Cam lobe pitting

[MotoArts]

FINALLY got off my butt and attempted to complete my cylinder head "project" today.

Anybody have any REAL WORLD experience with a pitted cam (on any engine)?
Lobes had what appeared to be VERY minor rust spots. Wiped them with some red Scotchbrite, and the pits are minor but numerous on the ramps and on one nose. Could just barely feel the edges with a fingernail or pointed scratchy tool. Rubbed them crosshatch style with some very fine aluminum oxide sandpaper, and they can barely be felt now.

I wonder where the threshold of usable/trash is with this deal?

 

[bomber315]

eh, i would say it is usable, perfect no, put should be alright... i would probably get another stock cam, since they are cheap (used) tho... it doesnt seem right to put something like that back together when you know its not perfect

 

[DeadLastRacing]

Pitting on the cam? How long did it sit?

 

[MotoArts]

Dunno.
Ebay cam, acutally looked really decent, rust and wear wise.
The rust that was on the lobe appeared new (small light orange spots) and very little at that. But when I scotchbrited it...errrr, damn.
Other lobe is fine.
Yeah, it's just one of those things... I'll probably try hand sanding the lobe, and polishing it with a bench buffer to see how much of the pitting will go away, then keeping it for a spare. Just sucks changing rockers if they get chewed up...

Now my other worry is that I have several used HP cams for my cars on the shelf, and I'm sick to think they have some rust from condensation in an unheated garage. They were oiled, but still... I'm afraid to go & look...

Note to self: grease the shizz out of a cam before storage for any length of time.

The original cam was trash due to what I suspect a PO not knowing how to change oil. The filter was so plugged it was collapsed, and probably starved the top end for lube. The cam bearing and rocker wear pads were burned blue, cam bushing is welded to the cam, and both lobes were toast. Even the rocker shafts had begun to gall up. I'm sure that's what took the tension out of my oil rings and made it a smoker. Surprisingly, the standard bore and piston are in perfect shape.
For my next trick, the oil port on the head will be plumbed for an oil pressure gauge, just to be on the safe side.

Anxious to get it fired up again now...

 

[hawkster0001]

i got two oil pressure gauges, sell them for next to nothing, i just dont know anyhting about em so i dont know how a cable would connect two them

 

[elwood]

For my next trick, the oil port on the head will be plumbed for an oil pressure gauge, just to be on the safe side.

Cool, will you do a write up with pics :tup:

 

[MotoArts]

i got two oil pressure gauges, sell them for next to nothing, i just dont know anyhting about em so i dont know how a cable would connect two them

First need to know if they are mechanical or electric. The electric will require a sender on the engine and only wire to the gauge, mechanical will use just a tube from the engine to the gauge.
If you're not sure, post a pic of the backsides 'em.

 

[hawkster0001]

there mechanical, i have two of different sizes, i will get pics tommorow.

 

[MotoArts]

OK, now here's another thing I wouldn't have seen coming.
How about a defective, yet immaculate appearing, cam?

Turns out to be a non issue though. Got me another new used cam. The inner cam bushing (that rides on the needle bearing) had been installed at the factory over a large gouge and a scratch that ran halfway around the cam journal. Almost looks like the cam was hit with a chisel after heat treating. I can't explain the radial scratch though. The bushing never had a chance to rotate on the cam itself during normal running since there were a few high spots. I used my 4" grinder to cut 2 flats on the bushing and make it like a "nut" (almost down to the cam itself) so a pair of vise grips could crack it without breaking the cam (I tried everything in the tool arsenal beforehand . The good thing is cam and the bushing both showed zero wear on their working surfaces. The cam journal was still black, not "polished" and used looking. The bushing did not have any heat bluing or even any wear on the inside that showed that it ever rotated on the cam.
My guess is Yamaha had to have pressed these together at the factory.
I'm just going to smooth out the high spots and install it with the original bushing that came out of the engine and all will be good.

Who woulda thunk it? I'd be willing to bet that most don't know that bushing is even supposed to move on the cam.

 

[MotoArts]

These are the 2 bad cams.

Cam on the left is the original, with the galled on bushing. On the gear end of this one, even the pin is toasty brown from heat! Note the reduced lobe ramps...that's a wide notch ground in by the rocker arms, leaving a ridge on the edges of both lobes.This was after I dressed the ridges with a dremel, and before I noticed the bushing was welded on...

Right side cam has the pitted lobes. See how nice and clean the journal for the bushing is.

 

[dirtrider73068]

I would replace the cam, wouldn't put it back in if it looks likes its worn pitted or burned I would replace it just to be safe.