I`ve run across this problem several times before with a chevy short water pump being to short, once with my own and several other friends having the same issue over the years, not clearing the stock timing cover, about 1/8th inch or more to short, not sure if its a MFG defect ( off shores) or if they have been thru a rebuilding shop and they have been milled off...you guys have any insight of this, one brand in question was the Stewart brand that someone else had, the name stuck with me for never to purchase...