Ford 3000 runs rough

[davka]

My Ford 3000, 1966 model, gas, 3 cylinder was running rough. I put in new autolite plugs, new plug wires, new rotor, condenser and points. It is worse now, especially with open throttle. The bottom plate of the Holley Carb has been 'spitting' and it even spit out the gasket that was between the bottom plate and the carb. I reinstalled the gasket and it spit it out again. I attached a photo of the Holley Carb. On the photo, arrow #1 indicates the bottom plate (now without the gasket). Arrow #2 shows the broken gasket as it hangs below the carb.

Any suggestions on how to fix this problem? This was my first time doing a tune up but I think I got the gaps and everything right....but maybe not. The plug wires were difficult in making a secure connection on the plugs. Is the carb the most likely problem? I have a carb kit on the way. Thanks for any advice.

 

[davka]

I'm researching this and it might be described as a "backfire through the carb". That blows the bottom gasket out. What likely causes this?

 

[Roadworthy]

Have you considered adjusting the engine timing? It sounds as though it may be too far advanced. It's possible the advance is stuck. You may need to remove the point plate to check the flyweights for free movement or spring breakage. I think you're fixing the symptom without seeking out the problem.

 

[davka]

Have you considered adjusting the engine timing? It sounds as though it may be too far advanced. It's possible the advance is stuck. You may need to remove the point plate to check the flyweights for free movement or spring breakage. I think you're fixing the symptom without seeking out the problem.

Thanks for the reply. I will look at the engine timing next. Can you provide a little more info about how the advance might be stuck on a vacuum advance? My knowledge is limited but I believe the Ford 3000 is a vacuum advance. Flyweights and springs are in a centrifugal advance. Am I missing something? This area is really new to me.

 

[Roadworthy]

If you pull the point plate I believe you'll find flyweights in addition to the vacuum advance. If you have vacuum advance of course that could be stuck, too. Of course these things advance the timing if then engine is running so if timing is too advanced to start with they'd just make it worse. You could begin by static timing the engine - no timing light necessary for that. Check the dwell or the gap on your points. Be sure you check the gap when the cam in the distributor has the points maximum open. Are you certain the plug wires have it firing in the proper sequence? Firing order should be 1 - 2 - 3, the plugs should be gapped at about 0.025" and the point gap between 0.022" and 0.028" (TractorData.com Ford 3 tractor engine information)

 

[davka]

Thanks, Roadworthy. I will check everything you mentioned and, yes, the firing order is exact (1-2-3). I'll follow up. Thanks again.

 

[DJ54]

On my 2000 3 cyl., I had a similar problem about 15 years ago. If you look at a picture of the bowl gasket, you'll see multiple holes around the larger hole for the Venturi. I'm assuming from a previous backfire, before I got it, tore one side of that gasket loose, and pushed it back. I saw it as soon as I took it apart. I put it back in place, and sealed it with a small dab of #2 Permatex, just to see if it fixed the problem. I started it up, and it eliminated the problem. It's ran fine since then.

Since you already have the kit coming, be careful removing the bowl from the upper portion of the carb., to see it that one did the same. If it did, the new gasket in the kit should fix it.

 

[davka]

Re: Ford 3000 runs rough (backfire through the carb and spits out the lower gasket)

Hi all and thanks for the advice to date. Here is today's update: I checked the timing with a timing light. The timing process was not clear to me (saw different info in 2 manuals and couldn't really translate that to what I saw on the flywheel marks) but I did turn the distributor and saw a "2" on the flywheel; turned dist. and saw a "6"; turned dist. and saw a "10". None of the settings helped the engine at mid throttle idle. It still misses out. Please note that the engine runs very smoothly at LOW idle. Also, when I just touched the lever adjusting screw (it is on the carb left and behind the carb - see attached photo) it made the engine stumble and/or backfire. In summary, timing adjustments didn't seem to help in the engine performance at mid-idle.

Spark plug wires were double-checked and are in order (as 2 mechanics told me) (Firing order is 1-2-3 and number 1 from the distributor goes to the plug closest to the radiator). I plan to check the fuel filters, rotor for spring-back return, distributor flyweights, and possibly check the compression next.

Any ideas with this new info?

 

[lennyzx11]

Is the rotor pointing at number one plug wire with the #1 piston up at the top of the compression stroke?

Is the distributor turning a certain direction and the firing order is the same direction of rotation?
Distributor turning clockwise when cranked. Firing order set up clock wise also for your 1-2-3.

If you get a pop back through the carb “spitting “ than means a plug is firing with an intake valve open. This allows the explosion to travel back out the cylinder through the intake valve and out to the carb.

If you get a pop “backfire” out the exhaust pipe, the plug is firing when the exhaust valve is open. Allowing the explosion out through the exhaust valve and to the muffler/exhaust pipe.

Hope any of this helps.

 

[davka]

Thanks for the reply. I am new at this but I read everything I can on how to find TDC and I still can't find a precise way to do this. If you have guidelines I could sure use them and I will check the rotor. Question is: how do I get to or identify TDC. How would I determine which direction the distributor is turning? When looking at the engine with the hood open, the firing order printed on the engine is 1-2-3. However, I am told that #1 is nearest to the radiator. So #1 on the dist. is wired to the plug nearest to the radiator. Thanks again.