Another cam change question

[steve-v8s]

There is a school of thought that when changing the cam it is beneficial to change the valve springs. The thinking is that they are a tad too strong and the cam suppliers won’t honour warranty claims unless the springs are replaced.

Any truth in this ?

Also, does skimming the heads increase the compression ratio ? I can see it may make the overall volume slightly less. Is it the ratio of swept and unswept volume ?

[mongoose]

When the chaps at v8d put in my h404 they wanted to change the valve springs to suit,just for the reason you have stated.The cam that came out was the original tvr435 cam and the engine had only done 7k miles,one lobe(fifth from front) was already knackered.If you skim the head then you will raise the compression ratio,assuming you use the same head gaskets when refitting the heads,however you can simply replace the composite gaskets with some tin ones,which will raise compression if you dont need to skim the heads,thus saving the life of your heads.There are a few thicknesses of gaskets i believe,you would need to talk to the experts to see which one will give the compression ratio your looking for.When i was at v8d they had a tin gasket there which would change my compression ratio from the std 10:1 to 11:1.
Incidently,its worth knowing that you can change the valve springs without removing the heads(old indian rope trick method!),hope i'm not teaching you to suck eggs here?

[v8 racing]

I certainly would not warrant a cam that does not have the correct springs fitted, like mongoose says no need to take the heads off, out of interest if you are looking to raise your cr if you can get away with a tin gasket you are better using one for performance reasons and they seal just as good as a composite providing your not running silly cr levels