They may be multi-layer metal gaskets which are considerably thinner than the composite fiber gaskets. Really though, if you don't have any leaks, I wouldn't worry too much about it.

 

I was having a small leak and i put some fiber ones on and know when i drive and stop I get some some like they a burning. it is becuase they are new.

 

Could be,but it may be where you handled things to get them on there,and grease etc got on the manifolds. let it burn its self off. Just keep a watch out on possible fires etc.

 

I did the work on friday and they are still smoking. I didn't drive it yesterday i just changed the oil and started it up. I went and got gas tday and noticed the smoke.

 

I never run manifold gaskets on gen 1 v8s with stock manifolds. Didn't have to run them on any 60 degree v6 or the 4.3s I've owned. As long as the manifolds aren't warped or cracked they seal off.

Headers are a different story.

 

I will see how it is tomrrow. I might end up takening them off.