I got a new water pump for my 327. It had this pin inside the box. What is the pin for? is it for the third hole on the bottom of the mounting flange ??? never saw it before.

 

Never seen a pin used on a sbc water pump before. How long is it? Is it long enough that you can use it as a temporary locating pin in one of the mounting holes?
You don't want to block off that passenger side "third hole". That's a bypass that flows coolant up to the passenger side head, and across the intake manifold. Without that bypass creating movement, the heads could develop hot spots when the thermostat is closed. Big blocks on the other hand, don't have that internal bypass, and instead have a short bypass hose that runs from the pump to the front of the intake manifold.

 

some of the water pumps have a pin to help line it up. wonder if thats what its for. found some pictures,

 

Which is what I was suggesting. Don't need it though, you can install these pumps with your eyes closed, and the mounting bolts are long enough to guide it on without squirting the gasket.

 

isnt there a pin in some of the shaft ends where the fan mounts. seems like i remember something like that. been a while from working on an old 327

 

I've never come across one, and I've worked with both long style and short style (what he has) pumps.
The fan/pulley is held on with 4 bolts, don't need a pin. You can put those together with one eye closed!
I'd like to see a pic of his pin, to see what size it is. If it's the same as what you posted, that's a "locating dowel".

 

Probably some worker in China or Mexico laughing right now after he dropped that pin in the box!

 

lol. Stop the project in it's tracks...what's this pin for? Seems to have worked!
I'm curious if maybe they drop those pins in the box with every pump of that type, no matter what the application. The newer serpentine belt type engines take the same type of pump, only they're reverse rotation (not reverse flow) and the vanes are pointing opposite, still have the same internal bypass though. I'm not sure if the Vortec engines use the same pump body, but that block doesn't have the bypass. Perhaps the pin is for those engines, and the workers put the pin with all pumps so that they don't have to read (if they can) which application that pump is packaged for?

 

I never saw a pin like it either, hence my asking. And ive done both long and short style pumps. (mostly long though). but yeah, i just left it out. Pump was from NAPA. seems to be working fine. Maybe chow yong fat put the pin in the box.