472 Intake: to seal or not to seal

[Greg C]

I'm installing a 472 intake  should I install the gasket  dry, copper spray or aviation form a gasket.

[Dan LeBlanc]

Black RTV on everything otherwise you're setting yourself up for leaks.

[klinebau]

what does this mean?

Around all the ports on the block?
Around all the ports on the top of the gasket?

The gasket manufacturer instructions usually call for RTV only in the corners if using the rubber china wall seals.  The service manual only says to use adhesive to keep the gasket from moving.

[TJ Hopland]

The metal gasket is embossed around the ports.   I believe the idea is that the embossed part will crush as needed to make the seal.    I have always seen them dry on the metal and rtv on the rubber ends.

["Cadillac Kid" Greg Surfas 15364]

Second what TJ has just said.  I have NEVER had an issue on a stock motor using the tin pan and rubber china rail seals with RTV on the ends.  The pan serves the second and very important purpose of keeping hot oil off the bottom of the hot intake manifold and "cooking".
Greg Surfas

[TJ Hopland]

One sort of unique thing about these engines is there isn't a coolant passage in the intake.   Maybe that is another difference why many other intakes usually need some sort of sealant? 

Another advantage to these engines when it comes to intakes is its rare to have to do any significant machine work to either the block or heads for a stock rebuild.  These were high nickel blocks and heads that historically didn't get used hard so even at this age when you rebuild one you rarely need more than what amounts to a polish to get new sealing surfaces.   Its a different story with your typical Ford or Chev motor that were not as high quality to begin with and often got used hard.  On those they may have been rebuilt several times or had someone trying to get more out of them and removed a lot of material.   Because of the V configuration that starts to change the geometry of how things like the intake fit.  I think those engines is where many of the stories of sealing issues come from.     

[cadillacmike68]

Make sure it is well sealed. You don't want this to happen: 

["Cadillac Kid" Greg Surfas 15364]

Mike,
It looks like the intake was installed without the "tin pan".
Greg Surfas

[cadillacmike68]

Greg,

There's a fist sized hole in the cookie sheet / tin pan. I'll put the whole story up in my May thread later today. That's not oil drops either. It's rust covered with oil.

[cadillacmike68]

I posted the full story on my earlier rod bearing failure thread.