Chevrolet Big Block 366 396 402 427 454 V8 Header Flange Plates – FP175-57

FP175-57 exhaust header flange plates are designed for compatible early Chevrolet Mark IV Big Block V8 engines, including 366, 396, 402, 427 and 454ci. Manufactured in Australia from 10mm mild steel with 57mm (2¼") exhaust port openings, these plates are supplied as a pair for custom exhaust header fabrication.

Some aftermarket alloy cylinder heads may require port matching. Confirm exhaust port shape, dimensions and bolt-hole alignment before ordering.

Please check availability and current lead time before ordering.

Key Features

• Designed for compatible early Chevrolet Mark IV Big Block V8 engines
• Suits 366, 396, 402, 427 and 454ci applications, subject to cylinder-head compatibility
• 57mm (2¼") exhaust port openings
• 10mm thick mild steel construction
• Supplied as a pair (2 flange plates)
• Australian made

Construction

• Material: Mild steel
• Thickness: 10mm
• Port opening: 57mm (2¼")
• Suitable for welding into custom exhaust header assemblies

Additional Options

• Bulk quantities available – contact us for pricing and availability
• Other exhaust header flange plate sizes available – contact us for details

Vehicle & Engine Fitment

• Manufacturer: Chevrolet / General Motors
• Engine family: Early Mark IV Big Block V8
• Engine sizes: 366, 396, 402, 427 and 454ci
• Application: Custom exhaust header fabrication
• Important: Fitment depends on cylinder-head exhaust port shape and bolt pattern, not engine displacement alone

Specifications

• Part number: FP175-57
• Port opening: 57mm (2¼")
• Material: Mild steel
• Thickness: 10mm
• Quantity: 2 flange plates (1 pair)
• Manufacture: Australian made

Fitment Notes

• Designed for early Chevrolet Mark IV Big Block cylinder-head applications
• Some aftermarket alloy cylinder heads may require port matching
• Check exhaust port dimensions, shape and bolt-hole alignment before fabrication
• Not intended for Chevrolet 348 or 409 W-series engines, which use different exhaust flange patterns
• Later-generation or aftermarket cylinder heads require individual fitment confirmation

What's Included

• 2 × FP175-57 exhaust header flange plates – one pair for both cylinder heads

Recommended With

• Compatible exhaust header tubing and collectors
• Suitable exhaust flange gaskets and mounting hardware for the cylinder-head application

Installation Tips

• Check flange alignment against the cylinder head before welding
• Confirm the port openings match the intended exhaust header tubing
• Use suitable welding procedures to minimise distortion
• Check the flange mating surfaces after fabrication

Warranty & Compliance

• Australian-made exhaust fabrication component
• Warranty applies to the supplied part only, subject to applicable Australian Consumer Law rights
• Completed exhaust systems must comply with applicable vehicle noise and emissions requirements

Frequently Asked Questions

Which Chevrolet Big Block engines do these flange plates suit?
FP175-57 is intended for compatible early Chevrolet Mark IV Big Block V8 engines, including 366, 396, 402, 427 and 454ci. Check cylinder-head port shape and bolt alignment before ordering.

Are these flange plates sold individually or as a pair?
They are supplied as one pair (2 flange plates), suitable for both cylinder heads.

Will they fit aftermarket alloy cylinder heads?
Some aftermarket alloy cylinder heads may require port matching. Confirm the exhaust port shape and dimensions before ordering.

What size are the exhaust port openings?
Each flange plate has 57mm (2¼") port openings.

How thick are the flange plates?
They are manufactured from 10mm mild steel.

Are these Australian made?
Yes. FP175-57 flange plates are manufactured in Australia.

Can I collect my order?
Yes. Pickup must be pre-arranged. Please contact us before ordering to confirm availability and arrange collection.

How much is freight?
Freight varies depending on your delivery location and stock availability. Please contact us for freight charges before ordering.

Do you ship internationally?
Yes. Please contact us for international freight options and pricing. Import duties and taxes may apply in the destination country.

Customer Support

For phone orders, advice, or part enquiries – contact us: