JE Pistons specifically designed for Nitrous-fed 632 engines using aluminum rods. Valve reliefs fit the following cylinder heads: 12º Raptor, 12º Pro-Filer, Dart Big Chief 14º (program #’s 3815 & 384), Sonny Tru-Pro 14.5º, and Brodix PB1200. Precision CNC machined ring grooves are designed for .043 back-cut top rings, .043 D-wall 2nd rings, and 3/16 oil rings. Compression distance and compression ratio calculated with -.025? deck clearance at listed block height.

Includes:

Pin #990-2930-18-51S (174g)

Double spiro locks (#990-042-CS)

Rail Supports(# 4600-203)

Contact reduction grooves

Double Forced Pin Oilers

Accumulator Grooves

Vertical gas ports for maximum top ring seal

Compression Ratio:

65cc 15.2:1

70cc 14.5:1

77cc 13.6:1