I have been fooling around with several '30's GMC trucks. Generally speaking GMC used Oldsmobile and/or Pontiac flat-head 6 cylinder engines prior to '39, when they came out with their own line of OHV 6 cyln engines.
I have a complete '37 Olds 230 cid engine that was a running engine when I pulled it out of a '37 T14 over ten years ago. Wm.
Excellent information, thank you. The data plate on the engine says its 3-3/16 bore and 4-5/8 stroke and under 'type' it just says '221' luckily its still very readable and on the lower block, and of course its marked General Motors Truck Corp. The engine that we have is an OHV and not a flathead. The manual we have from GMC about this truck does talk about this 221 engine however, so I am at least pretty sure its the original engine. If its really an Olds or a Pontiac in disguise I would not be surprised. Ill have to look in that direction for more information, soon Ill need to find a remedy to the rod bearings which are damaged pour in place babbitt bearings, but the mains are steel backed. Im sure finding these parts will be an adventure in itself.
Thanks again for the info,
Matt
