Ford 4000 can't advance timing enough with distributor

Hey all,

I've got what is definitely a timing issue, but other things may be going on as well. I recently tuned up the tractor - a 1972 Ford 4000 3-cyl gas - replacing the plugs and wires, distributor cap, points, rotor, etc. I thoroughly cleaned the distributor and lubed it as needed; all the parts seemed to be working fine (weights, advance, camshaft, etc.). But I can't get it to the right timing. It seems like I can only place the distributor gear shaft all the way down in three very distinct spots, and even rotating the distributor all the way too the left (most advanced) until it bumps into the carb, I'm still way off time, with an idle of 200-300 rpm (desired 600-700). I'm just seeing the part numbers on the flywheel through the inspection hole, not the degree marks that I want. Also, higher rpms result in rough running, seeming like it occasionally misses a spark or something. I've taken the distributor out and put it back in a few dozen times and am at wits end. Any thoughts? Any way to advance the timing independently of the distributor but get it to be in a spot where I can actually fine-tune things by rotating it? Many thanks in advance
 
If you cannot rotate the distributor sufficiently to obtain proper ignition timing, the distributor is not installed to engage the correct gear tooth, and, probably, the spark plug wires are not in the correct cap towers.

Dean
 

I got the distributor into place on the right gear tooth and adjusted the timing. Now one new issue : I can set the timing and run it just great for a little bit but if I come back a day later it runs like crap and the timing is way off (usually retarded beyond tdc). Any thoughts on what might be causing that?
 

First off, check dist shaft for excessive play,, which will make the timing all over the place. if shaft can be wiggled,, the bearings are bad, and it will not time correctly and will be erratic.

Check for missing or worn lobes. (very rare)

then check the centrifugal weights and springs. if they are binding or missing, the dist will be stuck in various advanced modes and move all over the place.

Then check the vacuum advance to make sure it returns correct with the spring load in the diaphragm. It should always return to base timing and not hang up.


Then check dist shaft bottom, and the opposing oil shaft for wear or problems. Shaft must engage and not be loose or slip. if rounded corners, it could slip.

Check points and mounting plate, for tight fit, no slipping and the points mounting plate should be firmly anchored on its pivot. screw holes not stripped out..

Distributor cap tight, no carbon tracks or cracks on the bottom side, No moisture for spark to jump. rotor good and not worn out fit tight on top of shaft, not wiggle around,,, in lots of cases the little metal adaptor under the rotor will be missing and allow it to wiggle around.

check for missing ground wire on points plate.

Check plug wires for good brass ends and good contacts, no cracking or falling apart.

This should get you stable correct timing. Timing must be stable.

using a timing light the timing should be very stable on the flywheel and not moving much at all. a dwell meter will also tell if the points gap is stable and the dwell should be rock on and not vary. A varying dwell will point to most of the above and must be corrected.

After all of this,, then concentrate on the correct dist timing and or plug wire placement. I have even moved all the wires over a hole to keep from pulling the distributor and put it back in the center of the adjustment range, but you really should not have to do this if everything is correct and your have put the distributor back correctly.
 
Thanks so much for this thorough checklist - very helpful. However, I went through every point and none of those issues is present. I even borrowed another distributor from a friend from a working Ford 3000 and same problem. This project has been a total mystery to myself and a friend who is a retired mechanic. I've gotten it to run great, then it sits for a couple days, runs like crap, sits for a couple days, doesn't even start. Timing seems good after a good run (check with timing light), then on next startup is WAY off. The real question is what happens while it sits/starts/turns off that could affect the timing.

Currently it's in a no-start state. Engine turns over with starter, just puffs thin white smoke out the exhaust (I've been here a few times before already on this project). I checked all the plugs and wires for good spark, timing lined up, firing order right (never assume) and nothing except a very occasional huge backfire. Guess I poke around in the carb next, but I'm at wits end with this thing!
 

just guessing... but first off china points that coorode and need cleaning after sitting a couple of days are a huge problem..

but... check the points gap each time.. they must stay set or you have a mechanical problem...are they set at 22 or what every the gap is for your tractor?

put a mark on the plate and the side housing to show when the timing has returned from advanced time to static base timing... each time you check the tractor, did the base plate return to static base timing? or did the advance hang up?

Point being.. if all of this is checking out and distribitor is true,, then your timing slipping has to come from underneath...

distribitor runs off of oil pump shaft,, examine both ends with a flashlight to see if the are worn and slipping...

oil shaft runs off of cam gear... that shaft may have a pin holding the gear in place and it could be slipping.. so you may have to pull the oil pump and replace.. but I would make damn sure before I went to the trouble to do that.


cam is run off a gear in the front of engine and if that gear slips it will never run right if run at all...
 
(quoted from post at 10:03:37 05/24/16)
just guessing... but first off china points that coorode and need cleaning after sitting a couple of days are a huge problem..

but... check the points gap each time.. they must stay set or you have a mechanical problem...are they set at 22 or what every the gap is for your tractor?

put a mark on the plate and the side housing to show when the timing has returned from advanced time to static base timing... each time you check the tractor, did the base plate return to static base timing? or did the advance hang up?

Point being.. if all of this is checking out and distribitor is true,, then your timing slipping has to come from underneath...

distribitor runs off of oil pump shaft,, examine both ends with a flashlight to see if the are worn and slipping...

oil shaft runs off of cam gear... that shaft may have a pin holding the gear in place and it could be slipping.. so you may have to pull the oil pump and replace.. but I would make damn sure before I went to the trouble to do that.


cam is run off a gear in the front of engine and if that gear slips it will never run right if run at all...
distribitor runs off of oil pump shaft,,' Odd duck......usually the other way around, where gear is on distributor & distributor drives oil pump.
 
(quoted from post at 07:03:37 05/24/16)

distribitor runs off of oil pump shaft,, examine both ends with a flashlight to see if the are worn and slipping...

oil shaft runs off of cam gear... that shaft may have a pin holding the gear in place and it could be slipping.. so you may have to pull the oil pump and replace.. but I would make damn sure before I went to the trouble to do that.

I believe your thinking about a 4 cylinder engine. 3 cylinder engine distributor is driven by an accessary drive mounted to the front timing case that is driven by the timing gears.
Oil pump is driven by the cam on the other side of the engine.

I can't think of anything that would cause a timing issue as described. Have you used a timing light while cranking the engine to see if it is a timing issue or just not firing.

Due to China junk points and condensers, for years I have strongly recommended to friends they convert to electronic ignition.

Pertronix makes conversion kits for most all old tractors and we've had good results using these kits with the engine starting easier and running better than with the old point system.
 
The huge backfire means you don't have ignition, the air/fuel is passing thru the engine and into the exhaust manifold, where the odd cylinder that does fire sets off the rest in one big bang.

I could thumb the kill switch on my motorcycle for a couple of seconds rolling down the road, turn it back on and a 12 gauge going off.

All the points and condensers in my stuff is still US made, so the comments about the Asian junk going intermittent makes some sense. The US stuff never did that in my experience.

I don't see a mechanical issue like the distributor going in and out of time based on letting the engine sit for a day and then it's NFG. So look really hard at the points and point plate and advance mechanisms. Do you have gray hair? You need that to work on Kettering ignitions.
 
yes... I was dreaming about a yblock... when describing the system.. and yes,, the gear is on the dist shaft, not the oil drive...

got to wonder if the pin on the gear broke, and its slipping a bit.. but that is a LONG stretch.

I had one come in this week where the points screws were loose and the gap kept changing. cust swore it was the carb, but gap was all but closed. Also used wire nuts to twist ignition switch wires and had a high resistance resulting in almost no voltage to coil/points. If the customer is nice, I send em home with a hand shake.. If hes a jerk, he pays for the 5 minutes of work. His solid plug wires were driving my digital meter crazy with emf.
 
I started again from scratch (for the 3rd time), pulled out plug #1 to find tdc, set the timing for 2 degrees at idle, ran it for a good 30 minutes with lots of revving up and idling down. Initially had intermittent spark on cylinders 2 & 3 but think that was due to gas on them; cleared up after about 5 minutes. When I shut it off everything was in tip-top shape (just like the last couple times); we'll hope things hold.
 
So what was the ultimate solution for the distributer gear shaft
hitting the carb? Having the exact same issue with my 72' 3
cyl gas. Can't get the timing to advance enough without hitting
the carb. Thanks
 
To get it to not hit the carb, you have to find the right notch on the distributor gear to slip into the drive. This means finessing the distributor over just one tooth or two - just pull it up until you can just rotate it freely, scooch over a bit and put it back down. I found that there's really just one gear tooth where you have easy adjustments in both directions, especially if you have a big vacuum advance sticking off the distributor, which can block access to the clamp bolt for tightening it down.

End of my story though, just got a used distributor on Ebay and slipped that in. Had a mechanic friend look at the old one and neither of us could figure out what was wrong at all with it.
 

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