Tractor Repair: Ford 9n no gas to spark plugs, ford 2n tractor, ford 9n

Question
Hello Arnie, I would appreciate any advice you can give me.  I have a 1940s Ford 2n tractor.  It won't start very well.  I have checked the carb for fuel flow.  It's good.  I have cleaned out the carb and replaced the plugs.  I have a spark on them all.  When I got the tractor, it started, but did not idle properly. I had it serviced and it was found to be a defective manifold.  A new one was installed.  I have tried taking out the plugs, spraying in starter fluid and replacing plugs, still no luck.  It is six volt.  Tried boosting with 12v (not direct to battery of course).  It turned over a little better, but still not well, sounded like it was about to fire but never did.  Starter bendix seems to disengage prematurely before it will fire.  Even after repeated crankings, the spark plugs stay dry and I've heard these tractors are easy to flood.  Why won't it fire at least initially when I have spark and fuel (starter fluid) at the plugs?  Doesn't seem logical.  Could a weak spark be the problem? Is is not cranking hard enough to fire? Compression test reveals only 70 to 80 psi per cyclinder on all cylinders (should be 110). I am wondering about a 12v conversion or wiring replacement or new starter.  Not sure what to do next.  Please help.  Thanks!!

Answer
Hello,

  First of all, if the compression is low as you stated, it is going to be very hard to start no matter how much fuel, spark, or starting fluid you have.  It sounds like it might need a valve job or an overhaul.  Starting fluid can be sprayed into the air cleaner intake without removing the plugs, however it's not normally needed on a gas engine and can be dangerous if there is intermittent spark at the plugs.  I saw an explosion split a muffler wide open and blow out a guy's ear drum.  I recommend that it only be used on diesels.  Here are some other things to check.  Check all the manifold nuts to make sure they are tight.  Since the manifold was replaced they might need to be retorqued.  Make sure the choke is closing all the way.  Make sure the gasket between the carburetor and the manifold is good and the carburetor mounting nuts are tight. If there is a problem with these, you will never be able to get enough gas to it to start it or flood it.  Give it a complete tune up if it has been awhile since it was done.  Points, condenser, distributor cap, rotor, plug wires, etc.  A weak spark definitely affects starting.  Make sure the exhaust pipe is not plugged.  If the gas in the tank has been in there for a long time, it could be stale.  If it's more than 4 months old, drain it out and put in fresh gas.  A gas engine should still fire even if it's cranking over slower than normal.  With a diesel, slow cranking speed affects starting alot more.  The starter will need to be repaired or replaced.  With 12 volts hooked up to it, it should spin over very fast.  The starter drive kicking out prematurely doesn't help the situation either.  When everything else is in good shape, I don't think a 12 volt conversion is necessary, but some people want to do it just to modernize it or because they think it will be better.  Usually, they're trying to compensate for other problems that should be fixed first, and if they were fixed, the conversion wouldn't be necessary.  But that's just my opinion, it's up to you.