C9974 EST motor only gasket kit. 3-13/16" big bore

With .040" MLS (Multi Layer Steel) head gaskets. This EST (Extreme-Sealing-Technology) gasket sets are complete with all gaskets; seals and o-rings that are used on the specific H-D model that is mentioned; excluding primary gaskets. It''s the easy way to do a complete overhaul and have all gaskets that are necessary in one package to reassemble the engine. This EST gasket set contain MLS (Multi-Layer-Steel) head gaskets which eliminates the use of dowel pin o-rings. Base gaskets are SLS (Single Layer Steel) .020" thick. They have .005" of high temperature Viton rubber on both sides and are the strongest on the market. Rocker cover gaskets are also .020" thick SLS. They will not weep; extrude; tear or become brittle over time. Exhaust gaskets will not hinder exhaust gas flow and will not fray into the exhaust port. Valve seals utilize Viton rubber and outer springs for a perfect seal. - MLS = Multi-Layer-Steel explained: Consists of a top and bottom layer of stainless spring steel which is covered by high temperature rubber on both sides. The inner ring is also stainless steel. These 3 layer gaskets are rivited together; outside the gasket surface; for ease of installation. MLS head gaskets eliminate the use of dowel pin o-rings.