Hi-Performance Dual Port 040 Head, 90.5 & 92 Bore

OVERVIEW

When you''re ready to move beyond the limitations of stock performance and step into the world of reliable, high-output air-cooled power, the EMPI Hi-Performance Dual Port 040 Head is the industry standard for a reason. Specifically engineered for enthusiasts running 90.5mm or 92mm bore configurationscommon in 1776cc, 1835cc, and 1914cc buildsthis head offers a massive jump in durability and thermal efficiency compared to aging factory castings. Every head starts with a premium 040 casting and is subjected to a precision three-angle valve job performed on a state-of-the-art Rottler seat and guide machine. This ensures an airtight seal and optimized airflow right out of the box, giving your Type 1 engine the breathing room it needs to sustain higher RPMs without the dreaded valve float or seat recession common in lesser builds.

What sets this EMPI 98-1374-B cylinder head apart is the inclusion of race-ready internal components that would normally require expensive machine shop upgrades. We''ve equipped these heads with high-grade stainless steel 35.5mm intake and 32mm exhaust valves, designed to withstand the extreme temperatures of a performance air-cooled engine. Complementing the valves are single hi-rev valve springs and heavy-duty chromoly retainers, providing the necessary tension and strength for spirited driving and high-lift camshaft profiles. Whether you''re building a weekend cruiser, a rugged off-road rail, or a daily driver that needs a bit more "oomph," these heads deliver the perfect balance of "bolt-on" convenience and professional-grade engineering that Appletree Automotive customers have come to expect.

FITMENT

This cylinder head is designed for Volkswagen Type 1 based engines utilizing a 90.5mm or 92mm piston and cylinder kit. It is a direct fit for the following models when equipped with a dual-port upright engine:

• Volkswagen Beetle (Standard & Super Bug): 1966-1977 (Typically used for 1776cc - 1914cc conversions)
• Volkswagen Karmann Ghia: 1966-1974
• Volkswagen Bus / Transporter: 1966-1971 (Bay Window models with Type 1 engines)
• Volkswagen Thing (Type 181): 1973-1974
• Volkswagen Squareback, Fastback, Notchback (Type 3): 1966-1973 (Requires cooling tin modifications for dual port)
• Custom Applications: Sand Rails, Dune Buggies, Trikes, and Baja Bugs utilizing VW air-cooled magnesium or aluminum crankcases.

SPECS

• Casting Type: EMPI Hi-Performance 040 Dual Port
• Bore Size: Machine cut for 90.5mm and 92mm Piston/Cylinders
• Intake Valve Size: 35.5mm Stainless Steel
• Exhaust Valve Size: 32mm Stainless Steel
• Valve Springs: Single Hi-Rev Performance Springs
• Retainers: Heavy-Duty Chromoly Steel
• Valve Job: Precision 3-Angle Performance Cut
• Spark Plug Thread: 14mm (Uses standard 1/2'''' reach spark plugs)
• Combustion Chamber: Approximately 50cc to 52cc (Always verify before assembly)
• Material: High-density Aluminum Alloy for superior heat dissipation

PRO TIPS

1. Verify Combustion Chamber Volume (CCing)

While these heads are machined to high standards, we always recommend "CCing" your combustion chambers before final installation. Small variances in chamber volume can significantly impact your compression ratio, especially when building 1776cc or 1914cc engines where tolerances are tighter. Use a plexiglass plate and a burette to measure the volume. If you find a slight discrepancy between the two heads, you can use a small amount of deck height shim or light fly-cutting to equalize the compression across all four cylinders, ensuring a smoother idle and more consistent power delivery across the RPM range.

2. Check Rocker Arm Geometry and Clearance

Because these heads feature hi-rev springs and chromoly retainers, they are often paired with high-lift performance camshafts. It is critical to check your rocker arm geometry during the mock-up phase. Ensure that the rocker arm is centered on the valve stem at half-lift and that the retainer does not contact the rocker arm or the valve stem seal/guide at full lift. If you are using high-ratio rockers (1.25 or 1.4), you may need to use bolt-on rocker shafts and lash caps to protect the stainless steel valve tips from premature wear. Proper geometry is the secret to a long-lasting valvetrain.

3. Perform a Thorough Pre-Installation Cleaning

Even though these heads arrive "complete," never take a performance part straight from the box to the engine block without a thorough cleaning. During the machining of the 90.5/92mm bore or the 3-angle valve job, tiny aluminum shavings or polishing compound can sometimes hide in the cooling fins or the intake runners. Use a pressurized air line and a mild solvent to blow out all passages and spark plug threads. Additionally, we recommend a "lapping" check with a small amount of fine compound to ensure the valves are seated perfectly after shipping, providing you with the maximum possible compression from the very first turn of the key.