So I noticed a nice spot of brake fluid under my car; after banging my head against the wall a few times I found that the leakage appears to be originating from the screw between the two lines (see photo). This was a brand new cylinder, bad copper gasket? Any suggestions? It's fairly tight already

I've already contacted the manufacturer to see what they can do. I'm assuming I can get a new gasket, but I'm really trying to figure out what that screw is for (Bleed screw maybe?).

 

Your MC actually has 2 pistons that work in series. I think that screw holds them in place after assembly. I personally would not feel comfortable removing it for any reason.

Is that a 15/16" MC? I've got a nice rusty non-leaking one that you're welcome to

 

It does have two pistons, and that wasn't the answer I wanted :/ ... As stated in the earlier post, it's actually a 1" but it was suppose to be a 7/8". Certainly been a thorn in my ass. I may have to take you up on that offer.

 

You probably won't want to hear this either, but after reading numerous threads/posts regarding your master cylinder change, ie; pedal travel, pressure that doesn't seem right, leaking, etc, etc.

IMHO I would contact whom ever you purchased the master from and see if you can return it.
Being you have a 2WD and no other brake mods I just think it would be to your benefit to use 7/8 bore size master cylinder that is for your application.
You won't have to adjust pedal travel, you shouldn't have to bleed entire system or mess with LSPV if it even has one.
Just a suggestion/good luck

P.S. No insult to RustBucket, I think it was a nice gesture

 

If that's a new MC, yeah, take that sucker back!

 

Alright I caved... I'm working on getting the 1" one returned. I have the correct sized replacement in the mail. For future reference rustybucket was correct; according the Cardone that screw keeps the #1 cylinder in place.