Enginetech R40638-040 Cast .040″ Oversize Piston Ring Set for 1959-1966 Pontiac 6.4L 389ci V8 – Complete Engine Ring Set

Description

Enginetech R40638-040 is a cast .040″ oversize piston ring set for 1959-1966 Pontiac 6.4L 389ci V8 engines, sold as a complete set covering all cylinders.

Important Notes:

• Sized for cylinders bored .040 inch oversize. Verify your finished bore diameter with a precision gauge before ordering – rings sized for the wrong bore will not seal correctly.
• File-fit and gap each ring to the manufacturer’s end-gap specification for your application before installation. Improper end gap causes blow-by or ring-end butting under heat.
• Replace piston rings as a complete set during any rebuild. One set covers all cylinders for the engine.

Sold as a complete piston ring set – one set covers all cylinders and is required per engine.

Fitment:

1959-1966 Pontiac6.4L 389ci V8

Enginetech piston ring sets are manufactured to OEM specifications and offered in both premium and cast grades to match the demands of stock rebuilds and moderate-performance builds. Each set is application-specific, with ring widths and end-gap characteristics matched to the bore and groove geometry of the engine family it serves. Ring sets are sold by bore size – standard for unmachined bores, with oversizes for blocks that have been bored and honed – so verify your finished bore diameter with a precision gauge before ordering, since rings sized for the wrong bore will not seal correctly. Always file-fit and gap each ring to the manufacturer’s specification for your application, and replace rings as a complete set during any rebuild. Enginetech documents every set with the ring stack dimensions, bore size, and cross-references so the correct set reaches the bench the first time.

WARNING: This product can expose you to chemicals including lead and nickel, which are known to the State of California to cause cancer, birth defects, or other reproductive harm.