Norton factory upgrade for cam followers

https://www.accessnorton.com/search/2540887/?q=BSA+radiused+lifters&o=relevance&c[node]=14

https://www.accessnorton.com/NortonCommando/heavy-lifters-and-valve-bounce-2015.18975/#post-283125

jseng1 said:

Back in the 1970s the Norton factory began upgrading their high RPM short stroke flat track motors to BSA type radiused lifters.

They did this because there was valve float problems with the heavy stock lifters and the extreme pounding between the stellite pad and the cam was beating up both the cam and the followers. They used a Sifton 460 cam that was designed for the BSA lifters. The lifter weight was cut in 1/2, the RPM increased, valve float and wear was reduced. Pounding and stress on the stellite pad was reduced.

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CanukNortonNut said:

JS,
Very good with excellent points. What is the average mileage numbers for those who have the BSA lifters installed for street bike running? Racing is great and puts hard facts to the conditions as stated above. Engine strip down is frequent in this environment. Not so for Joe average re-builder who just wants reliable no nonsense engine mileage.
So you sold some of these kits. To know how they do on the open road would be helpful and I am not talking of just your experience on your Atlas, Jim but others who have installed your product who ride. My guess is most don't do mileage... but I could be wrong. It would be informative if there is repeatable and consistent results with plus 30k on the odometer.
Cheers,
Thomas

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Thomas
Laurent noticed this thread so this morning he sent some photos of his hardwelded radius cam and BSA lifters after 40,000 kms of "tourist" speed and rpms. Laurent said he's "not expert on publishing pictures" so he suggested I do it.

This was after a "severe lubrication problem I had after about 30 000 kilometers of use" which nearly ruined the pistons.

Very Good Jim,
That is a start with some mileage with BSA type Lifter and cam. Hopeful more will pipe up.
"This was after a "severe lubrication problem I had after about 30 000 kilometers of use" which nearly ruined the pistons."
So If I am reading the comments correctly then Laurent opened up the engine for a look see and piston inspection/change out at 30000 km (18600 miles) from original install and continued using it as we speak with +40 k and counting? Or is this pix at 40 km (25000 miles)? What is the other cylinder lobes looking like? The same?
Cheers,
Thomas

The wear is about the same on all the lobes and lifters. I posted the photos that showed the best detail. Laurent said he had a problem with an anti sump valve and low pressure which starved the oil and resulted in seizure at 30,000km. The crank journal was badly damaged but the cam survived. He wasn't ready to buy new pistons at that time so he reinstalled them. Now at 40,000km he is replacing the pistons with graphite coated skirts and has provided the 40,000km photos above.

imagine that!!!

jseng1 said:

Laurent said he had a problem with an anti sump valve and low pressure which starved the oil and resulted in seizure at 30,000km. The crank journal was badly damaged

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If you are welding cam lobes, and making followers, it might be worth talking to a metallurgist about materials and hardness and potential cracking. I think the hard surface on R type Triumph followers are brazed onto a softer, but stronger base. I once used soft followers which were hard faced by welding with Cobalite, then re-shaped by grinding. I would not do that these days.

Why are you using BSA followers and not Triumph R-type, which probably have a bigger radius ?

Because the BSA type has a larger diameter shaft, and is therefore stronger.

Also, IIRC, the BSA follower is the same as a Triumph R type at 1-1/8” radius.

Hi All,

Many thanks for posting the pics on my behalf Jim, and for giving my exact comments.

When I saw the damages on the crank journals at 30 000 km, I felt lucky to see that the camshaft and lifters were still in a close-to-new condition.

Some more details on my context:
- Jim's medium CR pistons
- JS0 camshaft
- Standard valve train
- Either Penrite or Motul 7100 100% synthetic oil

L.

Hi Laurent which Penrite did you use , was it the one available from ALP diffusion ?

bill said:

imagine that!!!

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I sense a little Sarc in those two words. Yea. Haven't we heard that song before. Its like the anti sump valves just keep on given....it to us, just like the Energizer bunny it keeps going and going and then kaboom.
If it were not for the JS con rods then the standard rods would have probably Grenade d the case barrels and what ever else got in the way. I've seen it happen and heard about it all too often.
Cheers,
Thomas

laurentdom said:

Hi All,

Many thanks for posting the pics on my behalf Jim, and for giving my exact comments.

When I saw the damages on the crank journals at 30 000 km, I felt lucky to see that the camshaft and lifters were still in a close-to-new condition.

Some more details on my context:
- Jim's medium CR pistons
- JS0 camshaft
- Standard valve train
- Either Penrite or Motul 7100 100% synthetic oil

L.

Click to expand...

Thanks Laurent,
Keep us informed on your mileage. I hope others will pipe up on their BSA type lifter and cam design.
Cheers,
Thomas

Salut Pierre, Thomas and All,

I used the Premium 10 / Full synthetic 10-70 / Full zinc Penrite oil that I got from huiles-de-france.fr/index.php?option=com_virtuemart&Itemid=57.
But it's no longer at their catalog, neither at ALP's one.

Re: the comments about the anti-sump valve, I didn't forget to open it.
But it was designed for and installed on my previous 600 cc / 3-start oil pump engine.
When I switched to a Commando engine / 6 start oil pump, I did'nt verify that the anti-sump valve oil-flow was adequate. I checked it after the problem, and discovered it was about 50 % less than the engine oil feed pipe.
2nd potential reason for the problem: bad setting of the oil pressure release valve which was opening at very low revs and oil pressure.

You're right Thomas: Not sure at all that standard rods would have survived the oil starvation!

Hope that helps.

L.

Although it obviously wouldn’t have felt this way at the time Laurent, it sounds like you were actually quite lucky!

Your choice of good components and good oil clearly saved the day IMHO.