400 SBC Main Seal Replacement ( use the correct seal)

[@wreckanchor]

My machine shop guy let me know this and actually handed me the correct seal when I picked up my 400 block. That was a huge deal to me.

[@oacumulador]

Great video. Thanks so much

[@hueroski]

Great info. thank you

[@jimfallowfield7028]

Thanks for the tip!

[@donrutter6765]

No crosshatching in the cap, they didnt bore it, and ripped you off.

[@optimusprimer4392]

There's a bearing that goes in there settle down

[@HerculesRockefellerESQ]

Chasing an oil leak from the back of my 406 right now that's making me lose my fuckin mind. Guess the motor is coming back out.

[@sstocker31]

Too bad the engine has to come back out.... I've always been an advocate of putting a small dab of sealant along the block register for the main cap, as well as putting the seal in as GM designed it. I use lacquer thinner to clean the ends of the seal and then a small dab of sealant. I assemble it and the let it sit overnight before moving the crankshaft. Best of luck...

[@HerculesRockefellerESQ]

@sstocker31 I did that, learned it from a super stock guy funny enough lol. It's gotta be the wrong seal I used. The block DOES have studs in the mains, so I should have known better. Odds of it being line honed are likely pretty high.

[@jefffrank8072]

⁠@@HerculesRockefellerESQ I have a Chevy 400 that was bored out to a 406 as well. I am struggling with the rear main always leaking my main caps have ARP studs is that a good sign that it needs the 2909 seal?

[@HerculesRockefellerESQ]

@jefffrank8072 pull the main cap off and remove the bearing shell. Lay a straight edge across the saddle where the bearing rides. Or put it on the bearing saddle surface and slide it towards the register for the seal. If it is level across the bearing surface and the seal register, it needs the special seal. If the seal register is taller than the bearing surface, and it makes the straight edge stop or sit at an uneven angle to the main bearing saddle, it needs a regular SBC crank seal. For the most part, if you've got studs, odds are the block had been line bored. Hope you find your leak dude, oil leaks are annoying and frustrating as hell.

[@HerculesRockefellerESQ]

@jefffrank8072 for what its worth, my engine with studs still takes the regular style seal. After I posted that comment I had the engine out and replaced the pan gasket and seal. I've still got a small leak somewhere, but it made a HUGE improvement now that I've got the correct pan gasket on it as well as the new rear main seal. This engine has a weird timing cover/oil pan setup. Driver side dipstick, but a thin front crank seal. 🤦‍♂️ Also, I've added a PCV valve as well. I got an adjustable 'performance' one that you set up with adjustment screws based on your engine vacuum. It's a pretty slick outfit, truthfully. My engine makes like 6" of idle vacuum so regular off the shelf valves wouldn't cut it. Seems to work well so far, and the engine is sealed up well enough that I can actually pull vacuum on the crankcase if I cover the breather up. Lol.