Off with the head (again)

Well my method of putting some loctite 510 around the pushrod tunnels did ot seem to work so well despite several retourques. Head is flat though this is getting rechecked again, but I did find the front two cylinder head nuts on the loose side, all other bolts and rear nut stayed tight. Once everything is confirmed I am using the plaibond method that Jim Schmidt uses, hopefully no more leaks after that.

how are you confirming flatness?

jontg428 said:

but I did find the front two cylinder head nuts on the loose side, all other bolts and rear nut stayed tight.

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This can also be a symptom of the studs slowly pulling out of the head. Happened with me.

While not an expert by any means, I have had good success using properly annealed copper head gaskets, (I also like permatex copper gasket sealant). However, that said you might wish to try using a composite head gasket instead, (works great on my 850 Commando).

Looks like your problem is the head was loose so you had blowout past the head gasket fire ring
What retorques did you do at what mileage?

I just did my first rebuild and retorqued after 200 miles and was surprised how easy the bolts were to back off.
I marked the visible ones and when retorquing it was clear that the gasket had compressed with heat cycles

It is my first air-cooled engine so I figure the temperature range contributes to the need for retorque.

When I did that first retorque I did 2 foot pounds more than needed as I know that my next retorque will be soon and the gasket is
clearly compressing over the heat cycles

You did say you did retorques and my only suggestion to narrow the interval between them, especially after the last one.

As for the studs pulling out of the head possibility, I think the metal is too tough but it is an idea to check that the threads in the head are not compromised.

I had my head very lightly shaved because it was clear that over the years since the bike was made, the studs had pulled up the metal around them a little bit. (The machine shop pointed that out to me.)

Dennis

In addition to the head, the barrel deck might need to be surfaced. To me, not particularly anyone else, the pics indicate that the the head or deck are not flat when joined together. Pliobond will not fix surfaces that need to be resurfaced. Nothing will in my experience. A composite gasket can be more forgiving than copper, but I think one would blow out in your case if you didn't ensure those surfaces were flat before putting it back together again. I don't think 510 can take the heat on the exhaust side of the head. It gets over 450 degrees on that side of the combustion chamber. It might work to seal the crank cases together, but I wouldn't use the stuff period. Always seemed like I was trying to seal up a joint with Jello when using 510.

By the way, if the head was flat when you put it together last time, it probably isn't anymore. Just saying.

Ensuring the deck and head surfaces are completely flat makes a huge difference performance wise with a Norton engine. It'll be a different engine from one with a blown head gasket if done right. I've done it wrong a few times in my youth. Cutting corners to get something done sooner when building engines never plays out well.

Pliobond will definitely work with a copper head gasket if both the deck and head surfaces are flat. Pliobond is a great sealer for high compression engines. Permatex spray on Copper Kote is easier to work with and would be adequate for any stock compression built engine. Your pistons look very stock to me, but I could be misinterpreting the pics you posted.

zotz said:

This can also be a symptom of the studs slowly pulling out of the head. Happened with me.

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This.

What zotz & concors said , Also the head and the cylinder faces may need to be surfaced. Andover recently told me their copper head gaskets are not annealed. My supplier did sell annealed gaskets and they were softer and had a perfect, nice copper surface appearance, ( like a non annealed one would.) Did anyone mention sealing the 2 5/16" studs sticking out of the barrel?

Before you invest all the time, effort, expense, to machine the cylinder head surface, and or machine the top of the cylinder barrels, you must FIRST confirm that those two studs are not pulled, and are indeed clamping with the force as designed. What you describe is the exact same symptom, and feel on the wrench that I had when my two front studs were pulling.
Let's not make a space shuttle when all we need is a grocery cart.

Annealing copper head gaskets doesn't work because the copper doesn't crush at all - measure a used copper head gasket and check for yourself. Composite gaskets crush here and there and then your head warps.

Coppercoat spray loses adhesion at 400F
Pliobond loses adhesion at 500F

Carl H said:

Did anyone mention sealing the 2 5/16" studs sticking out of the barrel?

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This too! Caused me to have to redo my gasket