A 1955 F350 239 Y block is positive ground correct? So.....I'm working on my truck, trying to get it started, and while doing some research I found this out. Will this "fry" any of my electrical components? Could this be the reason I can not get the truck started? I know I'm an idiot for putting it in backwards but it had not been run in over 20 years and the cables appeared to be set up for that configuration. The truck has been turning over and I have spark in all but cylinder #8. Any words of advise would be greatly appreciated. Thanks in advance.

 

Dave, this is a bit confusing. What configuration does it appear to be set up for? Negative ground? Did you put the battery in "backwards"? I mean, did you hook it up negative ground? Is it still 6 volts?. If so, and you used a 6 volt battery, then nothing should be "fried". If you have an ammeter instead of a voltmeter for your battery gauge, then it would be pegged backward if the polarity is wrong (and it's wired right). No spark in only one cylinder has nothing to do with the battery polarity. Sorry I can't be more help.

 

@Joe The cable ends were set up up for negative ground. (6 volt) The thing is my dad put new cable in way back when and I am not sure they are right. I think I might be best to go get new cables that will put it back to positive ground. I just didn't know if hooking it up in reverse would affect the ability for the engine to start.

 

Connecting the correct size battery backwards won't hurt anything. These things are so simple it will only effect the charging.

Are you getting good strong spark on the other seven cylinders? If so, and it is in time and has decent compression, it should start. A fuel problem perhaps?

 

OK, did you know the 6 volt battery cables need to be heavier gauge than 12 volt cables? If it's turning over at a good clip, that has nothing to do with the problem starting or no spark to #8 cylinder. If it's sluggishly turning over with a good battery, it could be the cable thickness or grounds. Good grounds are really important in a 6 volt system.

What have you done to troubleshoot the firing problem? If only #8 has no spark, it could be the rotor cap or plug wire.