So the truth is I actually have no idea what belt Monty was running before it jumped off at Castle Combe, once it had left the party there was no walking the busy track to go looking for it!
Monty's original belt easily could have been a lot longer than the PK61305 I fitted on Thursday, actually of all the belt sizes quoted the 1,305mm option remains the shortest we now definitely know will fit. Once I'd confirmed the correct run, fitting the PK61305 was straightforward enough, if you're planning on carrying a spare belt don't forget to also pack a ratchet & 17mm socket, or a 17mm ring spanner to compress the tensioner pulley spring. With the tensioner spring compressed we got the new belt on ribbed pulleys first, then slipped it's back face over the smooth water pump pulley, it went on fine but I wouldn’t want a belt any shorter than 1,305mm.
The tensioner spring isn't the strongest I've ever felt, but in the case of my 1,305mm long belt I was pleased to find I needed to go right to the stop to get it on, with the tensioner released the belt was left nice a taut just as I would expect. Given Monty spat his original belt and I have my suspicions that one was longer, I suspect it was a lot less taught than what I've ended up with having fitted the PK61305, so hopefully that means I will not suffer the same issue again?
It was pure luck, but I'm left pleased I went with what I'd say is the shortest practical option that fits, especially given that Monty has now proven he can safely rev to 8,400rpm, where I've set the hard rev limiter. I appreciate it's unlikely other's with a Duratec Plus 4 will be revving their engine that high, however, it may be worth checking your current belt tension.
If your current belt does feel a bit lose, fitting a shorter version like the PK61305 I went with may be a sensible idea
Dave.
