Hi,
I assemble my rebuild 425 and want to overhaul the oil pump. The kit includes also the valve spring. But I'm stuck, because I don't know how to get the spring out of the body. It looks like there is kind of retaining ring? Didn't see such a construction before.
Any hints?
Thanks
The plug is easily pried out with a small screwdriver. It is reusable and is securely supported when the pickup tube is bolted on. I would recommend using blue Loctite on the pickup tube bolts.
Shimming can be a bit more interesting. Most pumps can be shimmed with washers of an appropriate size. This pump has spring guides in it and the retaining plug is designed not to go in farther than the guides (actually it is a loose fit and should be considered set when support flush with the pickup flange). You could make a shim which will fit on either side of the retainer, but you will not gain much pressure. If you want to gain some pressure I would recommend finding a suitable replacement spring which can be modified. If you want to build a shim the ID should be larger than the pickup tube witch is about .485". So aim for 1/2" hole minimum.
You should also look at the condition of your cover plate. When working on oil pumps pretty much everyone recommends lapping the cover plate. The nailhead cover plate is steel, so a bit more of a challenge than a cast iron one. Depending on the depth of the grooving, I sometimes put a fine belt on my 50s belt sander and carefully rotate the plate until it is close to cleaned up. Then use a more conventional method of cleaning up.
Take a piece of flat glass, start with a piece of coarse emery cloth and flood it. Rotate and work the plate around in an 8 until things are cleaning up, then move to a medium emery for finishing.
Thanks a lot for this detailed description!
The way I do the pumps is cleaning up the casting flash inside on the cast pumps for better oil flow. The aluminum pumps are more finicky but, some people like those better. For the pick-up tube you can use a larger pick-up tube which I have available. I RED Loctite the bolts & safety wire them. They have known to get loose. NailHeads don't needs gobs of oil pressure because of the oiling design. Even racing & taking them to 6K + RPM's no more than 50-55 pds. is more than enough, & that's challange. It's pretty easy to get 45pds otherwise. MOST stock applications run for hundreds of thousands of miles with only 32-38pds.
This is ALL stuff I DO to "Nail" pumps when I blueprint them.
Tom T.