Didn't intend to do this for tech week, but what the heck. Pretty much just for the Hemi gurus.... 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 drivers 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 it was time to make one. So, I picked an o-ring type which had me half way home already. No mill required, but that would have been handy and ideal of course, but not an option in my case. Simple air tools will do the job if you are careful and take your time. I keep a couple el cheap-o's setup with different grits just for stuff like this. The discs are close to the same size as the portion that's being removed, so they worked great for material removal. One with a simple cut-off wheel and the other with a 100 grit sanding disc. Here's what I started with. You can see the o-ring groove that will be modified. The Mopar thermostat is just slightly larger than the outside edge of the groove. A little off the diameter will take care of that. After taking a little off, here's where I stand. I just took off enough so when the lip is ground down it will drop in and stay centered. Time to start removing part of the center lip. It's really important to take your time 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. First of several test fits. Here's the finished lip or "seat", if you will. 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 when it's tightened down. When you're done fitting the thermostat and are ready to mount the water neck, you can use an o-ring with a smller cross-section diameter, than what was provided with the neck in the groove that's still there, or you can just goop it up to create a seal. I just used ultra black RTV to make the seal and dropped it in. 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. So here's the finished setup... This got me the line for the radiator hose I needed. Should be able to use an off the shelf hose and just trim it to fit the way I need. I'm super close to getting this thing fired up! I will share when it happens... Hope this helped someone... Cheers Scooter
BTW... For those of you wondering... I guess I should point out that Early Chryslers do not have a recess for a thermostat.
Thanks guys! Just sorting out all the little dumb things needed to be done to get it fired up. I spent a few days bugging Gary (73RR) and Creepy Jack for info. They were a big help getting me the info I needed. I'm sure this whole thing is nothing new, but I needed a water neck and needed one FAST and couldn't find any information out there on rather or not it would work, so I figured screw it, I'll just try it. BTW Pauli.... been thinking about that DeSoto Hemi story you told me about a lot lately!! HAHA!!
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