange raised about a 1/4" to match the raised floor in these aluminum heads offered by Chevrolet.  One issue that must be dealt with is that these heads appear to be wider than other heads as there is a milled notch in the cylinder head near the bottom of the exhaust port that is NOT in other heads for the Big Block Chev engine. It also seems that the area where the cylinder head bolt rests is also higher.  Because of these two differences, we have been told by some customers that they had to grind these flanges to get clearance to the cylinder head bolts.  Keep in mind that this might happen but also that it will happen with ANY Big Block Chev header flange that has not been specifically designed to deal with these two issues!!!!!!!!!!!!!!!!!!!


     NOTE 21.5:  On Header Flange series 370 (round port) for the 90 degree V6 engine, the same OD size tube as the port ID size is used.  The two smaller tube sizes will block the exhaust port.  For an extra $24.00 we will taper the smaller tubes up to fit a 1 5/8" ID flange port which will not block the exhaust port. On Header Flange series 371 (square port) for the 90 degree V6 engine, if we ship plain header flanges, unless requested to do otherwise, we ship flanges with ports sized to match the tube diameters listed.  However, if FINISHED Header Flanges 20371X are ordered in either of the two smaller tube sizes (which are listed to block the exhaust port to some degree), we use the 1 5/8" port plate 25371D and taper the smaller tubes up to the larger port so that the port is NOT blocked.

     NOTE 23:  Uses 8-1.25 x 22mm Header Bolts.  Order extras as these are VERY hard to find!
 
     NOTE 24:  Center-to-center exhaust side bolt hole distances on cast iron heads measure about 2.19", aluminum heads measure about 2.50".  Slot 28373 gasket bolt holes to use them on aluminum heads.
  
     NOTE 40:  On the LS series engines' cylinder heads there are three bolt holes directly above the exhaust port/header flange area.  Most customers do NOT use these three bolt holes.   To IMPROVE upon our original design and make a more rigid header flange, we offer all three of the LS series header flange designs (#327, #328 & #329 series) with EXTRA metal all the way across the top of the header flange (which blocks these three holes).  If you would like this BETTER header flange version, please tell us so or note it somewhere on your order!

     NOTE 41:  To explain the three different header flanges for the GEN III LS Series Small Block Chev engine:
          #329 - Round port design.  Port in flange is centered vertically on port in head.  Round port design makes header building much easier!!
          #328 - D port design.  Top of port located same as #329 but bottom of port is raised and flattened to match bottom of head port better.
          #327 - D port design.  Same as #328 except bolt holes in flange are lowered to raise ports to match higher port location in LS7 head.

 

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, 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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