Engine torn down where do I go from here?

Happy New year everyone,

I finally got around to the final piece of my rebuild, the motor. I tore it down this weekend and which I still have to check the tolerances the engine seemed to be running ok.

Pros -
Tight rod end bearings no ovalization with fair side play.
Main bearings were all tight and lubed properly
no metal shavings or sheen in the oil

Cons -
Both pistons had broken rings and left side piston had some wear on the exhaust port side.

So the question... I've read tons so far of tricks, gimmicks and mods to do to the engine and my question is to the norton vets here. What, if any mods, for reliability can be and should be done and what parts should be replaced now while the engine is apart even if they're within spec? This will be a long term runner not a racer so I'm looking for reliability. I read that because rods aren't too expensive that those should be replaced along with pistons. I was very interested in the CNW breather mod, if it means that I'll reduce the chances of seeping and also reduce internal pressure. What have you done without regrets?

Anything you guys can provide would be great! I'll post pics of the engine shortly.

Mario

At a MINIMUM-

All bearings & bushings

Valve job (check valve stems & guides, replace if even CLOSE to end of spec)

Pull open the crank, clean it out. At least static balance with rods, bearing shells, pistons and rings' weight matched/balanced.

Next oversize only if the cleaned up honed bores result in more than .0045 over the new piston diameter.

383wss said:

Cons -
Both pistons had broken rings and left side piston had some wear on the exhaust port side.
Mario

Click to expand...

Did you recover all the pieces. If not, you need to explore the oil ways/tunnels. You can sometimes see pieces in the holes behind the oil pump.
That being said, and even if you retrieved all the ring pieces, you should inspect the tunnel anyhow. You will sleep better knowing they are clear. I cannot help thinking that many fresh rebuilds have failed due to this missed step. My current set of cases showed evidence of catastrophic failure. I found 1/4 to 1/2 a teaspoon of shrapnel in the tunnels. There are 3 or 4 grub screws, (some have less, some have more) to remove that allows for flushing and inspection. You will see them if you look for them in the logical places.

All in all, Taking everything apart to inspect is good thing to do and does not mean you need to replace everything just because you are in there but you most certainly can if you feel. Some things like crank bearings, if found to be sound may be better left untouched, literally, unless you are going racing, which you are not. As you can see, by the first few post, it doesn't take long to get confliction advice. Usually, you already know what you will or will not be doing and these post are part of the process. It's what we live for

I have 3 years on a rebuild and have just pulled the top end to inspect the JS1 cam, BSA lifters and related items. Piston and cylinders, rings bedded in, valve sealing great. Again, no need to replace any of this stuff just because I am in there. All is perfect so I will re assemble knowing where I stand and get in some head mounting practice. You'll see what I mean when you get there.

grandpaul said:

At a MINIMUM-

All bearings & bushings

Valve job (check valve stems & guides, replace if even CLOSE to end of spec)

Pull open the crank, clean it out. At least static balance with rods, bearing shells, pistons and rings' weight matched/balanced.

Next oversize only if the cleaned up honed bores result in more than .0045 over the new piston diameter.

Click to expand...

Absolutely great answer and what responses I'm looking for. Thank you!

pete.v said:

383wss said:

Cons -
Both pistons had broken rings and left side piston had some wear on the exhaust port side.
Mario

Click to expand...

Did you recover all the pieces. If not, you need to explore the oil ways/tunnels. You can sometimes see pieces in the holes behind the oil pump.
That being said, and even if you retrieved all the ring pieces, you should inspect the tunnel anyhow. You will sleep better knowing they are clear. I cannot help thinking that many fresh rebuilds have failed due to this missed step. My current set of cases showed evidence of catastrophic failure. I found 1/4 to 1/2 a teaspoon of shrapnel in the tunnels. There are 3 or 4 grub screws, (some have less, some have more) to remove that allows for flushing and inspection. You will see them if you look for them in the logical places.

All in all, Taking everything apart to inspect is good thing to do and does not mean you need to replace everything just because you are in there but you most certainly can if you feel. Some things like crank bearings, if found to be sound may be better left untouched, literally, unless you are going racing, which you are not. As you can see, be the first few post, it doesn't take long to get confliction advice. Usually, you already know what you will or will not be doing.

I have 3 years on a rebuild and have just pulled the top end to inspect the JS1 cam, BSA lifters and related items. Piston and cylinders, rings bedded in, valve sealing great. Again, no need to replace any of this stuff just because I am in there. All is perfect so I will re assemble knowing where I stand and get in some head mounting practice. You'll see what I mean when you get there.

Click to expand...

Thank you! good to know. I don't know how many miles are on it but I've torn down other engines before and this one was by far the least worn from what I can tell. Then again it is my first Norton rebuild. As for the rings. they were cracked and still seated they literally just came off when I pulled the sleeve off. I'll still check and clean for any missing shrapnel but I didn't see any.

There shouldn't be a need to change the rods if planning road use only but the big end bolts should be changed because they stretch when torqued. You can measure them to see if ok but I wouldn't take any chances.

What I have done without regrets?

