K-Series Coolant Adapter Plate – Enables K20 Intake Manifold Installation on K24 Cylinder Head

Description

K-Series Swap Intake Manifold Coolant Adapter Plate – Install K20 Manifold on K24 Head (USA Made)

Description

This K24 Intake Manifold Coolant Adapter allows you to easily install a K20-style intake manifold on any K24 cylinder head. Since K24 engines have the coolant recirculation fitting built into the intake manifold—and K20 manifolds do not—this adapter restores the proper coolant routing for a clean, reliable swap.

The adapter is designed to work with all K24 heads, including the K24Z-Series (R40). It is also suitable for installing K20 or cut RBC manifolds on 9th Gen Civic Si, where the coolant bypass differs slightly. When using this adapter, no additional intake manifold adapter is required.

For swap applications, the adapter includes a 1/8″ NPT port for an aftermarket coolant temperature sensor.

Mounting Options

The adapter can be installed using either:

• The included spring-loaded tab – provides constant pressure for a leak-free seal
• Tapping the head using the integrated blind-hole location

We recommend installing the adapter using Honda Bond or a similar gasket maker. This ensures a strong, long-lasting seal and prevents leaks even when the adapter is not under pressure.

Required Tools (If Tapping the Head)

• 6.5mm drill bit (to finish the blind hole in the adapter)
• 5mm drill bit (to drill the head)
• M6 × 1.0 tap

Installation Procedure

1. Do not install a gasket between the head and the adapter. The adapter must mount directly to the head.
2. Use a 6.5mm (or 1/4″) drill bit to finish the blind hole in the adapter.
3. Mock up the adapter and intake manifold on the head to align the mounting location.
4. Mark the spot, then remove the manifold and adapter.
5. Tape or plug the coolant and intake ports on the head to prevent debris from entering.
6. Drill the head using a 5mm (or 13/64″) bit to a depth of 11–14mm. Mark the drill bit with tape so you don’t go too deep.
7. Carefully tap the hole using an M6 × 1.0 tap. Use lubrication and proceed slowly.
8. Begin with a standard tap to start the thread, then finish with a bottoming tap so the bolt can use more of the hole.
9. Test fit the adapter frequently — it should fit snugly without over-tapping the hole.

Once installed, the adapter provides a secure, leak-free coolant routing solution for K-Series swap enthusiasts running a K20 intake manifold on a K24 head.

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