Well I finally swapped out the stock 1st gen water pump with the newer s5 aluminum set up. I thought it was a simple swap but as always there was a few mods thats had to be made due the fact I'm using the 12a front cover. One is the grinding away of the back of the s5 pump housing at the botton bolt, 3/4 of aluminum grinded away then the hoses are a bit different, had to mix and match hoses to make it work. Also an end coming out of the s5 thremostat housing had to be plugged. Wish I had taken pics but I didnt. No big deal as far as HP goes but its newer and looks good.

 

The most involved I've ever gotten has been with an S4 T2 waterpump. It still has the dual bolt pattern on the thermostat housing, so I could use my old aluminum (pot metal?) one with the threaded hole for a temp guage. The pump had a CLT sensor on the back, which I left alone, a blank casting for an aftermarket guage if I wanted to add one, and a thermowax nipple all next to each other. The lower rad hose fitting is in the same position as an NA S4, which is a few mm shorter than a cast iron waterpump, so you need to adjust your lower hose accordingly. The S4 T2 waterpump has another thermowax type nipple right next to the lower hose connection, which also had to be blocked.

The most important mod you need to do in order to install one of these waterpumps is you must grind some aluminum from the back to clear the 12A front cover.

I installed an S4 T2 waterpump on my aweseome '74 engine and took it for its first test drive today. It ran cool.

Latin, it sounds like you got everything figured out for the S5 pump. What did you think about the three bolt thermostat housing? A little different, huh? It's plastic too.

 

S4 T2


And now it fits.

 

Yea Jeff the thermostat housing is a bit different then what most of us here are use to but the weight difference is what amazed me the most. That entire pump/pump housing only weighs as much as a fb water pump alone, and because its mostly aluminum, rust isnt an issue.

 

Looks like I have to pick up one of these for myself ... Is the S4 and S5 about the same weight? Sucks that I find out about this just now after I got my water housing machined for the 3/8" NPT ...oh well whats another 20 bucks

 

humm i dont see why grinding was involve i did this for mine and it was direct bolt on take a look.

http://s39.photobucket.com/albums/e1...arparts047.jpg

 

i tried an s5 housing on my 12a and i couldnt get it to work, it was hitting the main pulley. the s4 one bolted right on though, just had to drill out the back of one of the holes and run a bolt of the correct length through.

 

You don't need to grind the back of an S4 NA.

Yes you need to tap some threads in the waterpump housing and drill the impeller hole larger to accept a bolt or stud. I'd say 10mm x 1.5 (coarse thread because it's in aluminum).