There's gold in that thar oil

Apr 22, 2020
Country flag
Modified Norton P11

Motor was quiet, oil looked clear, running great, but then I struck gold again. Gold like JSM bronze lifter block gold that is. Metalic green oil when drained.

The motor got a little noisy just as I pulled onto the HWY and gave it the beans. (Found out later that the grub screw on the drive side cylinder backed out 1/8th".) Sounded like a valve lash adjustment was way out. Kept running, but I'm sure the lifter block is not looking too good anymore. Hard to say if the soft block could damage the cam, but it probably could. Haven't started it again to see if running the screw back in would reposition (lift) the block up high enough for cam clearance. Probably not though. More than likely it would tighten the lifter block up lowered in the lifter bore.

Will be kicking the motor over to see if there is excessive resistance with the grub screw tightened up in the lifter block to see if it is still a ticking time bomb. Yes, the screw had Loctite on it, and dried for 48 hours before I ever started the motor the first time. I didn't want to be tearing into this motor so soon. Actually, didn't ever want to be tearing into this motor again.

By the way, before the peanut gallery starts telling me "subliminally" that I can't follow directions and should not own tools, the same thing happened to one of the Norton racers Storm42. Check the Post "Racing 2022" page #37 for Storm42's brief details about the grub screw coming loose.

I was not racing, but I was in the push stage of the motor break in. I was not treating the motor with kid gloves anymore. Really wish I'd checked the grub screws again before taking off for the ride. I checked them two rides back and all was good, but I had not started pushing the RPMs yet.

Again, I believe radiused stock tappets would be trouble free on a street ride with a JSM cam in it. Think about it before you lays down your money.

Side note: The Molnar crank with the MAP long rods and short skirt pistons was perfectly balanced at higher RPM. Smooth as a solid mounted Norton twin can be on the HWY and everywhere else. Better than it has ever been. Didn't get over 85mph though, cuz I knew something was off when I heard the ticking near idle RPM just before getting on the HWY entrance ramp.

Oh well, guess I'll be doing more yard work this summer than riding.
That is very disappointing.

Just a bit!
I'll have that worry too now.
I used Loctite but thinking of staking as well.
Edit: Probably not a good idea punching cast iron and a hardened grub screw.
Last edited:
Yeppers a touch disappointing.

I got in one good HWY entrance cloverleaf sweeper turn before getting on US5. That is going to have to hold me over until the garage warms up and I feel like taking it apart. Might start in May and see what's up.

It may not be that bad in there. I did not see any bronze chunks or shavings, just very fine powder like bronze dust. I think the interference issue is not severe and sounds worse than it is as far as damage is concerned.

After tightening up the grub screw and kicking it over plugs out I get a pair of ticks on the drive side. So the grub screw is not moving it back up into position, and it dropped more than I thought it would with the tab in there. There was a few thou of slack on my tab. Don't do that. Make a tab with zero clearance so it holds the lifter block up if the screw decides to back out. Tedious, but apparently could be worth the effort. Those tabs can be made from 1/8" aluminum flat stock available at hardware stores if you don't already have a bunch laying around.

I think it's kind of a rare occurrence for the screws to come loose. Most of the Nortons set up with the JSM lifter solution are probably fine. I just thought I wouldn't have that issue and didn't double check before it got loose.

I'll caulk the whole thing up to a shoulda coulda error. Or maybe just a bunch of bad karma coming back to kick my butt.
that's unfortunate. I hope you'll be able to save these costly parts.

I never liked the grub screw solution to keep the tappet blocks in place. Why not put threads in the lifter block and skip threads in the barrel? Tight bores through the barrel and application of a sealer should prevent oil leaks through bores.
Another idea may be to modify the tappet location plates in such a way as to clamp the tappet blocks in place. I've not looked into the details as yet, but location plates are held by 2 screws each, so they will not rotate. Location plate could be made to include a "finger" entering a corresponding groove in the lifter block, thus preventung up and down movement, and there would be no need for a grub screw anymore. Screws holding the location plates are already wire locked, so nothing will come loose.

Your reactions why this could work (or not) are welcome.

- Knut
It's only money. Building up the desire to dig in and the time it takes to complete the work needed to be done is what bothers me. I know once I get started I'll enjoy parts of it. I always find something that needs a little more personal delusional attention.

I would think this has all been discussed by wiser men or women than I in the past.

I went out and did some head scratching examining my old iron barrels and last set of lifter blocks. Looks like eliminating the screw and relying entirely on the tab to prevent any up and down movement would be difficult without an interference fit of the tab. Doing that would be painfully time consuming. You'll see if you get started with installing the JSM lifter solution. I'm sure Jim tried a few other ideas, but settled on the screw through the barrel base to make the job slightly easier.
The barn yard engineering continues. I tightened up the original grub screw a little more and installed a second grub screw in each hole and locked them down like valve lash adjusters. It is an ugly fix, but I doubt the grub screws up against the lifter blocks can back out.
There's gold in that thar oil

Changed oil and spin-on oil filter, obviously, then squirted some extra oil down the pushrod tunnel associated with the loose grub screw. Started it and it sounds like an old Norton, no tick, tick, ticking at idle like I heard right after the ride when the grub screw came loose, so I'm going to test ride it next time the sun comes out and see what happens.
Last edited: