400 sbc rear main seal

i have a 1974 400 sbc and have been given rear main seal by the speed shop they claim that the rear seal is the sams as the seal from a 350, i have redone it 4 times and it still leaks like a sive can anyone conferm for me that the seal is indeed the same the block has not been line honned but i am thinking i will use the line hone thicker seal and see if that will help just worried that the larger seal could interfeer with crank main bering tolerances

i am also confused as to what oil pan needs to be used the oridginal pan is gone and i think i may need a specific pan to be sucsessfull
am i on the right track thank yee all


Register now (free) or login to remove ads

The line honed 400 seal will not cause a problem. Did you put sealer under the rear corners of the main cap when you assembled the engine? Did you stagger the rear seal ends? seal lips toward the front of the engine.

The rear main seal is 400 specific. The 400 cranks are 0.20" larger on the mains. I'd find another shop if I were you.

Larry