Holden HQ HJ HX HZ WB 396-496 Big Block Chev Pacemaker Headers PH5340

Pacemaker PH5340 headers (extractors) are designed for Holden HQ, HJ, HX, HZ and WB applications converted to a Big Block Chevrolet V8.

Designed for high-capacity Big Block Chev combinations including 396, 402, 409, 427, 454 and 496 cubic-inch engines, PH5340 uses a Tri-Y configuration with substantial 51mm (2") primary pipes, 57mm (2¼") secondary pipes and 76mm (3") outlets.

This combination provides considerably greater exhaust-flow capacity than the Small Block Chev PH5310 and PH5320 headers while providing a purpose-designed header package for a Big Block Chevrolet conversion into the HQ-WB chassis.

IMPORTANT – Correct engine mounting spacers are required. Use the original HQ 350 Chev engine mounting spacers or Pacemaker PEMP350 spacers, fitted RH 1¾" and LH 1¼".

Please check availability and current lead time before ordering.

Key Features

• Tri-Y header design
• Designed for Big Block Chevrolet V8 conversions
• 51mm (2") primary pipes
• 57mm (2¼") secondary pipes
• 76mm (3") outlets
• Suits 396-496 cubic-inch Big Block Chev combinations
• Manual and automatic transmission compatible
• Power steering compatible
• Air conditioning compatible
• Designed for Holden HQ-WB applications

Construction

Pacemaker PH5340 uses a Tri-Y configuration with large 51mm (2") primary pipes feeding into 57mm (2¼") secondary pipes and 76mm (3") outlets.

The large pipe diameters are designed to provide the exhaust-flow capacity required by high-displacement Big Block Chevrolet engines.

Additional Options

Ceramic Coating: PHC10 ceramic coating may be available for improved heat management and corrosion resistance. Please contact Best Mufflers for current availability.

DSF23: Replacement Big Block Chevrolet exhaust manifold/header gaskets are available separately.

PEMP350: Pacemaker engine mounting spacers are available where the correct original HQ 350 Chev spacers are not fitted.

Vehicle Fitment

• Holden HQ: Big Block Chevrolet V8 conversion
• Holden HJ: Big Block Chevrolet V8 conversion
• Holden HX: Big Block Chevrolet V8 conversion
• Holden HZ: Big Block Chevrolet V8 conversion
• Holden WB: Big Block Chevrolet V8 conversion
• Engine Family: Big Block Chevrolet V8
• Common Engine Capacities: 396 / 402 / 409 / 427 / 454 / 496ci
• Transmission: Manual / Automatic
• Drive: Rear-Wheel Drive
• Power Steering: Yes
• Air Conditioning: Yes

PH5340 is an engine-conversion header. The engine capacities listed represent compatible Big Block Chevrolet combinations rather than engines originally fitted by Holden to every HQ-WB model.

Header Specifications

• Part Number: PH5340 L/R
• Brand: Pacemaker
• Design: Tri-Y
• Primary Pipe: 51mm (2")
• Secondary Pipe: 57mm (2¼")
• Outlet: 76mm (3")
• Power Steering: Yes
• Air Conditioning: Yes
• Oxygen Sensor: N/A
• EGR: N/A
• Replacement Gasket: DSF23
• Approximate Fitting Time: 2 hours

Fitment Notes

Engine Conversion: PH5340 is designed for fitting a Big Block Chevrolet V8 into the Holden HQ-WB chassis. Because these are converted vehicles, engine position and associated components must be checked carefully before installation.

Engine Mounting Spacers: PH5340 requires the original HQ 350 Chev engine mounting spacers or Pacemaker PEMP350 spacers. They must be fitted on the correct side:

• RH spacer: 1¾" high
• LH spacer: 1¼" high

Power Steering: PH5340 is listed as power-steering compatible.

Air Conditioning: PH5340 is listed as air-conditioning compatible.

Transmission: PH5340 is listed for manual and automatic applications.

Turbo 350 / Turbo 400 / Powerglide: Your existing application information lists these automatic transmissions as compatible. Current PH5340 application data confirms manual and automatic compatibility, but does not consistently identify every individual automatic transmission, so the exact conversion configuration should be checked before ordering.

