Chevy Tri Five Forum banner
1 - 16 of 16 Posts

·
Registered
Joined
·
1,036 Posts
Discussion Starter · #1 ·
Just looking for some tips on cleaning the piston deck etc for the heads which are coming back from the shop soon. Anybody got some advice for prepping for new gaskets/heads? Engine is in the car this is a top end rejunvenation.
 

·
Administrator
Joined
·
70,795 Posts
You just need to make sure that both faces of where the gasket makes contact is clean from grease, dirt etc.

Depending on what gasket you purchase follow the manufactures recommendations.

I removed a copper gasket that had plenty of compound with a Felpro that needed no compound.

Later model heads have guide pins to help them sit on the block, if you do not I would recommend that you use some head bolts, cut the head off, slot it so you can use a flat screwdriver to screw them in & out.
 

·
Registered
Joined
·
2,231 Posts
I'd wipe down the cylinder decks with lacquer thinner, and then clean out the head bolt holes with a thread restorer. Afterwards you should be able to thread the head bolts in by hand.

Since the decks have not been recently machined, I'd use a composition head gasket. I like the GM gasket that's .028" thick, but it's really a function of quench height, which is a subject unto itself. If quench height isn't a concern, a basic Fel Pro .038" gasket will work fine. Sealant is typically not required unless deck or head surfaces show a little corrosion.

Some say you should use sealant on head bolts that go into the water jacket, but I have never had coolant leakage (that I know of) under a head bolt.
 

·
Registered
Joined
·
38,740 Posts
The composition gasket will seal better, but unless the deck height without the gasket is small, you're giving away both quench height and compression ratio. If it's a 265/283/327 (and some others) it came with a thin steel shim gasket. A lot of guys put them down, but they will work best if you're not modified for the thicker gasket. You do need sealer on a steel shim gasket, I like to use Permatex Hi-Tack spray or K&W Copper Coat spray.

Usually all you need to do is get the surface clean. Inspect it for previous trouble.
 

·
Registered
Joined
·
1,036 Posts
Discussion Starter · #5 ·
It's a 283 original and had steel gaskets on it. I will take one in when I buy the new ones. I think I will use the GM steel with GM gasket sealer, and I might as well use bolt sealant I think. I might do a light scrape with a plastic scraper vac out the piston tops and wipe the deck with with some kind of solvent.

Now I gotta kick the machine shop rear end to get them done - it's been too long they have been fluxed and are good and I need them back asap, summer's a wasting. Now I gotta remember how to find tdc.
 

·
Premium Member
Joined
·
7,710 Posts
Sealer

In the days before good gaskets we used the stamp steel model with aluminum spray paint. On one engine I used too much paint( dripping wet) . At a track 80 miles from home someone pit up the money for a teardown and they couldn't get either head off the block even with a crowbar. But like mentioned earlier thread cleaner, and some ARP thread sealant will get the job done. The guy who tore us down got embarrassed when we took off the valve covers and he saw the stock rockers (he was using Crane Gold rockers). After that he became a good friend.
 

·
Registered
Joined
·
872 Posts
I'd wipe down the cylinder decks with lacquer thinner, and then clean out the head bolt holes with a thread restorer. Afterwards you should be able to thread the head bolts in by hand.
Be sure that you chase the threads with a thread Chasing tap not a standard thread cutting tap. The latter will give you threads oversize for your purpose resulting in poorly fitting, i.e. loose, head bolts.
 

·
Registered
Joined
·
1,314 Posts
I like to clean the deck with a small hand wire brush to make sure the gasket sealant is sticking to metal, rather than previous gasket or sealer. I use Copper Coat spray. It will fill any small imperfections in the deck. Copper Coat is so good it sealed up my head gasket for a few months without the head being torqued. I was working late and forgot that I hadn't torqued the head bolts. It finally leaked water and when I took it apart I found the bolts weren't tight. Copper Coat is good stuff.
 

·
Registered
Joined
·
38,740 Posts
On the question of whether to use sealer on the bolt threads or not, usually they won't leak. I've even seen them leak and then quit after a heat cycle.

But consider the risk vs. the reward. Putting the sealer on initially is a small job. Putting it on later is a huge PITA that you didn't have to do.
 

·
Registered
Joined
·
1,036 Posts
Discussion Starter · #12 ·
I like to clean the deck with a small hand wire brush to make sure the gasket sealant is sticking to metal, rather than previous gasket or sealer. I use Copper Coat spray. It will fill any small imperfections in the deck. Copper Coat is so good it sealed up my head gasket for a few months without the head being torqued. I was working late and forgot that I hadn't torqued the head bolts. It finally leaked water and when I took it apart I found the bolts weren't tight. Copper Coat is good stuff.
When using this spray sealant do you cover the pistons and other areas of the block? I imagine you must. Or do you just spray the gasket directly both sides and put it on?
 

·
Registered
Joined
·
38,740 Posts
When using this spray sealant do you cover the pistons and other areas of the block? I imagine you must. Or do you just spray the gasket directly both sides and put it on?
Spray the gasket only. Go outside and do it to avoid overspray if your shop is close quarters. Let it dry 5-10 minutes and install it.
 
1 - 16 of 16 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top