1954 NH - blown head gasket

[Gui.dorey]

Hi everyone,

My 1954 NH was running very well since the rebuild, but on my last ride and coming up to the first 500 mi service, I suddenly felt it loosing power. Luckily just a few miles from home and was able to get back. As it turns out, the head gasket blew around the front right corner.

The head bolts were torqued down according to the manual. Anyway, I just wanted to ask if it is a common thing as I haven’t heard anyone mention it on an NH, or just my bad luck.

Cheers
Gui

[Simon.Gardiner]

Hi Gui
I assume you've got the later-type cast-iron head with the copper gasket?
I'd say you've been fairly unlucky to blow it that badly, in my experience they usually just blow a lot of oil when they go.
I'm afraid I used to be guilty of ignoring any official torque figures and used the proverbial 'effing bloody tight'.
It may help to grind the head and barrel joint (with grinding past, a bit in the manner of what's done with the earlier head and barrel that don't use gaskets) to check that there are two good mating surfaces - although you may have already done this.

HTH

SG

[Gui.dorey]

Hi Simon,

The head is cast iron, but the gasket on my engine is paper, not copper.

[Simon.Gardiner]

Cylinder base gaskets are OK with paper but I've never heard of a paper head gasket before!
The head gasket should be copper as per:
https://draganfly.co.uk/shop/78293/head ... -nh/#79-52

SG

[JohnnyBeckett]

hi the paper gasket goes under the base of barrel and the copper gasket goes between the head and barrel just check the faces on the head and barrel that they are flat you can use a little bit of engineers blue on the faces to see if they are flat

[Gui.dorey]

Hi
Maybe I’m confused and it is a copper gasket. Can’t remember anymore. I’ll check when I open it up.