Four Bolt Main

The 2 bolt main 5 7 vortec s were put in the 1500 and 2500 lt.

Four bolt main. This is a brace that bolts across all 5 main caps thus tying them all together and sort of creating a 10 bolt main engine. Using a bridgeport milling machine. How i installed billet steel 4 bolt main caps on a 2 bolt main 454 bbc rat. As consumers fell in love with the idea engineers understood the concept and gm s car sales improved.

The additional bolts result in increased strength allowing the engine to withstand higher power output or rpm. Below is a close up of the different size oil seal housings. Everyone was happy until the 1980 s rolled around and here s what happened. Close up of rear oil seal housings.

The basic arrangement is for each bearing cap to have two bolts but some engines may have four or six bolts per bearing cap often referred to as four bolt mains or six bolt mains engines. Oh so here is my situation i have 2 400 small blocks. Four bolt mains are considered much stronger for high performance use than. One is a two bolt main and the other is a 4 bolt main.

O w of them is going to be turned into a race engine for my 4 door 55 daily driver and the other one is going into my my two door 55 race car i m building. The 4 bolt main parts are on top the 2 bolt main parts are on the bottom half of the picture. The 4 bolt main 5 7 vortec s were put in the 2500 hd and 3500. 4 bolt main housing is on the left and the 2 bolt main housing is on the right.

A 4 bolt main refers to the number of bolts attaching the main bearing caps to the block of an internal combustion engine.