head gaskets

Copper head gaskets leak oil around the pushrod tunnels. I've annealed the copper, used sealer around the tunnels, prayed to the Norton gods, and they still leak oil. I can't stand it.

Flame ring head gaskets tend to blow out. I've burned two of them.

Why has no one made a head gasket that seals well and doesn't blow out? The stock 850 doesn't have a whole lot of compression and I can't understand why the factory gasket doesn't hold up.

Grrr. Just venting...

Dave

maylar said:

Copper head gaskets leak oil around the pushrod tunnels. I've annealed the copper, used sealer around the tunnels, prayed to the Norton gods, and they still leak oil. I can't stand it.

Flame ring head gaskets tend to blow out. I've burned two of them.

Why has no one made a head gasket that seals well and doesn't blow out? The stock 850 doesn't have a whole lot of compression and I can't understand why the factory gasket doesn't hold up.

Grrr. Just venting...

Dave

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Have you been using the latest flame ring types? I just rebuilt my head and used whatever gasket Old Britts currently supplies. It was a grayish-blue colored thing with silver (aluminum??) rings around the cylinders. I've run the bike twice now with a head retorque in between and so far, so good. I will probably try retorquing again at 100 miles or so. I recently rebuilt a Matchless G12 and used a similar head gasket. I was warned by the Matchless gurus that several careful head retorques would be necessary to prevent the gasket from blowing out. I went to this type of gasket on the Commando because the copper one leaked like a sieve!!

I used to have good luck with copper by grooving the critical holes to hold sealer.

Have never had a problem with the 4-5 flame ring gaskets I've used over 35 years but a few re-torques are a good idea. Years ago I gave the copper gasket a couple tries with the annealing, mumbling prayers to Lord Castrol, etc but it always leaked badly. This is on a combat 750. The copper gasket (all taped up) is now used to mask the cylinder area when painting the barrel.

Russ

When useing a flame ring gasket would some gasket sealer of some kind be used? I too have problems here. :x

Nortasaki said:

When useing a flame ring gasket would some gasket sealer of some kind be used? I too have problems here. :x

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I painted a thin layer of Wellseal on the cylinder and on the gasket around the pushrod tunnels to try to get a good seal there. Other people will use a light smear of various silicone-based high temp sealers but you need to be careful with that stuff as it can clog your oilways. I am not sure the Wellseal will do me any good as it may just melt out of there. However, it made me feel like I was doing something! Seems like most people here feel that the composite gaskets seal the pushrod tunnels better than the copper. I had a pretty good leak from the pushrod tunnels as well as up one of the front studs when I had the copper head gasket fitted. It's still pretty soon after my rebuild but my top end is oil-tight so far!!

This is one of those issues you'll get lots of input on. Most guys figure out a setup they know works and go with that.
If possible I go with the gasket manufacturer's reccomendations as the latest version of gasket often differs from the specs that went out into the shop manual. Subaru, for example, has had three revisons to the 2.5 engine head gasket that i know of. An aftermarket maker may have different directions for thier product.
On something this antique which has quite a number of different gaskets available I'd buy from a reputable place (I use Raber's since it is nearby and they are very helpful) and use exactly what he says he uses.

Any other way you are doing the development. When I was in college I rebuilt my Commando using Atlas jugs which have to have the top milled flat. I made my own head gasket out of thick copper and had it off two or three times before I came up with scoring around critical oil passages and using sealer. These days I'm too lazy and just like to use a system somebody else did the work on.

Some folks will buy Ebay unknown gaskets and swear by spraying copper sealer or whatever and that's fine if you don't mind going back in. I mostly do stuff just once these days unless I forget the painful lessons I've learned.

hi maylar, sounds like you,ve had a few problems with head gaskets,could your problems be elsewhere,maybe the head is slightly warped,another thing to look at is are there any bolts or studs ,nuts bottoming out preventing proper tightening ,i must confess i,ve never used a torque wrench on any norton head iv,e had ,never blown a gasket ,allways used copper,had a weep now and again but not leaking like a sieve,i dont know what gasket is on my mk2 850 cos i havent had the head off yet but it does,nt leak and it has,nt blown

I used the Permatex copper loaded Spray-A-Gasket on both sides of the head gasket the last few times. Just a very thin coating should do it. I mask around the small oil drain hole about 1/4" when spraying to keep it from squishing out and blocking the passageway. I haven't had a problem with it not lasting.

There were some bad flame ring head gaskets that were around '80s and '90s and may still be with us. I think they were Domi-Racer made in Taiwan ones. I generally try to stick with Andover Norton directly or thru their USA dealers.

I use a copper gasket on my 750 racer. It would always weep a little, but then I heard about spraying it with some silver paint. Any old silver touch up paint seems to work.
Spray it on, not too thick, and let it dry. then assemble.
Worked for me.

I'd forgotten the silver paint trick, a bunch of guys swear that one works.

My friend has a big steel surface plate onto which he glues a fairly coarse (my guess is 100) sandpaper and he laps both the head and the cylinder top, so far he hasn't seen one that didn't need to be lapped. I'm sure that helps in sealing properly.

Jean

I have a marble plate on my workbench for the same purpose Jean, my wife found it in a thrift store.

Going off at a slight tangent, the two front studs on my barrels, No. 9 & 10 in the tightening sequence, do break through into the pushrod tunnels. If your studs break through (I am not sure if they all do), it is a good idea to seal the threads as oil can creep up the studs, and it can add to, or look like the head is leaking.

I blew the original head gasket installed by the factory when the bike was only a year old (racing a Sportster :wink: ). I replaced that with a copper one and it was fine for 30 years. Then I did some engine work a couple years ago and used a new copper gasket. It leaked oil out the front no matter what I did. Put a flame ring in there and it blew after 2000 miles or so.

This time the head has been professionally surfaced, so maybe I'll get a better seal and not toast the gasket. My flat plate for lapping the cylinder surface is a 1/2" thick piece of plate glass.

For a one or two time use, thick MDF could be used as a flat plate to lap a few pieces.

Jean

Plate glass also makes a great lapping surface. Everytime i asemble anything that is supposed to be flat I use my marble plate. Usually I only go down to about 220 grit to leave a little teeth for the sealer. On old bike parts I seem to rarely find much that is still flat after 40 years.