Norton Engine Build

Folks,

I'm new to the forum but not new to Nortons, I know a lot of you and you know me. So I thought I'd put together a little story about a recent engine build I did for a customer.

The customer is a pretty serious Norton addict but not capable of spinning his own wrenches. I'd done a lot of work on his bike over the last couple of years but his 1972 Combat engine was obviously really tired.

Pulled his engine, tore it down and noted that the Superblends fell out of the cases with no heat. Just fell out. So much for that set of cases.

I had a spare set of Mk. II 850 cases available, so those were sent to CNW for the breather modification.

Then I built the engine.

* Steve Maney crank

* Maney Stage One head, valves, springs

* JS Engineering pistons, rods, lifter blocks, lifters, pushrods, Stage One cam. Must say Jim is great to work with, always there to answer the silliest question.

• Balancing by Svint at Lindskog balancing. (What a perfectionist.)

• OldBritts ignition

• CNW FCR carbs and intake manifold, port-matched to the Maney head

• RMA cam chain adjuster (I know, controversial, owner's choice}

• CNW reed valve breather

• CNW hardware, all their new ARP engine bolts

• Lightened rockers and alloy adjusters (polishing out these rockers is a good excuse to pop a bottle of chosen beverage, what a chore.)

Got the motor built and back into the chassis, time was passing, winter coming on, owner wanted to ride it home (Whitefish, MT to Calgary, CA)

I fired the bike once, ran it 10 minutes, drained the oil (including the Lucas Oil rebuild additive) changed the filter, retorqued everything after letting it cool. Then fired it again, rode it a couple of miles, again drained the oil, cleaned the magnetic filters and changed the main filter, refreshed with Amsoil and Lucas Oil Zinc additive.

On my short ride I rolled the bike on in second gear and it nearly wheelied.

So the owner shows up, he fires the bike and he rides non-stop from Whitefish to Creston, Canada. There is a good vintage mechanic there, he retorqued the base bolts and head and checked all the valve clearances. The engine was pretty loose, in particular the cylinder base bolts were loose. The engine had a JS Engineering copper base gasket installed, with sealant...why would those base bolts be loose? They'd been through one round of retorque... Not sure what to make of that condition.

Then, the guy rode on to Calgary. He called me from home.

"I'm amazed. I think this bike is faster than my Ducati Hypermotard. I've never had so much fun on a motorcycle. This Norton is a better motorcycle than either of my Ducatis."

So, there's one guy's experience with a pretty nice Norton build. He's happy.

As the builder, I'm so appreciative of my support. Steve Maney, Jim Schmidt, Lindskog Balancing.

But the bottom line is, nobody ever said this was a cheap sport. You want to go fast on a Norton?

Chug a couple of Newkie Broons and get to work.

Total cost involved, my customer had about $7500 in this engine, parts/labor.

Skip Schloss

Hi Skip, there is a forum tradition... "without pictures, it didn't happen". :lol: We love mechanical porn.... :shock:

concours said:

"without pictures, it didn't happen".

Click to expand...

I was going to say...

Excellent stuff! As for the base nuts coming loose - were they and the studs stock items or stainless ones?

CNW ARP kit bolts, with anti-seize.

I think the ARP fasteners allow for higher torque specs. Matt isn't going to issue these specs (liability) but I think you can easily go to 35 ft/lbs with the ARP cylinder base fittings.

My thought is that using the JS Engineering copper base gasket is what causes the base bolts to loosen up. Not a condemnation, just a recognition that if you are using Jim's gaskets, as you should, you'd best plan on a couple of retorques.

Before the JS base gaskets were available, I used to just glue down the cylinder to the cases with Hylomar. Problem was, you could not keep the adhesive from covering the oil drain hole.

Using the JS base gaskets and adjusting for cylinder/head stack height is a better solution. You have to assemble the top end two or three times to check squish and valve/piston clearance but so be it. You can adjust all your clearances with Jim Schmidt's head gaskets, of variable thicknesses.

Skip

New to the forum, so now I have to post pics.

Soon. I need to gain learning.

Skip

I shouldn't matter if you have a metal base gasket or no gasket at all. Yamabond is my prefered choice for preventing leaks and you should always blow some air through the oil return hole to make sure its clear. If the sealer hardens up before clearing the hole then you can run some 1/32" SS wire through it to clear. You want to do this before you screw down the timing cover.

You would probably have problems with a paper base gasket. The paper pounds down and the bolts get loose. A metal base gasket (alum, copper or steel) isn't going to compress but it will still need re-torquing and so will a motor with no base gasket at all just because things must settle in.

The cylinder base bolts are always highly stressed and putting stronger bolts in might not make much difference because you can strip out the aluminum case threads even with the stock bolts. I have a basically oil tight motor everywhere but the cylinder base can still creep a little oil stain - even with no base gasket at all and Yamabond sealer. There is so much heat and vibration trying to separate the cylinders from the cases. I had to retorque a few times early on but not anymore.

Highly stressed race bikes can have problems pulling out the base studs and may need Time inserts (stronger than heli coils). This used to be a problem with Ron Woods flat tracker and he hipped me to using the time inserts.

A Commando on the highway can be geared too low and be revving higher than it needs and something like this will add unwanted stress and loosen things up. No need to be buzzing over 4000 RPM at cruising speed for hours. A 19 tooth sprocket is just wrong and you can run as high as a 22 or 23 tooth countershaft sprocket on a one up cruiser.

SkipSchloss said:

CNW ARP kit bolts, with anti-seize.

