How do I adjust the timing chains on my triplet?

How do I loosen and rotate the eccentric within the bottom bracket?

I have FSA Gossamer cranks and Mega Expo BB.

Thanks,
AA6

Given you have a triplet, you would normally adjust the chain tension between the middle stoker position and the rear position first, and then adjust the chain tension between the middle stoker position and the captain's cranks. Your tandem's builder is usually attentive to the boom tube lengths and you should not need to use a half link on either of the sync chains to get the eccentric into a neutral position.

As for the actual adjustment process, here's a link to the instructions for the Bushnell eccentric's used on your triplet:
https://www.rodcycle.com/articles/eccinstructions.pdf

Here's a link to the Bushnell eccentric info page in case you'd like to learn more about that wonderful design and it's evolution: https://www.rodcycle.com/eccentric.html

The only thing missing from the history is the credit due Todd Shusterman for many of the refinements you'll find in the current / '07 version of the eccentric.

Thanks Tandem Geek. Exactly what I needed.

I wasn't unscrewing the adjustment bolt enough in the eccentric to loosen both wedges.

The forward chain is still too loose even with the BB in the most forward position. I'll probably have to take off a link.

I wasn't unscrewing the adjustment bolt enough in the eccentric to loosen both wedges.

A very common finding for first-time users of the Bushnell. It certainly "feels" like it should be loose when, in fact, only one of the two wedges has been pulled all the way back.

The forward chain is still too loose even with the BB in the most forward position. I'll probably have to take off a link.

If it's all the way forward then yes, a full link should allow the eccentric to rotate the BB towards the back of the eccentric. In some cases a 1/2 link may be required to get your BB into a more neutral position in the eccentric or to otherwise work a saddle set-back issue. In fact, I have a 1/2 link on our Erickson's sync chain.

Check the position of the other BB... try to "distrubute" the chain slack amongst the BB's...