For some time, I have been using 1971 Caprice heatercores when I wanted to use 2-4 120mm fans for some serious cooling power. The problems with that core (barbed fittings that are a royal pain to get out and odd shaped holes punched into the top tank) led me to search for a different core.
After scanning through tons of heatercore specs, I decided to give the heatercore for the 1977 Pontiac Bonneville (with a/c) a test run if the price was right. A quick call to autozone confirmed that it was a heatercore that they normally stock and with a great pricetag of $17.99 this one looked like a sure bet for replacing my caprice cores for future mods.
Quick run down of the specs:
10-3/4" X 5-5/8" X 2" w/o the tanks
about 12-1/2" X 5-5/8 X 2" with the tanks
to put the size into perspective, this is the '77 Bonneville core with 2 120mm fans laying on top of it:
Almost perfect.
On to other good points of this core...
One of the best things about this core are the holes in the tanks for the fittings. They are not odd shaped oval bastages like the ones that are punched into some cores. Instead, they are almost perfectly round and their size makes the switch over to barbed fittings much easier than you would expect.
Pic of the top tank with the factory tubes:
^nice round holes -- that are the same size.
As I mentioned earlier, the caprice cores that I had been using started causing problems as the tubes were barbed -- they are almost locked into the tanks and it is very hard to get them out without cutting, drilling and some torch work -- when they are gone, they leave nasty oval punchouts that are a PITA to seal up properly. Due to the barbs on the factory tubes, if you try to heat them up and yank them straight out, it will tear the brass on the tanks - another headache. I halfway expected the tubes on the 77 Bonneville to be barbed like those on the caprice cores but this is not the case -- a little torch work and some vise grips gets them out cleanly.
^1st fitting came out cleanly with just a little solder residue left.
For those that have never taken a torch to one of the heatercores: you have to be careful with where you apply the heat. The top tank is held on with nothing but solder. If you overheat the tank, that sucker will come right off and it is very hard to get it back on without leaks.
To avoid overheating, I 1st filled the heatercore with cool water. Then I wrapped most of the top tank in soaking wet paper towels (check the above pic). Just to make sure I had everything covered, I then wrapped the core area with a insulating plumber's wrap -- several water soaked paper towels would work in place of the wrap.
Once you have the tank protected from excessive heat, apply heat with the torch directly to the tube where it enters the tank -- like this:
^If you look in the right hand side of the (fuzzy) pic, you can see a vise grip locked onto the tube. Once the solder starts to melt, try moving the vise grip side to side a little - once all of the solder becomes liquid, a bit of side to side action and a straight pull with the vise grip will pull the tube out cleanly.
both tubes out with no probs:
on to the really nice bonus you get with this core -- the pre-drilled holes are perfect in size for a 3/8" npt tap. If you buy 3/8" npt x 1/2" barbed fittings, this is a piece of cake. Just thread the existing holes like so:
Then screw in the barbed fittings. To make sure there are no leaks whatsoever, you can add some JB Weld to the threads and then let it dry or use the torch a little more and silver solder the fittings in place.
before sealing the fittings in place it looks like this:
I will try to cover making a shroud for this core soon:
the one pictured above is still a work in progress but it should be finished soon.
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