According to both Merriam Webster and the Oxford English Dictionary, cambric is pronounced came'-brick. Common usage generally comes to the fore and I suspect cam-bric will be added as an alternate before long. Look at what happened to cov-ert, now generally pronounced co-vert (which makes no sense). At least cambric comes from a Flemish word which begins "Kam-." The academic bent is prevalent in the Oxford Dictionary, and also in the Merriam Webster, but the latter has more alternates from other parts of the British Islands and the USA and Canada. The Oxford, in current editions, is going the same way (perhaps they will no longer call serviette vulgar usage, since most middle class English and many Canadians use the word).