I have my 1911cc engine rebuild coming along well. Everything is disassembled and off to various machinists and rebuilders. I have the replacement parts sorted out for the most part, but the thing that is giving me the most trouble is the oil pump.

I've read many, many forum posts here and elsewhere but clarity is elusive. It all boils down to the following:

* Melling and other new replacement Type-1 pumps are generally disliked.

* Aluminum bodies are better than steel to maintain an even expansion rate.

* Schadek Type-1 pumps are of decent quality, but the OD size is slightly too small for the engine case. They can have a groove milled into them so an o-ring can be inserted, but I don't own a lathe. Nor do I have the skills to do it much in the same way my do-it-yourself surgeries have failed. When I approached a local hot rod machinist about the modification, he said he wouldn't touch it and gave me a disapproving grunt.

* Original Type-4 pumps can be rebuilt, but I fear for wear and I have repeatedly read about oil leaks and Jake Raby swears against them. One of my design goals in the rebuild is to not have leaks or engine failures.

Nearly every post I've read here and elsewhere refers to an article explaining how to modify Type-1 pumps (http://home.att.net/~airdoc/T1oilpumpmod.html) but that page has been down for years. Archive.org has a copy, but not with pictures, so it's useless.

So here, in the year 2015, can someone explain to my handsome self what I'm to do?

Thank you, space jockeys.

-m.

1)Pump holes need to be properly aligned with case holes in order for that to work.

From what I have seen, the type 4 stock pumps are the only ones out of the box that are close to lining up properly, and even those can sometimes use a port matching session to get them perfect. So, the holes in the side of the pump need to have a clear path to the holes in the case, and that means you have to take the pum apart and ream those holes out to match.

2) If the pump is too tall, the cylindrical portion, it will hit the bolts on the cam gear.
You can grind down the head of the bolts, or shim out the pump body....or both.

3) The tine on the end of the pump is too long and will not let the pump sit flat to the case, and can bind the camshaft and push is back, all bad stuff. Grind down the tine.

4) the aftermarket pump bodies sometimes are too small in diameter to sit in the hole correctly....I think that is an matter or research to find the one that is right......


All of these things have been solved over the years, so YMMV depending upon the pump you choose.
The stock pump, ported, will serve you fine for the lifetime of the motor....just my opinion.