Ford 3000

I have 1972 Ford 3000 gas tractor that is giving me a fit.
This tractor has problem when you give it the throttle.
It misses and pops back into the intake.
It has new plugs, plug wires & the carb was rebuilt.
It has a electronic ignition conversion in the distributer.
If anyone has any ideas what the problem might be any and all information would be helpful.
Thank you Michael.

Just a couple of could-be's. Distributor timing or vacuum advance, carb accelerator pump, idle mixture.

Hey there Mike.
I toke the vacuum advance, no change.
We checked the timing twice and it is good.
The carb I had rebuilt by a shop that is repeatable, he even has a test motor that they run them on.

The 1 barrel Holley updraft
carburetor are well known be
problematic. I am guessing that is
what you're equipped with. They are
an aluminum or aluminum alloy
construction and wear over time.

Double check the plug wires and firing order.

Pull the valve cover and insure no push rods are bent, an exhaust valve not opening will pop back through the carb.
That Holley carb is very difficult to set up at best. Weak flow from the tank strainer is worth looking at.

All this checks out, put a Zenith carb on it. Yeah, I know you paid a carb shop good money. Can't polish manure.

It's that bloody holley.
When I get one I like to pretend I'm Tom
Brady and give it my very best heave into
the nearest swamp, dumpster or scrap
pile. Then I go buy the Zenith.
Zenith will make your tractor Run.

My 3500 did the exact same thing, and I did as many have mentioned. Tossed that blasted Holley carb, and bought a zenith from this site. Best thing I
could have done! Never an issue since, just purrs along now.

Typical causes of intake backfire:

Retarded ignition timing, be sure the centrifugal advance is free and working.

Weak spark, check the spark quality at the plug end of each wire. Caps and rotors, all ignition components are aftermarket, not always the exact match and questionable quality. Many times the timing between the rotor and cap terminals is off. Try to determine that the spark is happening when the rotor is aligned with the cap terminals.

Valve problems, an exhaust valve not fully opening will cause rhythmic popping back through the intake, increasing with throttle and load. Check the valve lash, visual inspection of all valve components. Have you run a compression test?

Lean mixture. Have you tried a partial choke to see if that gives improvement? If so it's too lean. Could be caused by lack of fuel to the carb. Disconnect the fuel line after the pump, direct the flow to a clean container, start the engine, let it idle. The pump should deliver a strong pulse of fuel with each stroke. Be sure to check the pump even if it is not suspect. Pumps do not like ethanol gas.

If good, reconnect to the carb, start the engine, at idle, remove the carb drain plug, catch the flow in a clean container. It should flow a good stream, not a drip or stop until the engine dies. Look at what was caught in both tests. If there is trash in the container, the tank is contaminated and so will be the carb.

I will agree with others, the Holley carbs were troublesome. Fought one for years, rare to have one defeat me, but that one did! The new Zenith made the tractor usable again.

Hope this helps, let us know...

Sounds like spark advance not working.

Do you have any so called friends like me
that think it's funny to switch the spark
plug wires around? Happened to me... TWICE!

Thank you everyone for the info.
We will get started on all these issues that it could be.
I will let you all know what the problem was if we find it.
Thank you everyone and have a great day.
Michael.