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TracTuff RBB/ RBC Filler Neck - V2


Whether you have added a radiator that does not have a fill point or you are just in need of a higher fill point to aid in burping the sometimes troublesome cooling system, the filler neck for the RBB/ RBC/ RSP (K24A, K24A2, K24A4, K24A8, K20Z3, and K20Z4) cylinder head is an entry-level product that gets it done. 

The filler neck starts with a beautifully machined 6061-T6 flange that is designed and machined with a large -16 ORB outlet and a 1/2" NPT heater port. This version has a fabricated exit that points to the driver side fender; an option requested for those chassis that originally came with a PRB/ PRC style (K20A, K20A2, K20A3, K20Z1, and K24A1) cylinder head. The outlet can be configured for standard hose (1.25" OD) or -16 male flare.

NOTE: Made to Order - Contact for ETA - If you are interested in a specific design that varies from this, please email us at The cap bung has a 1/16" NPT port for connection to an overflow and uses early model Honda radiator caps; such as an 88'-91' Civic/ CRX or 90'-93' Integra. If you are using AN lines, I recommend designing the upper radiator hose so that there is droop/ give... so the engines movement and does not push/ pull on the radiator and fatigue any parts.

The hardware includes four M8 stainless steel socket head bolts, a 90° heater hose fitting, a plug in the event you don't plan on connecting a heater hose, and a Genuine Honda gasket. The sensor port selection is optional, if you don't have/ need a sensor, don't select it. I only offer two threads... 1/8" NPT or 1/8" BSPT (Honda Single Prong Sensor).