Reinstalling the Head

Hi,

I will be reinstalling the head on my 1973 850 after a gasket change (this is my first time) and I assume that stud # 2 (back) and studs # 9-10 and also #7-8 must be in place before I put the head back? Will there be enough clearance since I removed the head only?

Also, do we first screw the studs in the cylinder at about the same torque as required for the head?

Lastly, do we lubricate studs and bolts with oil, antiseize or something else?

And no gasket sealant on a flame ring (not copper) right?


THANKS

SGOUD said:

Hi,

I will be reinstalling the head on my 1973 850 after a gasket change (this is my first time) and I assume that stud # 2 (back) and studs # 9-10 and also #7-8 must be in place before I put the head back? Will there be enough clearance since I removed the head only?

Also, do we first screw the studs in the cylinder at about the same torque as required for the head?

Lastly, do we lubricate studs and bolts with oil, antiseize or something else?

And no gasket sealant on a flame ring (not copper) right?


THANKS

Click to expand...

Three studs in the head and two studs in the cylinder should be in place before fitting the head. If the engine is in the frame the trick to getting the head and pushrods to clear between frame tube and cylinder is push the pushrods as far as they will go into the head cavity then slide in the whole head assembly sideways stopping above the cylinder. Let the push rods drop into the cylinder tunnels then let the head down a bit. Look in through the exhaust rocker covers and with a screwdriver or other slim tool align the push rod cups with the rockers. Once that's done let the head drop as far as it will go. Install the allen bolts and start snugging the head down. Add the remainder of the nuts and bolts then torque to the pattern and setting recommended in the shop manual. It takes some good manual dexterity to get the pushrods in place...good luck.

Ugh, I mean hehe, yes lots of dexterity required to get push rods
up beyond the rocker ends to gain just enough clearance to
slip head in under spine. It can take me an extra hour just
to get the right combination of shove jiggle hold twist release
and can't say that I've ever found the right combo on purpose,
though have been fooled once of twice to have just slide
right up, but I let em go and the puzzle started anew.
BTW if you ever have rockers out grind off some the area where
push rods must pass and head switch in/out become 15 min
task if you take your time.

Shop gem for me is to zip tie the head up on two bolts stuck
in the head steady threads. This holds head up to diddle
gasket &/or sealant [none on flame ring if seals right]
and aim release the push rods to enter their tunnels.
Oh yeah zip ties around each set of shoved up hi push rods
helps wedge them up and handle them separately later.
Otherwise 4 rods at odd angles trying to fall skewed into
tunnels but for one or two that just don't, so must retreat and repeat.

I've like to get rubber bands [link up small ones] to stretch
over each side of the head to hook on intake and rocker arms
to hold them nicely down on each push rod as seated so it stays
seated while doing the others.

Remember which fasteners are smaller ones for a tad less severe
torque than bigger ones.
After joyous noise and heat, immediately on shut down
back off fasteners and re-nip till it almost hurts. Repeat
as many times as needed soon as possible to crush gasket
down good and stay weep free.

hobot

It's a PITA.

I had mine on good, then couldn't figure out why I had no clearance on one of my valves.

Fortunately, I was able to push the errant pushrod into place at the top with a screwdriver - with a very satisfying "SWACK" as it came home.

Others are more skillful I'm sure. As I will be, I hope, in another 20K miles or so when I do the rings again...

I like to use a little antisieze on the studs and nuts (and the exhaust nuts) and a smear of RTV on the gasket around the push rod tunnels. Make sure that the gasket does not overlap the push rod tunnels.

It doesn't sound like you have a manual. If not, one would be very helpful getting the tightening pattern right. Most of the nuts and bolts are torqued to 30 ft-lb. The two in front, on top (5/16" studs) are torqued to 20 ft-lb.

Greg

If you haven't done this already, dropping the engine by pulling the front isolastic through bolt will give you a couple more inches of room to play with. I understand it's possible to do it without this, but I've never tried it. You'll need to have the frame supported when you do this. The centerstand won't work, unless you have one of the early frame mounted centerstands. I have a support that I made from two 4 x 4 pieces of lumber nailed together nailed on top of a piece of wood that's about 3/4" thick. Just the right height to push under the frame while the bike is on the centerstand, then push the bike off the centerstand, and the wood holds up the frame.

-Eric

That is a good tip, but at least for me, the issue was less room to maneuver the head in - which wasn't really difficult although I know I had a few back and forth "tip-ins" before I got the angle right - as getting the pushrods aligned, which seems more art than science. Or more experience than anything else, I'd wager. I'd bet Mick Hemmings spends a lot less time "per" than mere mortals such as me.

