That's just so not necessary. Both the block and intake surfaces are so pourous there's plenty for sealant to adhere to. If that wasn't the case then why is so much time spent scraping sealant off the block and manifold every time the manifold is taken off?

 

I partially disagree. You can make it work alright without the groove, but the groove definitely helps trap the bead. When I take off a stock manifold, usually the bead that's there just peels right off with no scraping of the block or manifold, even if it's stuck at all. Having it really clean before applying the sealant makes a big difference on how well it will stick - I think that's about the most important thing you can do.

 

I'm a firm believer in not having to deface an engine for something this simple. Especially when throwing little metal particles everywhere.
I can't count the times my intake has been off and back on with zero leaks by either taking special care using either Ultra Black or Copper or the best **** on the market, The Right Stuff and making doubly sure all surfaces are clean. As said.. the metal on both surfaces is porous enough for the sealant to adhere to.

 

That's why I ALWAYS dimple the China Walls and the underside of the intake manifold. This is an old racer's trick that I learned many years ago when I was building BB quarte mile racing that absolutely could NOT leak at the starting line.

Then clean those areas extremely well to remove any trace of oil or grease.

Set the intake straight down with no back and forth movement.

Tighten the intake bolts in the sequence shown in the manuals in at LEAST two steps - three or more is better.

Wait an hour or so, the recheck the torque (35 lbs./ft.) and you'll probably find the torque has lessened. Gaskets, many times, take a set and need to be re-torqued, sometimes three or more times before they finally take a set and hold the torque reading.

Hope this helps.

Jake

 

Be sure you are not chasing a leak from the oil pressure sending unit.

I replaced my intake gasket about a year ago, and noticed the small drips came back a few months ago. I felt back there and thought the intake was leaking again. Then I noticed the oil pressure started getting very low. Changed the oil, but it didn;t help. I then checked the pressure sending unit, and it was leaking; so I replaced it. Oil pressure now reads good and the leak is gone.

Just something to consider before taking the intake off again.

Thomas.

 

Just for the record and maybe put your mind at ease, China Wall leaks are common. Not only on LT1 engines, but all previous year SB engines as well; and let's not forget BBs. They leak a lot in exactly the same location.

That's probably how the old saying came into being, that "A Chevy 'ain't' running if it ain't leaking".

The China Walls are one of the BIG FOUR: China Walls, Timing Chain Cover/Oil Pan, Rear Main Seal, and Valve covers.

Jake

 

Nope, no metal particles flying around. Only indentations/dimples.

Here's how it looks when it's done. Check the rear China Wall.



But, as I posted before, you can do what you want. Dimple it or don't; it's up to you. I ALWAYS do it.

Jake

 

yepp, permatex ultra copper is the BEST and the only silicone i will use, it is great for anything....