Drilling a rocker shaft

The bit is 3/32 or 2.5mm
If you drill both inlet rocker shafts you can eliminate the hose that goes across the top of the head. Then you can plug the other hole or use it for a handy place to connect an oil pressure gauge. Jim

[video]https://www.youtube.com/watch?v=4X_ntXpN7As[/video]

I had to go back and listen to the carbide bit when it first makes contact at 1:15 in the video. It makes me laugh/cringe, knowing that if it had been me running the lathe, I'd have been picking chunks of carbide out of my face when it made those kinds of sounds.
After watching poor SwooshDave's thread about the not-funny-oil-t24460.html, I think an oil pressure gauge would be a great addition for the unused head port as you suggested.

Nathan

Nater_Potater said:

I had to go back and listen to the carbide bit when it first makes contact at 1:15 in the video. It makes me laugh/cringe, knowing that if it had been me running the lathe, I'd have been picking chunks of carbide out of my face when it made those kinds of sounds.
After watching poor SwooshDave's thread about the not-funny-oil-t24460.html, I think an oil pressure gauge would be a great addition for the unused head port as you suggested.

Nathan

Click to expand...

Yeah, face shields are generally a good idea with carbide...if you value your creamy complexion.

When I did mine I used a small ball end carbide bit with the lathe making scary turbine like noises as it got upto speed, then used compressed air to keep it cool while cutting. The hardening on mine is quite deep, over 1mm.

Cheesy said:

When I did mine I used a small ball end carbide bit with the lathe making scary turbine like noises as it got upto speed, then used compressed air to keep it cool while cutting. The hardening on mine is quite deep, over 1mm.

Click to expand...

Yeah, many years ago I used to use a drill press with a ball nosed carbide burr mounted in the vise and the shaft mounted in the spindle. It works fine- just not as fast as an end mill in the lathe. Jim

When I say bit I think it was a 1.5mm ball end slot drill (or imperial of similar size), this was supervised - maybe dictated by the toolmaker... The ball end was so it dont chip the corners off, the compressed air was to keep it cool without the risk of thermal shock (from a liquid coolant)

Jim you say to do both inlet Vv shafts, is there any need to do the exhaust Vv shafts as well?
Regards Mike

Brooking 850 said:

Jim you say to do both inlet Vv shafts, is there any need to do the exhaust Vv shafts as well?
Regards Mike

Click to expand...

No need to drill the exhausts.
The exhaust rocker shafts do not meet in the center, only the intakes, which will provide a path from one side of the head to the other. Jim

So who will do this for me and at what price? I've thought about this several times. It would be nice to get rid of that hose above the head.

DogT said:

So who will do this for me and at what price? I've thought about this several times. It would be nice to get rid of that hose above the head.

Click to expand...

If you want to send them I will do them. How about $25.00. Jim

If you want to send them I will do them. How about $25.00. Jim

Click to expand...

It would have been worth that and the shipping to get mine done considering what I spent on a carbide centre bit and regular carbide twist bits. The centre bit did one shaft up to the bit's effective length but the regular bits would not touch the surface. In the end I had to admit defeat. Nice to see it done anyway.

I'll PM you Jim when I get them out. I'm not in a big rush, this is the best riding weather right now. Thanks. Or I may just buy a spare set if they're not too dear.

Keith1069 said:

If you want to send them I will do them. How about $25.00. Jim

Click to expand...

It would have been worth that and the shipping to get mine done considering what I spent on a carbide centre bit and regular carbide twist bits. The centre bit did one shaft up to the bit's effective length but the regular bits would not touch the surface. In the end I had to admit defeat. Nice to see it done anyway.

Click to expand...

Keith, it might work out cheaper to just ask Jim to supply a new pair of spindles, pre drilled by him, and shipped to you... That's what I've done!

Why?? Does not the existing system work well enough? In all my MANYyears I have never experienced or heard of a rocker seized on its shaft. Of course it helps if there is still oil reaching the motor.....In early days were not the rockers fed from a restrictor in the oil retun side of the pump and only later was it taken from the pressure side of the pump? In really early days rockers were grease lubricated every once in a while and that worked well enough ASSUMING someone shoved a shot of grease into the nipples every once in a while..... If I remember the investigations carried out at Norton many decades ago by John Hudson, the then Service Manager, measureing oil pressures will only lead to owners worrying and buying new oil pumps on a regular basis!
And while on the subject....not long ago whilst trying and as usual failing to wind up a friend and hearing what he was doing that day I asked .... 'How many poxy oil pumps are you manufacturing for Nortons per year ??...... 'Yee gods most Norton owners dont ever do enough miles in half a dozen life times to wear them out...do they not know how to service a gear oil pump?' He replied something to the effect that the great majority of owners clearly do not realise that ALL gear pumps leak oil past the gears and if they dont then the gears will not turn in the oil pump body so they assume the pump is knackered and buy a new one and in so doing keep him employed for a day or se every so often shoving together and tesating new ones!
Of course he does offer a service to his customers to modify the timing cover to include the anti drain system of the Mk 3...a system which IF it fails can only fail SAFE allowing oil past it....
But these owners replacing their oil pumps do keep people employed in the UK which is jolly good of them and I get a warm glow as I phone my friend thinking to myself that somewhere in the UK there is still someone producing bits for sale around the World even if in the great majority of cases they are not needed.....

