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Ford 640

R

Ramseyer35

New User
I have a ford 640 that I can't get to
start. I have spark and timing is as close
as I can get it. It will crank and act
like it wants to start but it blows gas
back out of the carburetor. I'm wondering
if there is a blockage somewhere in the
intake manifold. When I pull the plug on
the fuel bowl I get gas out and if I spray
ether in it will almost start. Does anyone
have any ideas?
 
Ignition rotor moves around how much? Loose on the shaft or fairly snug?
Last worked on it did what? When?
 
The rotor is snug and there's minimal play on the shaft. The tractor hasn't run since probably 2005. I pulled the pistons and put new rings in. But when i pulled the spark plugs they didn't smell like gas which made me think there is a block somewhere in the intake manifold.
 
Pull the tube between the air cleaner and carb. Turn it on and hold your hand over the carb intake while you try to start it. You should get both a good suction on your hand and gas on your hand and it may even try to start
 
Almost start on ether tends to tell me the timing is whack.
Pull out #1 plug and bounce it over with your thumb over the plug hole.
When it starts to blow your thumb off the hole, stop cranking and look for the timing mark.
Tap it a few more times to get TDC on the comp stroke.
Pull the dist cap.
How far from the #1 lug inside the dist cap is the rotor pointed?
If it's a bit of a distance off, you might consider marking the position of the rotor aligned with a component on the engine or scribe a mark on the eng block.
Pull that dist and inspect the dist gear.
No problem found?
Stuff it back in the hole, aligning the marks up again. Yes, the dist rotor will twist a bit when you stuff it back in again.
Make sure the rotor is still in alignment with your block scribe when you stuff it.
Problem found?
Fix it and stuff it back in as per above.
 
Intake blockage is not likely, but exhaust blockage is!

Try loosening the exhaust pipe, see if it will start. Could be the muffler is clogged with rodent packings.

Could also be stuck open valves.
 
I knew a man that had the timed the engine using the wrong cylinder.
It's too early to remember the firing order of my Jubilee.
Instead of using #1 plug to set the timing, he used the cylinder that is at TCD the same time #1 cylinder is at TDC.
 


Do you really mean that the gas blows back or is it running out the intake after cranking? If it is the latter it is normal for any updraft carburetor when it doesn't start within five seconds of cranking.
 
We bought a Cub a couple weeks ago, carb was missing, manifold was full of dirt dauber nests .... It's a possibility. Have seen tail pipes packed full of all kinds of crap, too.
 
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