Oil Pump Feed Fitting Replacement

[Tomsan]

This is for a 1946 HD UL with the cast iron, 3 valve pump. I need to replace the pump inlet fitting where the feed line enters the pump from the oil tank. Current fitting has very worn threads and the end that is tapered is shortened. When I thread the feed line all the way onto fitting, it is a loose fit, so that the flared end of oil line does not seat on the inlet fitting.

Colony makes a replacement fitting, part 2374-1 (also V-Twin 40-0512). The replacement fitting has 7/16-20 straight threads with an internal hex for installation. I understand the replacement method is to angle-grind off the old fitting and then drill the old hole with 25/64 bitand tap it.

Does anyone have any experience doing this replacement and any suggestions or tips?

Thanks

[duffeycycles]

I've done a few & they are pretty easy,but I am very skilled with drills,taps,grinders & files.
The new part is more durable than old cast iron.Nochunks of metal in the feed!

[dukekleman]

I have done them as well and agree with Duffey. I personally like to use my mill machine, spot it off nicely, drill with the mill and then tap. If your careful, patient and skilled Im guessing you could do a nice job in a drill press or possibly free handing it. They do make drill jigs for aiding in drilling 90 degrees X&Y.
I use them occasionally for Heli coil drilling procedures and they work pretty good.
Hope this helps

[T. Cotten]

...Does anyone have any experience doing this replacement and any suggestions or tips?..

Back before the Colony offering, Tomsan,

And even before I had a digicam,

We lathe-turned the hex off a 63533-15, leaving a little nipple to center it, and silver-soldered it to the dressed body, or whatever.

Don't think I did but a few, but they were strong and invisible.

....Cotten

[Tomsan]

Thanks for the comments.

How easy is it to cut that existing old cast iron inlet fitting? My concern is an angle grinder might be unwieldy on that small fitting. I have a cutting wheel on my Dremel that would be easier to control. Any thoughts on that?

Don't have a mill machine. So I'll have to do by hand. I have a new 7/16-20 NF plug tap and new 25/64 drill bit.

So my plan: Put the pump in angle vise on my Delta drill press. To get alignment, best I can do is adjust alignment by using shank of a test drill bit or rod inserted into pump inlet channel/hole. That will make a vertical shaft coming out of the pump inlet that I can use to adjust pump position in vise to align/parallel the shaft with the cutting bit in drill press - all prior to drilling. Once aligned, move pump under drill bit and center it over hole, bring bit down without turning on drill to center it. Then take it slow and drill just depth needed for the threads in new fitting. Maybe 1/8" deeper to get threads all the way?

Past tapping I've done has been by hand. I follow what I learned in HS metal shop: start half a turn in, back out, then try to go a full turn, back a half turn, repeat the full turn in, half turn out. May go less than a full turn depending on how cutting feels. Keep it oiled. I suppose I could put tap in drill press chuck to get same alignment as recently drilled hole, but NOT turn on drill press (I believe I'd pull plug). I can turn the tap by hand turning the drill press chuck.

Does this sound reasonable?

[dukekleman]

Sounds like you'll do fine.