Messed up head

I had been working on this bike for months restoring it back to it's original glory and everything has been great except for the head. I had all the valves and guides done, installed it and then after the first warm up the head started to leak oil from the third fin up front.
I took the head off because one of the front studs pulled and I assumed that was why the thing was leaking. Fine.
Got the stud repaired, head resurfaced and put it back on. No leaks, bone dry.
So, I did the warm up till hot, let it cool overnight, re-torqued the head, took it for ride of maybe 40 miles and then the next day re-torqued head and then went for a 4 hr ride.
Now it has a blown head gasket. When you blip the throttle you can see the leak shoot out the side between the head and barrel. WTF. Did I do something wrong?

If you own a Norton, you will have a messed up head, and god bless you for the straight line.

Guido,
I'm assuming the head and barrel face are flat.

Check every thread, nut, bolt and stud is clean and runs free. ( no need to check the fixed in stud threads, I always Loctite them in. )

Put the head on the barrels without the push rods and gasket and using your fingers only run each bolt right down finger tight. Any drag check out why, it's usually the alloy clearance hole has burred over. If so run a clearance drill down each hole, double check and try again.

Use a quality gasket such as Reins ( I think that's how to spell it?) Norvil and RGM sell them, others too I'm sure.

Now when you torque the head down you'll achieve a true and even clamping force.

Works for me.

Best of luck.

Cash.

ps I don't think Norton heads are that bad at all.

Guido said:

I had been working on this bike for months restoring it back to it's original glory and everything has been great except for the head. I had all the valves and guides done, installed it and then after the first warm up the head started to leak oil from the third fin up front.
I took the head off because one of the front studs pulled and I assumed that was why the thing was leaking. Fine.
Got the stud repaired, head resurfaced and put it back on. No leaks, bone dry.
So, I did the warm up till hot, let it cool overnight, re-torqued the head, took it for ride of maybe 40 miles and then the next day re-torqued head and then went for a 4 hr ride.
Now it has a blown head gasket. When you blip the throttle you can see the leak shoot out the side between the head and barrel. WTF. Did I do something wrong?

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Les Emery, Quote: "Torque head, warm up engine...leave over night, re-torque..get motor hot....cool and re-torque and dont use solid copper head gasket"....i have ..but heat treated it first...cherry red..and into water. No problems

+1 on the annealed copper. I did my 850 that way and when I tried to remove the head, it wouldn't. The annealed copper super sealed to the 2 trued surfaces. No Leaks, and that was only after 100 miles.

There are some things you can do that might help.

clean the mating surfaces with something that doesn't leave any residue, points cleaner, denatured alcohol
don't contaminate the surface of the gasket
use anti-seize on the nuts and bolts, put some on the washers too, goes double for stainless,
follow the tightening sequence on fig.C2 in the manual, the elongated nuts under the exhaust ports are last

I think the seal gets cooked on by the heat of the cylinder head along with the clamping force of the nuts and bolts. If you do 3 re-torques after just getting the engine hot without running it for hours, then letting it cool, you get the final crush on the gasket and the seal you need around the pushrods. I read someplace that there is a substance that is used on the gasket surface that acts as a sealer, the seal isn't entirely mechanical. But if you jump the gun before the crush is stabilized and the seal is established, then you might blow it. :roll: Then any re-torques to get it to seal probably won't work.

Well, Ill be ripping it apart again. So disappointing. I'm missing so real nice weather.
I'm a contractor so because of the nice weather I am having to work most weekends. Feast or famine, right?

I get the gasket from Andover. You're saying there is a better gasket?

The head was re surfaced but the barrel wasn't. The head has been surfaced 3 times in the past.
I think the compression is real high now. If I go and resurface the barrels just in case won't that really raise the compression?
Are there different thicknesses of head gaskets other than the copper ones to lower the compression?
I'll be CC'ing the head this time around and checking the deck height to determine the real compression ratio.
Are there different thicknesses of base gaskets? Raise the deck, lower the compression, right

I build Hi-perf VW engines as a hobby so I know my way around and engine but these Nortons are sure touchy

Make sure your threads are long enough to pull the head down on all the studs & bolts.
Might be worth resting the head on the barrels & seeing if you can get a thou' or thou' & a half feeler in between, to see if surfaces are flat to each other.
Lots of people use allsorts on head gaskets, I just degrease surfaces.
Used to use copper, but eyeletted now.

Guido, I thought the second episode was an oil leak like the first, so all that about the gasket sealing probably doesn't apply. It would be interesting to see what the actual compression ratio is. Could you cc the head? There is a way to lower the compression ration by adding a steel compression plate under the barrels.

I build Hi-perf VW engines as a hobby so I know my way around and engine but these Nortons are sure touchy

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Gosh that is so healing of words for me to read, implies it ain't just my stupidity having similar events as yours. There was a thread on Brit Iron list warning about substandard gaskets last couple years even from top of the line vendors, especially concerning the new flamering kind. Danger to run with gasket leak is two fold, one gas jet grooves in head and two can gas jet right through fuel lines. Most the failures will be at the oil drain hole which aims jets right at the factory fuel routes. i was able to solve my head jet push rod tunnel grooves by hi temp JBW razored level with the rest. It needs replacing after several removals but stays put otherwise, thank goodness.

Cherry red is not enough to soften Cu as much as Orange/yellow red and not water dunking just slower air cooling and careful handling of wax like state its left in. I didn't get as good of sealing using copper coat or copper or silver paint as I do Hylomar smear on both sides of copper gasket this time on Trixie Combat and two re-torques only.

All cylinders come from factory with a .003" slant, but its flat so don't hinder sealing. Sight increase in CR should not be noticed in detonation or sealing but can foul valves or mess with rocker contact geometry.

I had Timesets placed in Peels Combat head studs to take the torque better.

The head was re surfaced but the barrel wasn't. The head has been surfaced 3 times in the past.
I think the compression is real high now.

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You might want to consider claying the pistons if you have had much cut off the head. You might need to flycut the pistons for valve clearance. As Flo says make sure your head bolts aren't bottoming and there is enough thread on the studs as a result of taking off material from the head. My 850 cafe racer head has steel spacers under the head bolts. (Actually top hat spacers pressed into the head).

I like the idea of those top hat spacers, saves the ally becoming squashed.
Got to admit though, most supplied washers are soft crap.

I'm gonna cc the head when I get it off. Anyone know what the head should cc at stock and what the max allowance is?
I forgot to clean the head bolt bores in the cyl to see if they were filled with crud. I did clean all the bolts and studs. It never occurred to me that the bolts or nuts may be bottoming out from too much machining.
A VW engine is all studs to mount the head to the barrels. It's been awhile since I had to deal with head bolts.
And you're right about the quality of the gaskets, I had to return one cuz the flame ring crimp was all stamped wrong and this one came from Andover Norton and the maker of the gasket is Victor / Reinz AFM.
Now I know to ask to have the gasket completely inspected before being shipped.
I buy my parts or bits as some call them from Phil Radford of Fair Spares. Great guy.

For 750 its in the mid to upper 40's cc.

hobot said:

For 750 its in the mid to upper 40's cc.

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You'd think that would be of some help to me. Love your videos Hobit.