Anyone had flame ring head gasket problem?

I have had the head off and back on and off again twice tonight.
First time I refitted it , drive side exhaust rocker was holding the valve open, even without the adjuster removed, and no matter what position the crank/cam etc was in.
I quickly pulled it off again.
The last time I refitted it, turning the engine over by hand after setting torques, I did the valve tappet clearance, .011" as PW3 cam, and the spun it over a few times, when a couple of almighty bangs, exactly the same as when a pushrod is not seated on the end of the rocker. I know this sound and spent a lot of time making sure they were correct as don't want to make that mistake again. the only different item was a new head gasket. I checked the followers were free as turned motor over with pushrod in barrels but no head and everything bobbed up and down as it should. I compared the new gasket to old ones and they look same, was fitted correct way up and was torqued to spec (30/20 lb/ft)
Anyone had a similar experience?

I wonder if the pushrod was seated correctly? It took me several (!) tries to get it right. Each time I'd look and think the pushrods were in the right spot and then they weren't. For me the exhaust ones were the most troublesome.

That bang was the pushrod. I heard that one too.

Just fit the center bolt on the head to check to see if the pushrods are seated correctly.

Are you wondering if it's the gasket causing your consternation? I think it's just the wayward pushrods.

Is that a higher lift cam? Head skimmed? Valve hitting piston?

htown16 said:

Is that a higher lift cam? Head skimmed? Valve hitting piston?

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Yes, its a higher lift cam, and head has been skimmed with oversize inlet and exhaust valves, but I haven't touched them. I only took head off and everything from there down stayed the same.

A cam that’s not correctly spaced can partially lift the wrong lifter and let go with a bang.

But as your bottom end was working fine, this is unlikely.

Depending on how much you tried to ‘force’ the head down on that RH ex valve, you may have bent a valve. A bent valve can stick, and let go, also giving that bang.

I can’t think why the head gasket could be causing any of this personally.

You’re using Maney barrels, is that correct?

What pushrods are you using?

Fast Eddie said:

A cam that’s not correctly spaced can partially lift the wrong lifter and let go with a bang.

But as your bottom end was working fine, this is unlikely.

Depending on how much you tried to ‘force’ the head down on that RH ex valve, you may have bent a valve. A bent valve can stick, and let go, also giving that bang.

I can’t think why the head gasket could be causing any of this personally.

You’re using Maney barrels, is that correct?

What pushrods are you using?

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Yes, Maney barrels and pistons, standard pushrods adjusted for reduced height

What did you do re tappet clearances?

I see you wrote you set at .011” clearance. Is that the standard figure for a PW3 cam?

You may already be aware, but you may not... Maney advises clearances are halved as per cam makers normal instructions when using his alloy barrel with alloy pushrods (‘normal’ clearances would be for an iron barrel).

A head gasket can clash and rub against a pushrod, so look for witness marks on pushrod and gasket at the pushrod holes, and the head pushrod tunnels.

Fast Eddie said:

What did you do re tappet clearances?

I see you wrote you set at .011” clearance. Is that the standard figure for a PW3 cam?

You may already be aware, but you may not... Maney advises clearances are halved as per cam makers normal instructions when using his alloy barrel with alloy pushrods (‘normal’ clearances would be for an iron barrel).

Click to expand...

.011" is the tappet clearance I was advised for the cam, and do not remember any advice from Mr Maney6 to halve the clearance for alloy barrels. I have the scant "instructions" that came with the barrels and pistons and no mention in there.

Then you might wanna read this:

https://www.accessnorton.com/NortonCommando/maney-tappet-clearances.28073/#post-425690

Fast Eddie said:

Then you might wanna read this:

https://www.accessnorton.com/NortonCommando/maney-tappet-clearances.28073/#post-425690

Click to expand...

Cheers, I think a little further research is required. Maybe if it all goes back together without problems I will get a gnats chuff more power as the valves will open earlier!

kommando said:

A head gasket can clash and rub against a pushrod, so look for witness marks on pushrod and gasket at the pushrod holes, and the head pushrod tunnels.

Click to expand...

I looked and there was no great marks on them, however when I placed the gasket back on the barrels there was a little overhang on the front and to the outside of the engine. To be overly cautious I used a round file and a lot of frigging around to remove a little gasket to clear the tunnel. Not that its been a problem before...