i have just got a set of 3 sums for my speed but don't know how to set up my marker to take the middle one. people have said not to use the large one as it makes the marker unreliable! is this true?
I've never heard of the speed having problems with the large volumiser.
Try this...
Raise the dwell to 17
take out 2 shims (not springs) from the lpr (right side as you look at it)
put the large volumiser on the left side as you look at it
Lower your input pressure to 350
Chrony the speed.
I have to confess to once having done the classic Angel 'shooting the LPR piston, spring pack and shims across the room' trick. It was in my early days though and I hadn't been teching long... that's my defense and I'm sticking to it!