Cometic MLS head gaskets?

[fe66comet]

I just picked op a set of Cometic MLS steel gaskets for my 445. The instructions state the deck needs to be a smooth, almost polished surface. Problem is there is some pitting around the holes where the water jackets are and the instructions also state to install on a dry surface. Can a little silicon be used around the holes? Or should I have the block touched up a little? Thanks .......Jon

[jayb]

If the gaskets have the black coating on them I think I'd just use them as is, unless the pitting is really severe.  You can also spray Cometics with copper coat to enhance the seal, although when they are new that is usually not necessary.  They are re-usable, and I'll usually use the copper coat if I re-use them.

[fe66comet]

They have the coating on them and all the deck looks good except the area around the large slots at the front and rear of the block. The pitting is definitely noticeable, I was just thinking about running a small bead around the water holes in the deck. The actually area that is pitted is the area where the gasket fell short or the hole in the head was larger than the one in the block.

[jayb]

I don't think it would hurt anything to put some sealer on the pits.  If the pitting is bad enough I guess I'd go that route.

[fe66comet]

That's what I thought but was not sure if it would disturb the the torque values or anything. They do have the raised rings so I was thinking of putting a little ink on the area and check if the pitted portion falls into the raised gasket surface.

[CaptCobrajet]

A little sealer there can help you.......too much can hydraulic the gasket and hurt you.  Not sure what kind of heads you have, but MOST aluminium heads need to have the two upper water holes tapped 3/8 pipe, aluminium square head plugs JB'd in there, milled back flush, and then the gasket transfer punched and the plug drilled the size of the hole in the gasket.  Usually when a Cometic seeps, it is those two water holes up by the intake flange running over into the embossment.  Just FYI you might look at that.

[fe66comet]

They are Edelbrock RPMs, with the layout of the holes they are smaller than the block holes so I am OK there I was thinking a 1/8 bead of ultra copper would do. Also torque immediately without set time would allow it to move better. I am using T&d bolts for the top and ARP bolts on the bottom as with my rocker system and heads studs do not work.

[Joe-JDC]

You don't want to put a bead that will squish out and enter the water system and clog any tubes in your radiator, or heater core.  If that pitting is bad, then fix the problem now.   JMO, but anything worth doing is worth doing right the first time.  Joe-JDC

[sumfoo1]

Again just trying to learn here but Cast iron is hard as crap to weld so i'm sure you don't want to do that in this situation right?

Would something like brazing silicon bronze or something into the holes work?

I mean does the new gasket even mate on this surface if the old one that caused the pitting from the water didn't?  I mean if there was no gasket there and there is no gasket there does it really mater or are you just trying to prevent further degradation?

[Joe-JDC]

I am trying to visualize exactly what it is you are saying.  If the pitting is not covered by the new gasket around the holes, then it is not a problem.  It does not need silicone on it.  If the pitting is under the gasket material, then the block should be decked smooth and square decked prior to the assembly.  If the pitting is so bad that decking the block will not remove it, then I would also consider whether the cylinder walls are still thick enough for a rebuild.  Look at the overall block condition, and determine if you want this to be a longterm rebuild, or a stop-gap build.  JMO, but I still contend that anything worth doing is worth doing right every time.  Joe-JDC.