Front distributor advance weights

[Dogdoc427]

Hello all,

I have a 9N that has been in my family for close to 60 years, my uncle is the second owner, the first was the owner of what was our local Ford Tractor dealership. It has always run strong and been as reliable as any of the old iron. The past few years it has not been used much, he has some newer machines. He gave it to me so it could be used and kept alive. Problem - it is not running well right now. At first it had to be roll started, we tuned it up (new points, plugs, wires, condenser, cap, rotor, 12V coil, checked bushings and static timing, both good). Now it starts but still starts a bit hard. Once it starts it backfires on acceleration / deceleration and doesn't have much power. Checked the sediment bowl, inlet screen in the carb and freshened the gasoline. It had a new carb a year or 2 ago, checked float height and all is good. It SOUNDS to me like a timing issue. How do I know if the advance springs are still any good? The weights are free and flop a little when the distributor is on the bench. I've never had a new cam and weight assembly in my hand so I have no reference for tight or loose as far as spring tension. Any help? It has been short blocked twice and to my knowledge this is the original distributor (not sure of the year).

 

[Greg (2N) TX]

Weights should return to collapsed position toward
the center. New springs will ensure that given there
is no binding.
FO-4 manual is always your friend.
Greg

 

[ratface]

yep, they return via the slots available for travel without any forcing. A bad one will bind up and not move much if rusted.

 

[JMOR]

I would be looking at fuel mixture problems, as I have never known occasional backfiring, especially as related to advance mechanism, to be a timing issue.

 

[Dogdoc427]

Thanks Greg.

They are free, not binding up but if you hold the shaft horizontally (as it would be in the tractor) the bottom weight falls away from the shaft about a 1/16th, maybe a bit more. I know they are fussy about correct timing to start easily and figured if the springs are weak the timing might be going to full advance before everything else was ready.

 

[Dogdoc427]

JMOR,

The instructions I read for tuning the carb are pretty straight forward. Basically with it running turn the idle mixture screw in until the engine stumbles then back it out a half turn then set idle speed to 400 rpm. Next bring it to full throttle and do the same thing with the Hi idle mixture screw. I did that and more, 1/4 turn more or less and different combinations of screw settings, the one constant is the backfiring which is what leads me to think there is a timing issue. I wondered if there is a spec or "pass/fail" criteria for spring tension on the weights.

 

[Dogdoc427]

Rat,

Thanks for the response, the slots are clean and free, see my other responses. I'll get into the manual on here and see what I can find

 

[JMOR]

(quoted from post at 07:30:34 08/01/16)
JMOR,

The instructions I read for tuning the carb are pretty straight forward. Basically with it running turn the idle mixture screw in until the engine stumbles then back it out a half turn then set idle speed to 400 rpm. Next bring it to full throttle and do the same thing with the Hi idle mixture screw. I did that and more, 1/4 turn more or less and different combinations of screw settings, the one constant is the backfiring which is what leads me to think there is a timing issue. I wondered if there is a spec or "pass/fail" criteria for spring tension on the weights.

o ease your timing concerns, let me say that you can lock the centrifugal advance to full advance (weights all the way out) and set static timing such that it will start & run fine. Likewise, you can lock those weights 'in' where they can never sling outward & set the static timing such that it will start & run just fine.Neither will result in the intermittent misfire under certain conditions that you describe. There are valid reasons for centrifugal advance, but that is not of concern here. Remember, that the advance is full 'in' at a speed not much above idle.

 

[R Geiger]

I would do a compression test, you may have sticky valves. One can guess all he wants and sooner or later you will find the problem or one can do a bit of troubleshooting to locate the problem. Do the cheap things first.

 

[Dogdoc427]

JMOR,

I won't argue that IF (not likin' that word) you made the appropriate adjustments it may act as you describe. I'm faced with a tractor that I have known since the age of 8 (I'm 53 now) to run well and start well. It doesn't do that now. When I got it from my uncle I had no idea when it was last tuned up or when it had it's last oil change so I decided to start there and create a set of "knowns" or givens, just a place to begin.

 

[Dogdoc427]

R Geiger,

:? I waited to respond because at first I was a little insulted by your response. When I thought about it we do not know each other and I have not gone deep into detail so I'll start with some background and get to the details. I've been a professional mechanic / technician for over 30 years (40 if you count my teens, tinkering with this tractor, mini bikes, motor cycles, lawn mowers, field cars, bulldozers and much more). I was an ASE Certified Master Heavy Truck Tech, L1 and L2 electronic diagnostic certs, Mack Master Tech, Cummins cert, Eaton Cert, Shepard cert just to start. I've worked the last 15 years on highway construction and maintenance equipment and now as supervisor in the same garage where we repair plow trucks with all manor of electronics from modern diesels to the computerized material handling systems for sand and salt spreading. Let's just say I'm not new to diagnosing or troubleshooting. Good diagnostics start with not overlooking the obvious or taking anything for granted. My world has been almost exclusively diesel, a world in which [b:57a4b3d997]1[/b:57a4b3d997] degree off in timing on some engines can be the difference in an engine running well for a million miles or running poorly for only a thousand miles. These engines are not that fussy, I get that. My process started like this: I was given a tractor that no one can tell me the last time anything was done regarding maintenance. It didn't run right so I need to establish a base-line, I STARTED with fresh gas, cleaning the fuel bowl and screens and checking flow through the line. I was told a new carburetor had been installed 2 years ago and that after that occasionally fuel would run out of the carb intake so I wanted to verify float height was correct, needle valve was free and clean, and adjustments were right. Also proceeded with tuning it up replacing everything in the kit. While doing the tune-up I noticed the weights made some noise when the distributor was moved around. Didn't pay much attention thinking it might be normal. After some thought, on the ride to and from work, it occurred that the timing improperly advancing MIGHT be something to look into before going deeper. After the tune-up it still didn't run right, I now wanted to determine whether or not the advance weights are causing some or all of the problem. I came here to ask a simple question of those with more experience with these engines than I have; Is there a way to determine if the springs on the advance weights are bad? To my mind, if the static timing is set correctly and the springs on the advance weights fall away WITHOUT ANY centrifugal force THEN timing is advancing just from gravity acting on the weight before the engine is cranked and would cause a change in timing while cranking that could lead to hard starting....... I have read posts on this site to that effect. Diagnostically I would prefer to fix the problems that I KNOW exist before I dive deeper. The possibility that a valve or 2 is/are stuck exists and is not ignored. Once the new advance weight assembly is installed I will know what is NOT causing or adding to the problem. I am not guessing, I'm simply fixing the known and obvious before searching for the invisible.

So...... I don't think you intended to insult me, you probably wouldn't last long here if you were like that. I'm over it until someone gives me a reason not to be. I asked to be here and I am allowed on this site as long as I play nicely with others and within the rules, and I will. To you, sir I thank you for your reply and input, have a great day.