Lost compression on cylinder 3

[BammBamm]

I recently installed an 1800 head on my 2.0 1982 go spider. It has been working great with lots of power. Today all the sudden it started to dog. When I removed cylinder 3 spark plug wire or injector cnnector it made no difference to how it idled. I think my compression gauge is off but tells me what I need to know. Other cylinder are at 100-125 psi but cylinder 3 us at 25psi. When I pulled the valve covers I see heavy wear to the exhaust cylinder 3 cam lobe. It wasn't like that 6 weeks ago. The gap is correct at .45mm. Do I have a stuck valve? What caused the wear?

[So Cal Mark]

lack of zinc in the oil

[BammBamm]

Could you please elaborate about the zinc in the oil? Only the cylinder 3 exhaust love is damaged. The rest look fine and its that cylinder I lost compression. I have been using the same oil for the lasts year with no visible wear for the last year. Only when I installed the 1800 head

[seabeelt]

Bill, Lack of zink causes wear in older engines. I think most folks are using Rotella T for Diesel or something similar. Lack of compression symptom is different than the valve not opening all the way. Could be a valve is stuck partially open, or could be a blown head gasket, or could be a ring problem in that cylinder. Probably the first or the second rather than the rings. either way looks like you will need to pull the head

[MikeHynes]

When you installed the 1800 head did you mix and match used shims with a used cam?

[BammBamm]

I had to buy all new shims to match asset of 1979 2000 cams. What valve spring removal tool should I buy?