Cam wear/valve shim question

[Denny]

Did a search to no avail. But do the shims need to be replaced because the cam itself has been worn out of spec or the valve has been worn.

I'm asking because I'm wondering if it's ok to swap my original cams and shims that were 60Ked last year into another head and they would still be in spec? Or would the valves in the head that the original cams are going into be what causes the need for a valve adjustment?

Thanks in advance

 

[SHOtimer]

Well, you need to replace the shims, which rest ontop of the valve. These need to be replaced because they are a softer metal and wear so that the cam doesn't, therefore creating the gap. The valve itself doesn't wear, it is the shim that is on top of the valve that does. Also, two heads will fit cams and shims differently, so if the cams and shims are all within spec on one head, they will be totally different once moved to another head because the spec inbetween each cam lobe and shim will change when installed in a different head..throwing each out of alightment. So, it would be ok to swap the parts but, it would be much simpler to adjust the valves in the new head. Well, at least that is my understanding
Doug

 

[sdpatt]

Just to add a little to what SHOtimer already said, the shims rest on top of the tappets (upside down buckets) that cover the valve springs. The cams are a hardened metal that are not intended to wear. The shims, on the other hand, are covered with a slightly softer metal that is intended to sacrifice itself to protect the cam lobes.

As the shims wear, the small gap between the cam lobes and the shims will increase. This results in higher rates of wear and possibly cam lobe wear from the greater energy of impact when the lobe strikes the shim. If the shims aer allowed to wear through the softer outer surface, the cam lobe will be damaged along with the shim.

Regarding the transfer of the cams to other heads, every head is different and will require a complete re-measure of the gap to fit new shims. The median gap (.20mm intake, .30mm exhaust) for the engines as they left the Yamaha assembly required shims of around 2.500mm in thickness. While performing the first valve gap adjustment of many engines, I have seen shim sizes ranging from 2.300mm to 2.600mm. So even from the factory the fabrication and assembly of the engines required a wide range of shim sizes.

 

[Underdog]

Denny,

I'm curious as to what you are doing. Are you replacing the motor in that car? It spun the rod bearings, yes? I hope those cams are going into a 3.2 head or at least a 3.0 head on a 3.2 block.

 

[Denny]

Thanks for your input gentlemen!

Ok, here's what I'm trying to do. I've found a relatively affordable, relatively low mileage(67K) 3.0 engine close to home. I was thinking that I'd just drop that into my SHO(3.2 can come later when I have a real job providing that the car lasts or I don't sell it first) But since I'd have to go through a 60K on this motor now, I was thinking maybe I could swap the cams over from my motor that was adjusted. So now that isn't feasible and I'm assuming that a valve lash adjustment would be much easier and cheaper than just swapping heads.

My debt in the last year stayed just about the same, so spending money on the SHO is going to be kinda hard to pass by the parental units and the girlfriend do you think if I fixed up the body I could get $2,000 for my SHO if I did decide to sell it?

 

[AREA 91]

Denny, You have a Y pipe for sale??? How much?

 

[Denny]

witsimpala:
Denny, You have a Y pipe for sale??? How much?

You have PM