I recently tried changing the eigrp hold-time on a router, but didn't have much luck.
I did: ip hold-time eigrp 23 60 on interface Tunnel0 (that's where the hello's are coming in), but the hold time is staying at 15. I bounced the neighbor and even rebooted the router, and it's still 15...
IP-EIGRP neighbors for process 23
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
0 10.10.255.254 Tu0 12 00:03:53 99 5000 0 116641
My suggestion is to look at the neighbor on the other end of the tunnel and see what it reports the hold time to be. The hold time is sent in the hello packet to the neighbor. What you are seeing when you do show ip eigrp neighbor is the hold time that the neighbor sent to you. If you look in the other neighbor you should see the effect of your change in what you sent to it. Note that unlike OSPF EIGRP will allow hold times to be different between neighbors.