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Late Navigator head gasket


I’m well on my way with my Navigator engine rebuild and have come to fitting the heads.   I’ve done the job several times before but hit a mental blank this afternoon.   Mine is a later engine and the heads are spigot-less.   I have sourced an original head gasket for the later engine and prefer to use that rather than the solid head gasket the NOC sells.   As you can see even though the head gasket set is for the later engine the head gasket is designed to fit spigotted heads.   The old gasket which came off the engine  was the same and never gave any problems.  Am I safe to assume that this will not be an issue?   The solid copper head gasket from the NOC shop is the same fit.   My notoriously fickle memory suggests the flame rings face upwards towards the heads.   Can someone confirm that is the case?

Thanks for the advice!   Nick


Hello Nicholas, my earlier navi has spigots and firstly I used a composite gasket which did not seal properly and caused some blow out at the right cylinder head.You can see the squished part between the cylinder heads.

composite gasket

I then used the solid copper version. I annealed it before and cut it into two halves. I had no problems since.

copper gasket


Hello Nick,

I can only speak from my own experience. After 3 years and 16000 miles with a later spigotless Nav and 8 years and 15000 miles with an Electra.

I have never used a solid copper gasket.

Mount gasket as your photo.

Light smear of Hylomar around pushrod tunnels.

Tighten head nuts progressively to 15 ft lbs. Always start tightening sequence from outside nut per Norton Twins manual.

No stretched studs. Check all 12 nuts run freely down 5/16 cycle threads to bottom.

I've had blow gaskets like Ulrich but always because I have not re-torqued the head after running. Or have pulled down the nuts that are visible and ignored the difficult ones. My advised intervals will seem ridiculous to many, but based on my experience.

Re- torque at 60 miles.

At 250 miles

At 600 miles.

At 1500 miles.

And annually.

I get through a few rocker cover gaskets. 

The clamping pressure on the spigotless head is considerably reduced because this later head is machined back further and the machined flat region between pushrod tunnel and bore is much greater than with spigotted heads. Something to consider before embarking on solid copper gasket route.

Depends on you confidence with a file. On my Electra I filed the flat surface on the alloy heads between pushrod tunnel and bore back about 20 thou to increase clamping pressure to rest of gasket which is sealing cylinder and pushrod tunnel.

For the Electra I use composite Jubilee head gaskets. You can also use these on your Navigator if you get stuck. The bore is just right for a (spigotless) Electra.

These are tricky engines aren't they.



Hi Ulich, Dan and Peter,

Thanks for all the sage advice - I have a solid copper and original 'late engine' composite head gasket so on balance I have decided to use the later with a smear of Hylomar as Peter suggested.   I will keep the solid copper one for future use if needed........I can live in hope it won't!   Having had everything vapour blasted and cleaned all the threads and using new nuts and washers it went together very smoothly and it was very satisfying torquing it down in the right sequence in 5 ft/lb steps to 15 ft/lbs.    The next step is to sort out a very frustrating gearbox problem.....stand by for a new post!   On a more cheerful note my spray shop are close to finishing the tanks and mudgaurds in as close as we could get to 'polychromatic blue'......I will post some pictures when I pick them up!

Tip top!  


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