Loctite or thread sealant on the 2 front studs were they screw into the barrel casting, it should stop oil weeoing up the stud from the push rod tunnels

I put just a tad of sealant of choice around the push rod tunnels and RTV on bottom of the top front two nut. Torque to specifications 2 or 3 times stone cold along with exhaust nuts. I made the mistake one time of re torquing one more time after a couple weeks and the RTV on the front two studs started leaking :roll: and had to remove them and redo the RTV treatment! No more leaks :mrgreen: as a matter of fact I have no leaks! :mrgreen: :mrgreen: :mrgreen:

Hi there,
I helped my mate put the head back on his 850 last monday evening.
Its a lot easier with a friend holding the head off the barrels while you locate the pushrods top & bottm.
Get a torch to see in the exhaust rocker hole to locate in the tappets. the inlets are hidden behind the exhaust rockers but you can just see them if you look closely.
Once located in place put the 4 outer bolts in to keep head just in place & turn over slowly to make sure all 4 valves open & close then just tighten down slowly.
Yes its fiddly but much easier with a friend helping.
Just make sure you have slackened off the tappet adjusters if you have disturbed these as if over adjusted the valve might hit the piston & damage somthing.
Also be careful not to damage or scratch the head gasket when you slide the head in place & locate on studs.
Its actualy quite an easy job.
Have a can of beer ready for you & your mate once the job is done.
Cheers Don

Don Tovey said:

Get a torch to see in the exhaust rocker hole to locate in the tappets.

Click to expand...

"Torch"

That's definitely another item I need to add to the US = UK lingo list!

Flashlight-US = Torch (battery-torch)-UK.

Hi all,
sorry I should have thought of that. (Torch = Flashlight)
And for you aussies have a tinny ready.
Did you know that Durex in Aus is sellotape. (Thats not installing a norton head)
That could get you in a sticky mess & your wife in an even worse state.
Cheers guys, Hows it hanging ?

Hope I dont get banned !

Gday Don, that can of beer is the 375 ml spanner. How they hanging?? Well, I prefer if theya swinging!! (lol)
Foxy

After all the cussing and cursing and the head is on and the pushrod are seated in the rockers, you need to check , double check and re-check again and again that all pushrods are in the rockers as you bring the head down to the gasket with the fasteners,

A simple, but infinitely effective method of installing the head involves taking a lint-free disposable shop towel and tearing it in half.

Turn your head upside-down on your workbench, insert the pushrods in thier respective holes, then roll and stuff each tunnel with half a towel, with the tails pointing clear to each side.

Set the head in place, a bit of a jiggle, lower away, then extract the towel bits. Done and done.

95% success rate in under 2 minutes in 20+ attempts. (first attempt used too small of towel bits, too loose)

It really helps to have a helper .. one person on each side.. when seating the pushrods. Here's a tip that makes it a lot less frustrating to keep the pushrods in place as you go from valve to valve - tie the rockers up with rubber bands:

GREAT TIPS, I WILL USE THEM ALL!!!


Just to be sure :

A) Locktite (Blue) on the 2 front studs in the barrel casting

B) Sealant (spray) around the push rod tunnels on both sides of the gasket

Is it ok with that???

All the easy tricks on none at all needed with head on bench and/or
upside down, it when on top of engine under frame handling the
push rods can be a testing swearing straining booger.

Trimming the rocker ends solves this but in mean time I like
idea of dropping the front iso as way less strain than fighting
the push rod puzzle.

You may consider yourself a mostly competent m/c mechanic once
initiated by handling Commando heads successfully, a few times.

I used to think of Nortons and cycles in general as a riding hobby,
but now realize its really a never ending battle of wits and finances
and fates and will power-desire, then can ride as nice side effect icing.
Rest of life stresses will be more tolerated and dealt with by
the toughing up on Commandos.

hobot


hobot

hobot said:

All the easy tricks on none at all needed with head on bench and/or upside down, it when on top of engine under frame handling the push rods can be a testing swearing straining booger.

Click to expand...

Using my shop towel method with the engine IN THE BIKE works perfectly.

Alas Paul I'll definitely be following your stuffed towel trick soon
enough on factory Trixie Combat as rockers not ground down.
Will have to read again to make usable sense to my dyslexic waves.
I'm working up nerve today to clear Norton Nest and organize tools to
face again, pensive tasks w/o screw ups, again, on engine assembly
flywheel to rocker covers and plug boots.

Got me various sizes textures rag pile to pick from.
Socks are by far most useful but tougher bigger jeans can
protect swing arm to forks from bug crap to knock overs.

hobot