1978 L20b front cover

[maredlin1@hotmail.com]

On the back side of the front cover there is an L shaped groove that runs along side and under the water jackets. I don't know why it's there. My question is, does that groove have to stay open, or will it affect anything if it gets filled with gasket maker ? (I throw most of the paper and cork gaskets away) and use Permatex The Right Stuff. Never a leak, drip , seep or blow out.and vehicle ready to drive in 5 minutes

[datzenmike]

Yes keep it clear, here's why....

 

If the gasket around the water supply into the block should fail, the water will run out this channel. rather than into the oil pan and mixing with the oil. These is also a good chance you will see the leak and get it fixed,

 

Do NOT use gasket maker. That shit is for '50s cars. Put your gasket on dry on clean surfaces, just like Nissan did when they built hundreds of thousands of these engines. You don't need it.

[Draker]

I use a light skim coat of rtv and the gasket. Less is more in this application.

 

Probably could leave it out.. but it works.

[shacks510]

Hmmm. Learn something new every day.

[distributorguy]

New engines don't need gasket maker - on freshly machined surfaces.  Old warped engines can use a little to make up for warping.  "Right Stuff" is pretty fantastic.  My understanding is that it was a product engineered for GM to resolve some minor manufacturing tolerance issues, and its very, very effective.  I used a bunch on my Olds, very very little on the 620.  

[Stoffregen Motorsports]

The key element here is cleanliness. If the mating surfaces are clean and straight, then just the gasket is needed. But this is almost never the case on a 40 year old engine, that is, assuming it's been apart before.

 

Use a razor blade to scrape all the bits of original gasket off. Lightly hit the surfaces with a block sander and some 220 grit paper. Never use a Scotch-Brite Roloc disc on a pneumatic grinder to clean these surfaces.

 

Even with clean and straight surfaces, I still use a skim coat of Gasgacinch http://gasgacinch.com/on the surfaces. This helps make sure that the gaskets are held firmly in place during installation and will also fill some tiny voids in the mating surfaces.

 

Right Stuff is great, and I use it a lot, but mostly on oil pans and diff covers (without a gasket) or on engine surfaces that were designed to use no gasket.