- Replacing standard rods and pistons with Jim Schmidt's longer Carillo rods and forged pistons ( + his camshaft, BSA-like lifters and pushrods)
- Installing Jim Comstock's reed valve breather (really straightforward on a 1972 engine; no more worries about wet-sump, no leaks ...)

Laurent

383wss said:

. I read that because rods aren't too expensive that those should be replaced along with pistons.

Click to expand...

Commando rods if in good condition with no outward signed of wear or damage are very strong and if assembled correctly with new good quality fastenings should give no problems for a road engine. In fact many have been used in race engines, Triumph rods on the other hand are know to break with the obvious disastrous consequences. A friend of mine point blank refuses to use old Triumph rods regardless of condition or own history. Mick Hemmings on the other hand says Norton rods give no problems if in good condition of a road engine.

toppy said:

383wss said:

. I read that because rods aren't too expensive that those should be replaced along with pistons.

Click to expand...

Commando rods if in good condition with no outward signed of wear or damage are very strong and if assembled correctly with new good quality fastenings should give no problems for a road engine. In fact many have been used in race engines, Triumph rods on the other hand are know to break with the obvious disastrous consequences. A friend of mine point blank refuses to use old Triumph rods regardless of condition or own history. Mick Hemmings on the other hand says Norton rods give no problems if in good condition of a road engine.

Click to expand...

Thanks! $ saved... I'll still check them thoroughly.

SPLIT the CRANK .

fit a Filter .

What model / year is / was it ??

Whats its use going to be ? .

383wss said:

toppy said:

383wss said:

. I read that because rods aren't too expensive that those should be replaced along with pistons.

Click to expand...

Commando rods if in good condition with no outward signed of wear or damage are very strong and if assembled correctly with new good quality fastenings should give no problems for a road engine. In fact many have been used in race engines, Triumph rods on the other hand are know to break with the obvious disastrous consequences. A friend of mine point blank refuses to use old Triumph rods regardless of condition or own history. Mick Hemmings on the other hand says Norton rods give no problems if in good condition of a road engine.

Click to expand...

Thanks! $ saved... I'll still check them thoroughly.

Click to expand...

Whenever I do a complete engine rebuild on a bike with no history I replace the rods, it is an absolute certainty that alloy rods will sooner or later fail, ok that might take 60 years but do you want to take the risk of destroying an engine
that you will have spent a lot of money on . Save up for some rods and worry about something else.
sam

"it is an absolute certainty that alloy rods will sooner or later fail"

Please tell more about this... :idea:

An ex BSA stress engineer told me many years ago. Alloy has a shelf life of so many cycles before it will/not might
fail. This may take a very long time , but sooner or later.....
sam

The rods are pretty good, but replace the bolts and nuts that hold them together, if you pulling the botton end down replace all bearing, seals, clean the crank out, new timing chain, you don't want to go back down there for a long time, even if the old main bearing are still good still replace them, no need for Carllo rods if your not racing it you can spend the money on other improvements, maybe get the crank balanced to run smoother, what the heck, bigger cam, bit of port work, maybe new carbies, just make it breath a bit better and still keep it relieable.

Ashley

concours said:

"it is an absolute certainty that alloy rods will sooner or later fail"

Please tell more about this... :idea:

Click to expand...

As Trident Sam said, anything made from alloy will eventually fail if subjected to repeated stress cycles. This includes anything made from aluminium, magnesium or titanium. Items made from steel on the other hand can be designed to have an infinite life.

Wish I knew about that aluminium issue before I racked up 8000hrs in her Majesties helicopters. Phew thank God I'm retired.

gripper said:

Wish I knew about that aluminium issue before I racked up 8000hrs in her Majesties helicopters. Phew thank God I'm retired.

Click to expand...

Oh, so helicopters never suffer from metal fatigue then ?
Don't you just love a smart arse.
I was relaying information that I was told from a much better educated man than me, I don't care if you believe it or not.
sam

gripper said:

Wish I knew about that aluminium issue before I racked up 8000hrs in her Majesties helicopters. Phew thank God I'm retired.

Click to expand...

You've misunderstood what was said - aluminium WILL fail given enough stress cycles, albeit that it may be a very high number. This will vary according to various factors, such as component design, material make-up and usage. Your helicopters are very carefully monitored - you must be aware of the need to change certain parts at a given number of hours. That's why.

Dr Paddy_SP, Phd (Materials Engineering)

What a bunch o crap. Absolutely, positively, EVERYTHING will fail eventually.

383wss, maybe you better just get rid of that damn before someone gets hurt. :roll:

grandpaul said:

At a MINIMUM-

All bearings & bushings

Valve job (check valve stems & guides, replace if even CLOSE to end of spec)

Pull open the crank, clean it out. At least static balance with rods, bearing shells, pistons and rings' weight matched/balanced.

Next oversize only if the cleaned up honed bores result in more than .0045 over the new piston diameter.

Click to expand...

I am sure, as an example, 383wws and others would like to know where you are at with the motor on your JPN "restoration". What rods, pistons, bearing, valves, valve springs, etc, will you be using? Will you be doing your own bore job? Do you have a particular balance factor in mind for yours? :? :?: