I bought an aluminum water pump housing from 440 source for my 440. It was a blemished model because one of the ports is slightly smaller than should be. They say its fine to use as is or if you like, you can dremel it out a hair, like porting heads. What is a good dremel bit to use for this? The 2 stones i have clog up with aluminum real quickly..

I have heard nothing but bad things about those "too small port" 440 Source housings, I would NOT use it even after opening it up...

what have you heard?

use trans fluid on the cutter and it wont clog.

Probably yet another example of Chinese parts crap.

Blaster works even better than atf. Chalk also works wonders if you want to do it dry.

blaster as in PB blaster? I too have one of those discounted housings & I'm for sure gonna hog it out/keep tabs on flow/temp to see if I got a smokin deal or not. EDIT been awhile since I eyeballed it but this thread reminded me that I was maybe gonna open an access hole in the side to get in there then cap it with an NPT plug.

You should buy a course carbide aluminum bit and use candle wax to keep it clean when it starts to clog
Be careful when you start cutting with one of them, they cut a lot in a hurry

Funny how things get twisted around...
440Source tried to clone the Mopar Performance water pump housing, unfortunately in their development tooling/sourcing process nobody checked the internal passages' dimensions....
And the China factory went into full mass production, and 440Source received a full shipment of water pump houisings, once sales started the negative reports started pouring in the Mopar engines were overheating..

Next 440Source was well aware of the problem and gradually modified the tooling by enlarging the internal passages. Unfortunately 440Source was stuck with a pile of the original defective products...

Just my $0.02..

Yep, PB Blaster. I used to use it way back when on aluminum heads. Hopefully whatever comes in the spray cans hasn't changed too much in the last 45 to 50 years. Actually hadn't realized how long ago it was that I was working in New Paris. You might call that the good old days, or not.....

Can anybody show a picture of this too small port and what it should be like?

The easiest way to check is to insert a finger into the lower hose opening, if it is tight then you know. I just sold an MP unit this week, I could almost put two fingers in the opening...

1. Don't use stones on aluminum. Use carbide burrs.
2. A Dremel will take forever and I doubt that you can reach in far enough with any bit that will fit in a dremel. Borrow or buy a die grinder that accepts 1/4" shank bits. Either pneumatic or electric. You can get a cheap one at Harbor Frieght that will work.
3. Several posts have already mentioned what to use on the bits to keep them from loading up with aluminum. Pick one. They all help.
4. Don't use stones on aluminum.
5. Whoever you talked to at 440source is an idiot for suggesting that you could fix this with a dremel.
6. Did I mention, Don't use stones on aluminum.

I buy it by now the gallon with a coupon from advance auto and add a little transmission fluid to it

I "had" one of those pumps. You can open that up to at least double the current size but there is a turn in the port and you'll have a problem going much past it.

For what 440Source paid for those I think they should have scrapped the lot and saved themselves all the bad press.

Whether or not there were any "real life" issues due to the pump themselves is hard to say. You have to figure that someone putting on one of these pumps has done other mods too - which could cause overheating issues.

DON"T use stones on aluminum ! this can't be emphasized enough ! i agree on all the above points.

The 120V AC wired Harbor Freight 1/4 Die Grinder has a flaw in that the plastic will crack near where the four mounting screws get their internal threaded purchase.

If you line up a drill bit correctly and hold it steady, drilling on through the plastic to the metal frame beneath and using a longer screw or all thread as a stud will strengthen the assembly enough to prevent the cracking.

Sugru moldable epoxy might possibly be used to strengthen the plastic in the weak section.

The formerly $100 Craftsman 1/4 die grinder is discontinued but is a worthwhile purchase at a yard sale if the price is low.

If you look at a carbide burr for steel it has a crosscut cutter pattern. If you look at a carbide burr for aluminum it has a single cutter pattern. That's intended to keep the burr from clogging with aluminum. As to using stones? All of the comments are spot on, don't even try.

I should have pointed out the difference between single cut and double cut burrs. Single cut will cut faster and clog less in aluminum but it also makes long very sharp slivers that can ruin your day. Please at least wear good eye protection with either type of cutter. If you have to go to the emergency room with metal in your eye they will show you their grinder. Real close up!