MS460WOODCHUCK
Addicted to ArboristSite
I believe an 8 pin would be less torque more chain speed opposite for a 7 pin. I would tend to stick to 7 pin with 18" and over bars. Less than 16" you might could get away with 8 pin on a 3700.
You would not want to run a 8 pin on that saw. 8 pin to me are for a 70-80cc saw with a 20" bar. This is my opinion others may say different.