[Jeff Chambers]

I never install a pump without 'blue printing' it first. That means taking it completely apart, deburring it, cleaning it and checking clearances. Got too much time and money in any motor not to spend a few minutes making sure it'll get the life blood it needs. Also, for the Mellings, run the 10687 pump. It has a cast cover and a gear rotor with stub shafts both top and bottom. The bottom one extends through the cover so that the gear rotor isn't cantilevered. It also has an adjustable relief valve. There's absolutely no need to run a high volume or high pressure. I spin my motor to 8000+ on every pass and have never had a pump fail. Also be sure that you've got adequate oil pump shaft free play WITH the distributor installed. If you're binding the shaft, the pump will fail in short order since you force the gear rotor against the bottom cover, wiping out the oil film clearance. Pick-up clearance to the bottom of the pan should be 3/8" to 1/2". There's something happening here if you're killing pumps like this.