225 oil pump

I read your oil pump tech article Sparky. You did mention your gears were to tight. I would expect problems too. Plus I'm sure a fresh pump with good clearances and minimal wear would do the job just fine. I have not had the gear wear problems mentioned. I did have a difficult to diagnose problem with my cam walking back and forth. That did some damage but it was fixed years ago. 2 years ago I blew up a piston skirt. My distributer and cam gear looked excellent. I'm not trying to be the devils advocate here but I think the HVP is getting a bad wrap. When they are set up with no drag and proper clearances they do work. And I do know that buicks have marginal oiling systems. So run what works for you and thats the best thing. If I am still on this forum next time I take my engine apart, I'll post pictures of my drive and driven gears. I guess I'm just lucky.
No worries man...

 

I installed the Melling unit back in '88 or '89 when I installed the 231 in my CJ-5. The motor has had 0 oil pressure issues since then, runs 25 psi at a hot idle, NO cam problems, NO distributor gear issues. Ran one in my first race truck with a STOCK Buick 350 motor also with no issues. I spent lots of time trueing the timing cover and oil pump cover and triple checking all clearances however. I suspect most of the people having issues have a housing distortion issue or clearance issue when setting them up with the right bypass spring and checking all the clearances. I've found it's real common for the bypass piston to get partially stuck in the bore due to wear which can lead to the exact problems discussed in that article. What happens is the bore the bypass piston runs in wears and the piston cocks slightly and hangs up intermittently giving too much oil pressure when unwanted.
I have to agree with Jeepdaddy and Kaiser Jeeps on this one. The key to making is working is thoroughly checking all clearances, for smooth operation, and making sure the bypass piston bore is in good shape and the piston moves smoothly with no hang ups. Just my .02$ worth, ymmv, etc, etc. Nickmil

 

Many GN owners race stock oil pumps if setup properly. I also used the TA kit to get it within spec.

I had flat file the 60% of the mating surface to knock off enough mils to meet minimal tolerance with the feeler gauge. My stock pump was actually uneven from the factory. After filing gently, I had ALOT of figure 8 sanding on a panel of glass.