[cub149]

I am putting the (lift?) valve from an 1862 into an 1860 ported pump. I took out what was in the 1862 pump and going by the diagram it is missing the shims (part # 18). How important are these? I don't know what they are for exactly but it seems they are for how much pressure is let through? Anyway, should I just wait until I get this running and see how well it lifts and then see if I need to shim it? OR, does it for sure need shims?