Copper Spray on OEM STi Head Gaskets?

I have some slight imperfections on the deck surface on one side of the block. I've had a couple old timers say to use copper spray to help seal the imperfections. I want some more opinions. The only reason I'm not getting it redecked is that I cannot afford it. The heads are machines and ready to go, but the short block has some slight imperfections. Use the spray, or will the OEM gaskets seal good by themselves?

 

Any help is appreciated.

Sgt.Gator suggested copper spray as a means to fill in slight imperfections. more discussion here - http://legacygt.com/forums/showpost.php?p=5312244&postcount=1094

I was planning on doing mine. Last couple head gaskets Ive done worked out great with it.

Yep, copper spray is old school hot rodder. Still works though.

 

Clean the new HGs off really well. You want no oil residue on them, even the slightest bit will make the copper spray goofy.

Spray both sides of the HGs.

Will it work? Maybe. There's no way to tell how bad your imperfections are without a measurement.

 

Did you put a precision straight edge on the block and measure? If you are out of spec you will probably fail.

 

There are ways you can clean your shortblock and prep it to remove most of the imperfections.

 

Don't use a whizzy wheel, although that's what the dealer uses on heads. I've watched a dealer do it.

 

Here's video that should help on the prep.

 

Of course you have to plug all the holes so no grit goes down in the block. And when you're done you should spend a lot of time cleaning the inside of the block, or pay a shop to do the cleaning.

Okay thanks! The heads will be straight. They're off getting a valve job. The deck surface has a few small imperfections mostly visible. But there are a couple I can feel with my finger.

Other than those the deck is straight.

Okay thanks! The heads will be straight. They're off getting a valve job. The deck surface has a few small imperfections mostly visible. But there are a couple I can feel with my finger.

if you can feel them with your finger, your deck is not flat.

 

take a straightedge, hold it vertically against the deck and shine a flashlight against one side. If you see light on the other side, you need to fix the deck. Otherwise the gasket won't seal.

im thinking he means there is a chip or something in the deck and he can catch a nail on it. i will be subscribing for the answer.

The copper spray is a great way to add complexity with zero tangible benefits. Quality head gaskets like OEM and Cometic do not need to be sprayed. That being said there is no harm other than the added prep, cost, and mess. I sprayed a few sets about 10 years ago and never had any issues, but haven't sprayed any since then and never had a car come back with a HG leak.

On the last couple cars I did, one had the head rebuilt, the other was just slapped back together. Was easy to justify the copper coat and neither had an issue for many miles, one at 28psi (Evo).

 

Now that I'm assembling a new sb and resurfaced head, I'm doubting whether I actually want to take the risk. Heads are going on this weekend. Too much or uneven and its going to cause problems. Analysis paralysis.

I'm not sure why people insist on spraying coated MLS gaskets, but it's your money not mine.

It's basically a very small scratch that I can just barely feel. The deck is flat. There are just that imperfection on it.

I'm not sure why people insist on spraying coated MLS gaskets, but it's your money not mine.

 

Hm. I didn't think the OEM Gaskets were coated

The copper spray is a great way to add complexity with zero tangible benefits. Quality head gaskets like OEM and Cometic do not need to be sprayed. That being said there is no harm other than the added prep, cost, and mess. I sprayed a few sets about 10 years ago and never had any issues, but haven't sprayed any since then and never had a car come back with a HG leak.

 

Agreed. The copper RTV is great for exhaust flanges and such but I'm skeptical if COPPER SPRAY really adds any benefit for a head gasket.