Cam Wear

[haydenm315]

I woke up today around 9am and decided that it was a good day to rip my engine down and inspect everything because it still seems a bit loud up top. I found that a lot of the clearances grew since the last time which was maybe 5k miles. The tips of the cam lobes are all smooth and shiny like they're supposed to be, however I noticed that the bottom of the cam lobes seem not as smooth when I run my finger across them. There aren't pits or anything but it seems to be not as polished. My thought is that the cam wore down on the bottom causing the clearance to increase on most of the valves. I've never ran the car low on oil, and I was using amsoil 10w30 before switching to castrol gtx 10w30 2,000 miles ago. Anybody else have shoshop cams? It doesn't make much sense to me. If a cam was to wear, I'd think it would get flat on the tips of the lobes or start to pit as well. I dont' have any of that. Maybe the extra lift from the cams is tweaking my valves and they just haven't fully adjusted themselves?

 

[Markus]

haydenm315:
I woke up today around 9am and decided that it was a good day to rip my engine down and inspect everything because it still seems a bit loud up top. I found that a lot of the clearances grew since the last time which was maybe 5k miles. The tips of the cam lobes are all smooth and shiny like they're supposed to be, however I noticed that the bottom of the cam lobes seem not as smooth when I run my finger across them. There aren't pits or anything but it seems to be not as polished. My thought is that the cam wore down on the bottom causing the clearance to increase on most of the valves. I've never ran the car low on oil, and I was using amsoil 10w30 before switching to castrol gtx 10w30 2,000 miles ago. Anybody else have shoshop cams? It doesn't make much sense to me. If a cam was to wear, I'd think it would get flat on the tips of the lobes or start to pit as well. I dont' have any of that. Maybe the extra lift from the cams is tweaking my valves and they just haven't fully adjusted themselves?

Any wearing of the cam lobes will not increase the gap - the gap is adjusted using the non-lobe part of the cam.

I find it very strange that the gaps have increased after only 5000 miles. Something is not right.

Do the shims show any sign of wear?

 

[yamahaSHO]

Markus:
Any wearing of the cam lobes will not increase the gap - the gap is adjusted using the non-lobe part of the cam.

While this is true, if the shims did wear, then the gap could increase.

 

[shojuan]

haydenm315:
The tips of the cam lobes are all smooth and shiny like they're supposed to be, however I noticed that the bottom of the cam lobes seem not as smooth when I run my finger across them. There aren't pits or anything but it seems to be not as polished.

The rougher texture on the cam lobe heel doesn't surprise me because that's where most of the material is taken off during the regrinds. Probably was like that when you installed the cams. As was asked, any noticible wear on the valve shims? Maybe there was some oil starvation from plugged up oil holes to the cams. The Auto-RX treatment you did will help there. Just redo the shimming, try to get the clearances biased a little more towards the tight range of the specified allowance and make sure to write down the shim sizes that are in there and the shims that you replace them with. I really like Scott's sheet that he published (in the guidelog link at the bottom in my signature) and that he hands out freely if you ask him to email it to you.

After you reshim, bolt that puppy up and don't worry about it for the next 5-10K miles and then take it apart again to see how much things changed.

Edit: Oh, and I forgot to ask! How much cleaner is your valve train area now that you've done the Auto-RX treatment compared to how it was when you installed the stage 2 cams 5k miles ago?

<small>[ May 02, 2003, 06:47 PM: Message edited by: shojuan ]</small>