Skip

Click to expand...

Thanks - it wasn't that then! The reason I asked is that I'm curious as to how many of the reported Commando engine 'ills' are actually due to inappropriate stainless fasteners being used. Most of them are sold as 'stainless', without any reference to the grade used to manufacture them.

"So the owner shows up, he fires the bike and he rides non-stop from Whitefish to Creston, Canada. There is a good vintage mechanic there, he retorqued the base bolts and head and checked all the valve clearances. The engine was pretty loose, in particular the cylinder base bolts were loose. The engine had a JS Engineering copper base gasket installed, with sealant...why would those base bolts be loose? They'd been through one round of retorque... Not sure what to make of that condition."

The worry I would have here if this base gasket 'crushing' happens is this, if fitted to a later engine, with 'through bolt' barrels, they will also be loose, and impossible to tighten without removing the head.

So, are copper base gaskets best avoided on through bolt engines?

Fast Eddie said:

"So the owner shows up, he fires the bike and he rides non-stop from Whitefish to Creston, Canada. There is a good vintage mechanic there, he retorqued the base bolts and head and checked all the valve clearances. The engine was pretty loose, in particular the cylinder base bolts were loose. The engine had a JS Engineering copper base gasket installed, with sealant...why would those base bolts be loose? They'd been through one round of retorque... Not sure what to make of that condition."

The worry I would have here if this base gasket 'crushing' happens is this, if fitted to a later engine, with 'through bolt' barrels, they will also be loose, and impossible to tighten without removing the head.

So, are copper base gaskets best avoided on through bolt engines?

Click to expand...

From my research and experience no base gasket on 850s until the MkIII. According to the parts book there's none listed for the '73 750 either.

I've had good experiences with Wellseal - made in Preston, Lancashire (didn't know until today!)
I've also used Threebond which I believe is similar to, if not the same as Yamabond (couldn't find in the UK when I last looked), but Wellseal never sets, so is more tolerant when the joints require re-torqueing.

Broken link removed

When I removed the top end from my 850 last year the through bolts were still holding torque just fine, which was reassuring to me at least :wink:

B+Bogus said:

Fast Eddie said:

"So the owner shows up, he fires the bike and he rides non-stop from Whitefish to Creston, Canada. There is a good vintage mechanic there, he retorqued the base bolts and head and checked all the valve clearances. The engine was pretty loose, in particular the cylinder base bolts were loose. The engine had a JS Engineering copper base gasket installed, with sealant...why would those base bolts be loose? They'd been through one round of retorque... Not sure what to make of that condition."

The worry I would have here if this base gasket 'crushing' happens is this, if fitted to a later engine, with 'through bolt' barrels, they will also be loose, and impossible to tighten without removing the head.

So, are copper base gaskets best avoided on through bolt engines?

Click to expand...

From my research and experience no base gasket on 850s until the MkIII. According to the parts book there's none listed for the '73 750 either.

I've had good experiences with Wellseal - made in Preston, Lancashire (didn't know until today!)
I've also used Threebond which I believe is similar to, if not the same as Yamabond (couldn't find in the UK when I last looked), but Wellseal never sets, so is more tolerant when the joints require re-torqueing.

Broken link removed

When I removed the top end from my 850 last year the through bolts were still holding torque just fine, which was reassuring to me at least :wink:

Click to expand...

Me too Andy, I believe 850s did not have a base gasket. I have no gasket on mine and I used Wellseal and all is good.

However, copper base gaskets are often used by folk to adjust compression ratio and / squish band clearances on non standard engine builds.

So I'm wondering if this is a bad idea on through bolted engines ... ?

I'm not finding any variance between new and used copper head or base gaskets. There is no measurable difference in thickness. On a used copper head gasket the areas nearest the bolts measure the same thickness as areas mid point between the bolts. Annealing doesn't seem to make any difference either. There was a thread about this somewhere but I lost it.

Composite head gaskets on the other hand show compression and need several re-torques.

But there can be some settling in especially when sealer is involved. A high spot or speck of dirt may flatten out. I have had to retorque cyl base bolts (when racing) even without a gasket. So there is some adjustment going on - especially when heat is involved.

However, copper base gaskets are often used by folk to adjust compression ratio and / squish band clearances on non standard engine builds. So I'm wondering if this is a bad idea on through bolted engines ... ?

Click to expand...

My head is a Combat so for years have run a 0.030" steel base spacer (for appx. 9.3:1) with smear of silicone. No looseneing, no leaks. Just did the head to fix a front stud leak and the main thru bolts clicked the torque wrench at 30lbs/ft. (750 bored thru bolted barrels from Norvil BTW, when I was still buying from them in 2002/3!)

Concerning the re-torquing problem. Take a look at the fasteners. The old cylinder base nut shown below is flaring out on the bottom. Its deforming and getting shorter.


The cylinder head washer has concentric circles from the bolt head gouging into it. Its getting thinner and changing dimension.


Stainless Steel is not very hard either. Its easy to see why re-torquing is necessary and what happens after repeated re-torquing.

12 point nuts and grade 8 hardware as shown below are superior to the soft, de-formable stock hardware. 12 points are nice because they offer more wrench positions and less tendency to damage the nut.


High end racing can show the weakness of the cylinder to case joint. Extreme RPM ultra short strokes can loosen at the cylinder base and cause rubbing between the cases and the cylinders. Nitro speed record or drag motors can loosen the cylinder base nuts to the point of blowing oil.