Rear main seal difference

[mherbert]

I would like to know what the difference between the standard sbc 2 piece rear main seal and the line bored 400 rear main seal? What happens if you use a 400 line bored seal on a 350 block? Will it be too tight? or too Loose?

[TBRE]

seals

The line bored seal, part# 2909, is for a 2.841 housing bore (the size the mains are honed to on a 400 main, which is LARGER than the stock 400/350 seal ID). That seal WILL leak in a 350 block, or a 400 block that hasn't been line honed.TB

[parrot69777]

Actually I would think if you put in the over size 400 seal into a regular block....I doubt the crank would turn.