Column Automatic: Older application information states that column automatic linkage may require modification. Because conversion layouts vary, linkage and header clearance should be checked during installation.

Protect painted surfaces during trial fitting and check engine mounts, steering, starter motor, transmission, linkages, chassis and exhaust clearance before final tightening.

What's Included

• Pacemaker PH5340 left-side header assembly
• Pacemaker PH5340 right-side header assembly

Header bolts, gaskets and other installation hardware should not be assumed to be included unless specifically confirmed with the current kit before ordering.

Recommended With

• DSF23 Big Block Chev exhaust manifold/header gaskets
• Pacemaker PEMP350 engine mounting spacers where required
• Suitable 3" intermediate pipes, joiners or exhaust adaptors

Why Good Headers & Exhaust Systems Matter

At 4,000 rpm, a 454ci (7.4L) Big Block Chevrolet V8 theoretically draws approximately 14,800 litres of intake air per minute at 100% volumetric efficiency and expels around 44,400 litres of hot exhaust gas per minute at approximately 600°C.

A larger 496ci (8.1L) Big Block Chevrolet V8 theoretically draws approximately 16,200 litres of intake air per minute at the same engine speed and can produce approximately 48,600 litres of hot exhaust gas volume per minute using the same theoretical comparison.

Actual airflow varies with engine capacity, RPM, volumetric efficiency, camshaft, cylinder heads, induction system and engine specification.

A well-designed header and exhaust system helps manage this high gas flow efficiently, reducing restriction and improving exhaust scavenging, torque, throttle response and engine performance.

Installation Tips

PH5340 is a Big Block Chev conversion header, so engine position is particularly important. Confirm the engine mounts and mounting spacers before attempting installation.

Check that the correct 1¾" RH and 1¼" LH engine mounting spacers are fitted.

Check clearance around the steering, starter motor, transmission, column linkage, chassis and floor before final installation.

Because PH5340 uses large 3" outlets, confirm the downstream exhaust configuration before installation.

Professional installation is recommended.

Warranty & Compliance

Pacemaker headers are covered against manufacturing defects subject to Pacemaker's current warranty terms and conditions.

Because PH5340 is intended for an engine conversion, the completed vehicle must comply with applicable Australian state or territory requirements relating to engine conversions, exhaust noise and vehicle modifications.

FAQ

What vehicles do PH5340 headers suit?
PH5340 is designed for Holden HQ, HJ, HX, HZ and WB applications converted to a Big Block Chevrolet V8.

What engines do PH5340 headers suit?
PH5340 is listed for 396-496 cubic-inch Big Block Chevrolet V8 combinations, including commonly used 396, 402, 409, 427, 454 and 496 engines.

Are PH5340 headers Tri-Y?
Yes. PH5340 uses a Tri-Y design.

What size are PH5340 headers?
They use 51mm (2") primary pipes, 57mm (2¼") secondary pipes and 76mm (3") outlets.

Will PH5340 fit a 427 Big Block Chev?
Yes. The 427 Big Block Chevrolet is within the PH5340 application range.

Will PH5340 fit a 454 Big Block Chev?
Yes. The 454 Big Block Chevrolet is one of the principal PH5340 applications.

Will PH5340 fit with power steering?
Yes. PH5340 is listed as power-steering compatible.

Will PH5340 fit with air conditioning?
Yes. PH5340 is listed as air-conditioning compatible.

What engine mounting spacers are required?
PH5340 requires the original HQ 350 Chev engine mounting spacers or Pacemaker PEMP350 spacers, fitted RH 1¾" high and LH 1¼" high.

What gasket suits PH5340?
Current PH5340 application information specifies DSF23.

Can I pick up from the store?
Yes. Pick up is available but must be pre-arranged before collection.

How much is freight?
Freight varies depending on your delivery location and where stock is available. Please contact us for freight charges before ordering. Where possible, we can arrange dispatch from the nearest available product location to help reduce freight costs and delivery times.

Do you ship to the USA?
Yes. Best Mufflers regularly ships exhaust systems and exhaust parts to customers throughout the United States.

Please note that import duties, tariffs, taxes, and customs clearance fees are not included in the product or shipping price. Once your order is processed and the applicable charges are calculated, we will send you a secure payment link to finalise the import duties and tariff charges before dispatch.

Customer Support

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