Looking at this 1948 GMC, and I'm a little unsure about harmonic balancers. What's on there now (first pic) has a pulley, with an extended center section of slightly smaller diameter. It's the same depth as a 235 balancer, but not as big around. And it has four "extra" bolts stuck in it. As this came from a 1.5T fire truck, I'm wondering if it may have had a second pulley in front of it for accessories in a previous life. Or, am I missing part of the balancer itself? I read that Chevy 235 and GMC balancers interchange, but my Chevy balancer (blue one) has a larger face diameter; and a narrower pulley groove. All thoughts welcome. What have I got, and what do I need? And thanks, y'all.
Crank Pullies O.K. , this one is interesting ; Fire trucks often has front mounted water pumps that ran directly off the crank so NO damper , just a thing bolted on that looks like a ' starting dog ' Clearly that one uses the wider (? 5/8" ?) V -Belt you don't want to use unless you have to due to water pump and generator pullies also being 5/8" . Maybe some more photos would help ? .
Big trucks often had multi groove pulleys for a number of reasons. The most common was for an air brake compressor but have also seen auxillery pumps, 110/220 generators, etc. We had a tree company truck that had what looked like an over sized generator with 110v plugs (they worked). I wish I had a dozen of those balancers with so many wanting p/s and a/c.
Bigger is better! Everything looks the same except for the flywheel. Mine has 6 rivet like things sticking out of the front, and you can clearly see the arms that stick out for hand cranking the engine with a bar. (At least that's what I assume they are there for.) Obviously something was bolted to the front, since you have the bolts and lock washers still there.
Tried getting it started today. Turned over smooth. Good oil flow from the rockers. But no fire. I'm not happy with my electrical setup in my test area (motor's not in the truck), so need to do some work there, then make sure I have spark. Did plugs, wires, cap, rotor already. Will throw in a new set of points and maybe a condenser, then see if I can't get it to light off.
Engine Testing Sounds like a good plan to me . Before EVER replacing an ignition condenser , always look at the old points ~ if they're pitted equally or close to it , on both sides , stop ! you have the holy grail of kettering ignition systems : a perfectly matched condenser ! . Be sure to drain out the oil oil and replace with fresh thin (cheapo is fine) motor oil and adjust the valves . When (not if) it begins to cough to life , remember to shut it off after a minute or two ~ running it sans coolant , even for 5 minutes , creates hot spots that damage things really quickly . Doesn't matter if you plan to rebuild it , DON'T RUN IT SANS COOLANT ! .
Thanks for the insights, Nate - No worries about the coolant, I hook up and fill the radiator before starting. Had to swap a 235 T'stat outlet onto it so my hoses would fit, but it's good enough for the little bit of running it'll see now. I'll swap back and sort out the hoses when I get it into the truck.
