Water pump housing fitting sizes 1/2” and 5/8”

[JCJones]

I have a 69 Barracuda, and I’m building a Strong 383 for it. It was originally a 318 car.

I bought a big block water pump at a swap, installed it last Fall, and went to screw in the new fittings today and realized the holes in the housing are different sizes, and, of course, the fittings I bought are both the same size. The casting is 2780987-8. My research tells me it’s a water housing for a 1970+ big block. Pre 1970 housing holes are both 5/8”. I’m assuming one is for 5/8” hose and one is for 1/2” hose.

I really don’t want to buy/install another housing at this point (later, yes). So I’m thinking I can run this housing with no problems, but I’ll just need an adaptor before attaching the smaller hose at the firewall?

Also.. originally an AC car, but I’m not hooking that up.

Anybody have thought, confirmations?

 

[krazykuda]

The threads are most likely pipe thread...

I would say 3/8" or 1/2" pipe thread...

I am setting up a small block and had to buy some nipples... Granger had the exact ones that I needed once I figured out what pipe thread and diameter hose nipple that I needed... They ordered them for me and I got them next day...

 

[JCJones]

The threads are most likely pipe thread...

I would say 3/8" or 1/2" pipe thread...

I am setting up a small block and had to buy some nipples... Granger had the exact ones that I needed once I figured out what pipe thread and diameter hose nipple that I needed... They ordered them for me and I got them next day...

Correct... I believe the threads are 3/8” and 1/2”.

 

[TrailBeast]

I have a 69 Barracuda, and I’m building a Strong 383 for it. It was originally a 318 car.

I bought a big block water pump at a swap, installed it last Fall, and went to screw in the new fittings today and realized the holes in the housing are different sizes, and, of course, the fittings I bought are both the same size. The casting is 2780987-8. My research tells me it’s a water housing for a 1970+ big block. Pre 1970 housing holes are both 5/8”. I’m assuming one is for 5/8” hose and one is for 1/2” hose.

I really don’t want to buy/install another housing at this point (later, yes). So I’m thinking I can run this housing with no problems, but I’ll just need an adaptor before attaching the smaller hose at the firewall?

Also.. originally an AC car, but I’m not hooking that up.

Anybody have thought, confirmations?

If you have a hardware store that carries the Sharkbite plumbing those adapters work great.
They have the two ridges around the slip on ends that work well with hose clamps and have threaded tube to pipe thread adapters of multiple size combinations.

 

[69_340_GTS]

Why not just get the right fittings? An adapter is just one more place to spring a leak someday.

 

[AndyF]

I have a bunch of cast iron housings. I'll look to see if I have an early date code. If so you can have it but you'll need to pay the postage. I threw some cast iron housings away recently when I was cleaning up but I think I still have some stashed out in the shop.

 

[Daves69]

This maybe?........
https://www.amazon.com/dp/B0131COA5Y/?tag=fabo03-20

 

[JCJones]

This maybe?........
https://www.amazon.com/FasParts-Brass-Straight-Male-Hose/dp/B0131COA5Y/ref=sr_1_4?ie=UTF8&qid=1521419819&sr=8-4&keywords=3/8+npt+5/8+barb[/QUOTE]

Yes... i think this is what I'll do, thanks!

I guess my main question was... do i need to be worried about the smaller diameter hole in the pump housing... i'm assuming I don't, but was just looking for some confirmation.

Thanks everyone!

 

[69_340_GTS]

You won't need any adapter. The pipe thread to hose barb fittings come in any size combination you want. For your application both of them need to have the same size hose barb on them. But one fitting needs to have 3/8 NPT on the other end, and one fitting needs to have 1/2 NPT on the other end.