54 GMC 152-24 Truck with a 54 235 engine. When I had the 6v battery couple years ago, I checked the compression which was around 95 give or take on cold engine. After that I poured some fuel down the carb, it started up right away with no hesitation. Did not have a radiator on it at the time, only ran maybe 15-20 seconds and sounded wonderful. I was happy, till some people got on my case about a few things such as priming the oil and checking the valves. Before starting it, I checked all the valves while moving the fan blade by hand, all good and they looked wet from oil after sitting for 40+ years. So I pulled the dist and primed the rockers, all the oil is going thru the holes. Yes, it's the original oil as well, looks clean. Yes, I will be changing the oil and filter soon as I find some oil filter lines.
My question, reading somewhere that I can start the engine on a 12v battery, except for the coil which needs to be 6v, I can disconnect everything else. If easier, I'll just buy a 6v battery. I just want to test the engine and see where it is condition wise. Or am I better off to just pull it and rebuild it?
My original plan was to get the truck running to drive it locally, but I am starting to see some other issues that is starting to become major such as complete tear down and rebuild of the truck. I want to keep it as stock as possible, but do have a rebuilt 383 engine as backup if the 235 or 248 engine not good, then I'll have to do the necessary upgrades. Trying to avoid due to limited funds.
You can start it with a 12v battery, you just need to disconnect it as soon as possible after it starts. I had a 6v vehicle that had a good engine but had not been started for over 20 years. After some prep the 6v engine would barely turn it over. Not enough to fire. We jumped it with a 12v battery multiple times to start it and get it in good enough running condition it started to fire using the 6v battery.
