400 smallblock chevrolet

[DERBYFAN]

Got a 400 that i had the block align bored.I installed a felpro 2909 rear main seal and the rear main still has a leak.Anyone have any tricks to stop the rear main from leaking?

[stock car driver]

I use a standard rear main seal on mine with a zip tie behind it... the over size seal fel pro sells leaked.

Silicone behind the seal to help hold the zip tie.

[Dirtrunner35]

2.8406'' to 2.8415'' is yours bigger

[gadirtracer]

Unless it's pouring, a good, correctly installed "Crack Case Evacuation System" will seal the engine up of those pesky "seeping" leaks.
I say "correctly" 'cause, I've seen ALOT of the pipe fittings stuck way too far into the header and/or too far from the merge of the tubes on the collector.

[Egoracing]

I use a standard rear main seal on mine with a zip tie behind it... the over size seal fel pro sells leaked.

Silicone behind the seal to help hold the zip tie.

How do you put the zip tie on? Where does the head of the tie end up??

[raceman17]

I would think that you would cut the end of the zip tie off. You will be using the thickness of the ziptie as a small spacer to force the seal closer to the crank.

[stock car driver]

How do you put the zip tie on? Where does the head of the tie end up??

duh you cut the head off. lol.

fel pro quit making the over sized seal for a few years because they werent working most of the time. the zip tie is what we used then and still do.

[Egoracing]

duh you cut the head off. lol.

fel pro quit making the over sized seal for a few years because they werent working most of the time. the zip tie is what we used then and still do.

The one I was thinking of is the flat style NOT the standard with the large head. I was thinking that you could clearence the seal enough to clear the flat style tie and put some silicone in behind it. Thanks for the info though!

[Racingtech]

I had the same problem. Get a victor reinz seal # jv1603 made for line bored engines. It solved my oil leak in a 406 race engine. Good luck

[oldgold]

how can you tell if the block has been line bored? Is it something you can see or need to measure?

[stock car driver]

measure rear main cap seal surface

[blncfn57]

how can you tell if the block has been line bored? Is it something you can see or need to measure?

if its been line bored the lip the seal fits on in the block and on the cap will be the same diameter as the block/cap where rear main bearing rides. If it's not line bored the lip will be noticeably smaller diameter by sight and by feel than where the bearing rides. I believe this is really only a big issue with the 400's, but I could be wrong.

[jed408]

are you shore it's the seal and not oil leaking between the cap and the block on the sides.GM always has a thin line of anorobick sealer on each side of the cap.