Pictures comparing 2-bolt and 4-bolt Shortblock Parts:

    Updated 12/24/05

    This picture explains why I did the 4-bolt main conversion. When I dropped the main cradle I saw that one
    bearing was gouged. With the bearing this bad I figured the crank was bad too. The pistons had dings on them
    from the valves so the only parts I would use in a rebuild would be the rods. I decided to get a completly
    new shortblock.


    Dynamic Racing provided these pictures comparing a 2-bolt main block to a 4-bolt main block.

    2-bolt Main 4-bolt Main

    Below is a comparison of 2-bolt main parts and 4-bolt main parts.
    The 4-bolt main parts are on top the 2-bolt main parts are on the bottom half of the picture.


    Below is a close up of the different size oil seal housings.
    4-bolt main housing is on the left and the 2-bolt main housing is on the right


    Close up of rear oil seal housings.
    The 4-bolt housing is new and the 2-bolt housing has form-a-gasket on it.

    endseal0152 endseal0142

    Now the Timing Belt Cover
    2-bolt cover on the left, 4-bolt cover on the Right


    The transmission stay:
    The bracket that bolts between the engine and transmission is also different on one side.
    The 4-bolt stay is the new one on top.
    You can see it has just a little extra clearance to clear the slightly bigger 4-bolt oil pan.

    Another picture:


    Return to 4-bolt main swap page