OOPS I forgot that anyone with an unmodified Combat could well of had broken piston rings flow back through the pump.....which does the pump little good and could require a new one.... Bloody clever idea by a total brain dead were those Combat cases...Mind you they were only £20 a set in a Birmingham warehouse shortly after NVT went arse over tit and were easily convertable back to the earlier good old piston ring stopping filter system along with installing a proper breather that does NOt return more oil back to the tank than the oil pump ever did!(A std joke amoung knowing Norton owners!!) Does anyone know the name of the person responsible for those Combat cases?

J. M. Leadbeater said:

Why?? Does not the existing system work well enough? In all my MANYyears I have never experienced or heard of a rocker seized on its shaft.

Click to expand...

Nothing to do with rockers seizing.

As Jim already said :roll: :

If you drill both inlet rocker shafts you can eliminate the hose that goes across the top of the head.

Click to expand...

I can kind of see where JLM is coming from. Like, "what wrong with the old stuff" and " if it ain't broke, why fix it". It's neither a sin to think forward nor to keep old school in your heart.

Sure, he rattles on and sometime only light grazes the topic. But Troll? I don't think so. He's just old school. Not a sinner.

There may be some scary aspects to this mod like what do I use to block the left side of the head or maybe what if the left exhaust rocker gets a bit starved for oil. Maybe these fears are unrealistic, but they could certainly come to mind. That crossover pipe is pretty much obscured anyhow. As far as a pressure gauge goes, it is just a matter of the double banjo and another copper washer.

Anyhow, new ideas are cool to me and the next time I pull my spindles I may drill them....or maybe not.

Jim, if you get a bit backed up, feel free to PM me. I'll take some of that gravy. At 5 to 10 pairs an hour, that retirement sure comes into view. Believe you me, I have the equipment, tooling, and the skills for this one.

I hope I'm not out of line here, or am I over stepping my guest privileges.

pete.v said:

I can kind of see where JLM is coming from. Like, "what wrong with the old stuff" and " if it ain't broke, why fix it". It's neither a sin to think forward nor to keep old school in your heart.

Sure, he rattles on and sometime only light grazes the topic. But Troll? I don't think so. He's just old school. Not a sinner.

There may be some scary aspects to this mod like what do I use to block the left side of the head or maybe what if the left exhaust rocker gets a bit starved for oil. Maybe these fears are unrealistic, but they could certainly come to mind. That crossover pipe is pretty much obscured anyhow. As far as a pressure gauge goes, it is just a matter of the double banjo and another copper washer.

Anyhow, new ideas are cool to me and the next time I pull my spindles I may drill them....or maybe not.

Jim, if you get a bit backed up, feel free to PM me. I'll take some of that gravy. At 5 to 10 pairs an hour, that retirement sure comes into view. Believe you me, I have the equipment, tooling, and the skills for this one.

I hope I'm not out of line here, or am I over stepping my guest privileges.

Click to expand...

Hey, no problem if you want to drill some shafts. The video was intended to be DIY instruction anyway. Keep in mind your going to have to buy a new bit and a carbide after every few... Jim

Fast Eddie said:

.........Keith, it might work out cheaper to just ask Jim to supply a new pair of spindles, pre drilled by him, and shipped to you... That's what I've done!

Click to expand...

I was thinking along the same lines, Nigel. I'll have to PM Jim, this is something that I have wanted to add to my bike ever since I heard about it. Cj

@ CJ, email Jim, I did and he's happy to oblige.

@ Pete, not sure why you seem so agitated by this thread my friend. If you don't feel the need to modify your rocker spindles then the solution is easy... Don't! For those who do, for whatever reason, this is an interesting thread.

Personally, I still intend to fit an oil cooler, this mod tidies up the under tank plumbing which will help when I do so. It is also good engineering practice though. Generally, engine designers build their oil galleries internally, this simply doing the same. It most certainly has nothing to do with increasing oil flow or preventing rockers from seizing as Mr Lb incorrectly assumed, and then proceeded to labour the point of.

Keith, it might work out cheaper to just ask Jim to supply a new pair of spindles, pre drilled by him, and shipped to you... That's what I've done!

Click to expand...

Now that would have been sensible but I have the 'Special ' Les Harris ones with BSF threads :lol: Don't want to spoil 'Originality'. :|