Swapping in a Custom Radiator

radiator in place

54 Radiator in place and ready to pressure test.

I was planning on using the original 54 radiator, as it's in pretty good shape. There are three problems with using it with the Chevy small block. The first is the radiator has the coolant intake located in the middle of the top reservoir, it has no provision for tranny cooling and the intake tube is only 1" diameter. I have a few choices that I can do:

  • Modify the rad (lots of work or money)
  • Add a aftermarket tranny cooler
  • Go to the wreckers and see what I can find.

My original idea was to add the biggest aftermarket tranny cooler to the front of the radiator. I talked to a few experts on trannies and all agreed that aftermarket tranny coolers by themselves will not sufficiently cool the tranny. Heat is the worst enemy of transmissions and cutting corners like this is a sure fire way of burning them up.

So it's off to the wreckers with the radiator dimensions in hand. I found that 70s Nova radiators are close in dimension but have the inlet and outlet hole located at the wrong corners. Several 60s Fords were close but then came across a mid 70s Dodge pickup that was almost an exact fit. The 54's dimensions were roughly 23"x23" while the Dodge's dimensions were 23"x22". It was 1 inch narrower and pretty much the same height. The upper rad reservoir is flat across the top versus the 54's shape. The inlet and outlets were the correct size and location for my application and it had a tranny cooler built-in.

two rads

Engine side view: the mid 70s Dodge rad is on the left, 54 rad on the right

Interestingly, the vehicle that I pulled it off of, didn't have the tranny connected to the rad. Instead, it was connected to a very small aftermarket tranny cooler located in front of the rad. I suspect that the previous owner couldn't remove one of the lines cause it was frozen solid. I ended up removing the line and fitting from the rad. Most likely the tranny burnt out from overheating cause the aftermarket tranny cooler was only 3"x8" in size. It'll be perfect for cooling the rack and pinion (unfortunately, it was gone when I went back to get it). Anyways, I blew out the rad's tranny cooler coils with my air hose to see if it was plugged but everything checked out fine. In fact, it looks like it was never used as nothing but air exited. I will be installing an aftermarket tranny cooler so I replaced one of the fittings with a hose coupler.

rad flange

Comparing the front mounting flanges (Dodge on left, 54 on right)

The Dodge's rad has to have the mounting flange modified so that the mounting flange sits flush with the front of the rad. Currently, the rad sits at an angle back about an inch at the bottom and 2" at the top from the mounting frame. The Dodge also has a very large reservoir on the top compared to the 54's. It overhangs the front of the core by about 1". I mounted the front end together cause I got tired of working on the mechanical. The good news is that the Dodge rad fits perfectly and clears the hood latch mechanism without any problems.

cut out

Here's the side view with the excess flange cut off

I used my die grinder to cut off the excess flange and then had to find something to use as a bracket to hold the rad to the frame. I was looking for some angle iron when I realized that the flange that I cut off was the exact right size and just needed some trimming to fit. I cleaned it up and painted it and it looks great. I'm using the fan shroud mounting bolts to bolt the new mounting flange to the rad. I'm thinking that I should weld it though as it may not be strong enough.

front view   rear view

Front and rear view of mid 70s Dodge pickup rad installed - Looks like it was made to go there!

I was cleaning up the garage last week and came across a thermostat housing gasket and put it in a safe place. Well do you think that I could find it? Two days later I came across it resting on the battery in plain open view after searching through every drawer and nook and cranny. Go figure...

I cleaned and painted the radiator frame black and bought new carriage bolts for the bottom. There is a neat little metal piece that holds the carriage bolts in place at the bottom, I painted it silver. Between the radiator frame and chassis, I put a rubber pad. I remember it being about 1/4" thick when I took it apart, so I will probably need a thicker pad, won't know exactly how thick until I put the front-end back together.

Radiator mount

Radiator frame in place

Radiator carriage bolts

Carriage bolt holder

Went to the parts store and the partsman was determined despite my objections to look up rad hoses for a 1954 Pontiac with a 1976 sbc in his parts books and on his computer. Finally, he gave up and said just go in the back and look. So away I went.

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Copyright July 2011 Eugene Blanchard