M37 Not Starting-Troubleshooting help needed

[Lifer]

I agree with Charles that a compression tesst is in order. To make a gasoline engine run, you need 3 things: fuel/air mixture, compression, and a spark. All three of things must be in the proper proportions and occur at just the right time, or it won't run. Since you have a spark and you have fuel, the only other variable is compression. Sounds to me like you just don't have enough of it.

[rickv100]

It lives!!!!

I was able to spend the last 4 weeks working on the truck on Saturdays. New rings, honed cylinders, lapped valves and adjusted valves.

After a few cranks she fired right up.

I have retorqued the head after I let the truck warm up.

Next I need to adjust the timing.

Rick

[Lifer]

At this point, I'm beginning to suspect a fuel delivery issue. You say that your spark plug was dry when you pulled it, not wet as if it were flooded. Maybe you have a little, tiny speck of crud obstructing the carb jet??

[Joe]

It sounds to me like you're overlooking something simple. Have you tried taking the top of the air cleaner off and putting a tablespoon full of gasoline directly into the carburator? Starting Fluid would be even better since it takes very little spark to ignite it. If it fires on that then you probably have a fuel problem and your ignition, compression, timing, spark plugs, etc are all at least functional even if not perfect. The FIRST thing that I look for in a situation like this is spark from one of the spark plug leads. If I have that then the next thing that I try is Starting Fluid since it completely eliminates the fuel system, including an empty tank, plugged lines, plugged filter, bad carburator, shut off fuel valve, etc etc. If neither of those works then you have to consider something more catastropic such as a jumped timing chain or something that may have drasticly changed the ignition timing. Things such as stuck valves, broken valve springs, holed pistons, etc are possible but they only affect ONE cylinder and shouldn't stop the engine from starting or running.

A compression test is always useful because it tells you about the mechanical condition of the engine regardless of the charging system's condition, ignition problems or carburator issues or fuel delivery problems. BUT in a case like this where an engine was running fine and suddenly refused to start it's unlikely to reveal anything.

[rickv100]

Check my last post, I said it is up and running.

Rick

[Joe]

I saw that. I was explaining how to quickly troubleshoot it to find the reason it wouldn't start. You're not the only one that reads these posts. BTW Did you find out what the problem was or just throw money and new parts at it?

[cuz]

Rick,

Congratulations on getting it running. Looks like the only help you may need yet is timing her correctly. If you do just hollar. Thanks again for returning to your original thread and letting us know you got her going!