Friday, October 3, 2008

Hemi Tech- Fitting an SBC water neck to your Hemi

So here's my quick simple tech on fitting a Small Block Chevy water neck to your early Chrysler Hemi. Why would I want to do such a thing, you ask?? I'll explain...

Reason #1: Early Mopar water necks are mostly straight up. In my case, my car is channeled 4-inches, so the top of the radiator is alot closer to the top of the engine than would have been if I went with a "High Boy" stance for my hot rod. So, I really needed something that was right angle and could shoot off to the driver's side. No such animal exists (that I could find) to do just that in the Mopar water neck world. Which leads me to my next reason...

Reason #2: Availability of different angles and styles and the hole pattern is the same.

Reason #3: I didn't have one at all.

I found an SBC water neck that had just the shape I need. The problem with using a GM water neck is they don't have a recess for the thermostat, like the mopars do. So, I picked an o-ring type which had me half way home already. No mill required, but that would have been handy if a mill was off in the corner of the shop that I could clamp down on. But, not the case here. I just used simple air tools. A right angle grinder setup with a 100 grit disc and a cut off tool. The discs are close to the same size as the portion that's being removed, so they worked great for material removal. It's important to be very careful here. Don't nick the surrounding housing or you might not get a good seal when the system is pressurized. The idea is to just take off enough so the lip of the thermostat can sit flush with the bottom of the housing. Go slow, do trial fits, check for flatness of the seat your making for the thermostat.

Something I chose to do when I was modifying this neck was to take a little off the surface of the clamping ears so I could get a little better clamping force on the water neck when it gets tightened down. Only like .003 or so. Taking too much off could crack the housing if it's tightened down too much.

When you're done fitting it, you can use a smaller o-ring than what was provided in the groove that's still there, or you can just goop it up to create a seal.

NOTE! A Mopar style gasket must be used on the water crossover/thermostat housing itself. An SBC gasket will not fit correctly on the water crossover and may actually have a tendancy to slip into the water neck when tightened down. I used the stock replacement as provided in my rebuild kit or available at your local autoparts store.

Hope this helped someone.

Something's missing.... hmmmm...

o-ring style water neck. Bottom view

Thermostat is larger in diameter. The diameter will have to be cut down slightly

Tools to do the job.

Don't take too much off. Just enough to drop it in and stay centered.

First test fit. More material needs to be removed.

finished product. The smoother lip, the better.

Here's what you've got

Goop it up or use an oring with a smaller cross section diameter.

Bolt it up! DONE!

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