Valve train parts…serviceable or not?

[Mikepacific60]

Hi all,
Appreciate views on these two parts…
The first one is the tachometer side cam journal (SL350K1)….the wear marks in the journal shown actually look worse in this close-up photo. The marks are barely detectable using the ‘rub it with your fingernail’ test. I was planning to rub that area lightly with #1000 sand paper, just sufficient to remove any possible high spots (not trying to polish out the marks altogether):


The second photo below is the left cylinder end of the cam…again, the marks look worse in the photo. I was not intending to do anything about this - just use it as it is:


I do have spare parts from a later SL350 engine which look to be in better condition, but I’d prefer to use the original parts as the cams have different numbers…probably just different production runs, and I’m not too sure about swapping the cams in terms of the very thin thrust washers. The other cam journal piece, while good inside, looks lousy on the outside.
I’d welcome opinions,
Cheers
Mike

 

[ancientdad]

I'd replace both if you plan to actually ride the bike a fair amount. The pitting in the cam lobe is going to continue to get worse over time, and we don't know how much worse in how much time and at some point it will start to cause wear on the rocker arm. The score marks in the cam bearing give the impression that the engine was briefly oil-starved for some reason. Clearance is the key with cam bearings, they survive on a thin film of oil and if the clearance is excessive there will be oil loss as well as slop that will affect the valve timing (if it was on the other end it would be worse, it would affect the points and timing). If the other cam is from a K2 it should be the same, part numbers show the same for K1 and K2. The thin shims are only used as needed and not cam-specific, the end play between the cam bearings varies from engine to engine.

 

[MrPepper]

Ancientdads recommendation is good.

I would not hesitate to install and run both those parts, and have assembled engines with similar condition parts. I've actually been meaning to track down a pitted cam like that and build an engine to see what long term rocker wear is.

I should also note that I build and use things with the primary goal of using them, knowing that they aren't perfect parts going in and may need attention (rebuild with replacement parts) later. Someday, I would like to do a build like ancientdad with top shelf parts and have a nice solid bike, but I'm not there yet.

Check if Tach side wear is within serviceable limit. If so then use it... sand as little as possible and measure after. With oil issues, the tach side is the last to get damaged, so it should be abundant and easy to replace.

 

[Ribrickulous]

The cam bearing would worry me.

I’ve read about the pitting in cam lobes being due to casting defects near the surface that stabilize over time, but I just had mine hard welded, so don’t take this as personal experience.

The cam bearing is just that, a bearing.

If you felt any rough spots in a roller or ball bearing, you’d scrap it immediately


-Ed
1972 CL350