CMS13-Fits solid block 1275 motors, not cooper S. if your engine starts with 12. Then this is for you.Steel center main strap for large bore engines, comes with longer high tensile bolts. Main top cap needs machining flat, no other modifications required. *On all performance A series engines it is essential to ensure accurate and as near permanent location of the center main bearing of the crankshaft as possible. Flexure allowed here, especially at sustained high RPM levels, can cause spun bearings, crank or main cap breakage with severe or mortal damage to the engine.*
