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Here we go again, Ford 8n

mikewood869

mikewood869

Well-known Member
After a valve job last year, the tractor is wanting another one. The 8n is starting to miss in either cylinder 2 or 3 I think. The plugs are new and gaped between .25 and .28 at the most with autos 216. You can hear the tractor miss. The tractor has good fuel flow and spark is good and the tractor burns a little rich with dark smoke when working hard. The tractor probably has between 25 - 50 hours from this year.
 
(quoted from post at 12:07:02 12/14/18) After a valve job last year, the tractor is wanting another one. The 8n is starting to miss in either cylinder 2 or 3 I think. The plugs are new and gaped between .25 and .28 at the most with autos 216. You can hear the tractor miss. The tractor has good fuel flow and spark is good and the tractor burns a little rich with dark smoke when working hard. The tractor probably has between 25 - 50 hours from this year.
Click to expand...
wants" a valve job? Well those old timers don't always want what they need. Has he checked with some sort of test to determine/verify that his valves are leaking? I expect that neither he nor his owner has. Running rich may be fouling a plug. Lean it out. Swap plugs from good cylinder into missing cylinder & see if miss moves with plug. Do a leak down & compression checks. Get some facts/measurements instead of relying on what he "wants".
 
Are you really meaning the plugs are each gapped at 1/4" or more?!?!? Or are you missing a ZERO.....
 
(quoted from post at 06:42:42 12/14/18) Are you really meaning the plugs are each gapped at 1/4" or more?!?!? Or are you missing a ZERO.....
Click to expand...

Sorry between .025 and .028.
 
(quoted from post at 05:55:44 12/14/18)
(quoted from post at 12:07:02 12/14/18) After a valve job last year, the tractor is wanting another one. The 8n is starting to miss in either cylinder 2 or 3 I think. The plugs are new and gaped between .25 and .28 at the most with autos 216. You can hear the tractor miss. The tractor has good fuel flow and spark is good and the tractor burns a little rich with dark smoke when working hard. The tractor probably has between 25 - 50 hours from this year.
Click to expand...
wants" a valve job? Well those old timers don't always want what they need. Has he checked with some sort of test to determine/verify that his valves are leaking? I expect that neither he nor his owner has. Running rich may be fouling a plug. Lean it out. Swap plugs from good cylinder into missing cylinder & see if miss moves with plug. Do a leak down & compression checks. Get some facts/measurements instead of relying on what he "wants".
Click to expand...
ast winter we did the valves a because the tractor ran like crap. It didn't even move, so we redid the valves to what the book said and adjusted the distributor because someone adjusted the crap out of it (the tractor didn't even run). The tractor ran great until last week when it started to miss. One of the plugs were wet, one was dry, one had dry carbon and I think one was clean (I don't remember the order of those). I've just noticed that the tractor is starting to loose power like last year, to the point where the tractor didn't even want to make it up a hill. I've been looking for the compression tester. I pulled the spark plug wire and it sounded like either cylinder 2 or 3. Could be a head gasket for all I know. We mostly use the tractor for light-ish work (dragging wood, pulling a small wagon and for what ever reason the golf cart.
Sorry if I'm all over the place.
 

I have two 8ns and one I have had for about 15 years, valves have not been touched. The other one I overhaul the engine 8 years ago and did the valves and seat at that time. Has not been touched since. They both run great, you are missing something. don't assume anything, find out for sure, do a compression check at least, Run it in the dark and look at the dist and wiring, you may see a light show.
Good luck
 
8N's have very weak valve springs. They work well as long as the valve stems don't get gummed up. Modern fuel has little or no detergent and it's not uncommon to have sticky valves. I battled this problem on my 8N until I went to non-ethanol gas and added Marvel Mystery Oil to the fuel. Since then, no more sticking valves.
 
(quoted from post at 07:53:40 12/14/18)
I have two 8ns and one I have had for about 15 years, valves have not been touched. The other one I overhaul the engine 8 years ago and did the valves and seat at that time. Has not been touched since. They both run great, you are missing something. don't assume anything, find out for sure, do a compression check at least, Run it in the dark and look at the dist and wiring, you may see a light show.
Good luck
Click to expand...
Going to try that and I’ll get back
 
(quoted from post at 08:18:23 12/14/18) 8N's have very weak valve springs. They work well as long as the valve stems don't get gummed up. Modern fuel has little or no detergent and it's not uncommon to have sticky valves. I battled this problem on my 8N until I went to non-ethanol gas and added Marvel Mystery Oil to the fuel. Since then, no more sticking valves.
Click to expand...
The tank is almost empty. I’ll add 5 gallons of fuel and add mmo to it and run it for a bit. Should have a bottle around somewhere
 
(quoted from post at 15:43:46 12/14/18)
The tank is almost empty.
Click to expand...

does this low power thing only happen when the tank is almost empty? the reserve pickup has been known to plug up. yours could be starting to do so.

after two sediment bowl assemblies did it to me, i gave up. i didn't want to replace the tank to eliminate the source of rust, so i left the inline filter in place that a PO had installed, and i never open the fuel shutoff valve past 2 full turns. tractor runs great, and if it gets down to ~ an inch of gas left, it just quits. if that happens, i pour more gas in and off i go.
 
If this is a Front Mount, pull the coil/distributor and be sure the point gap is proper on all four lobes of the cam... worn shaft bushings can translate to erratic behavior. Do the simple stuff first and good luck! :) (Side mounts need proper point spacing (gap) too!!!)
 
(quoted from post at 15:18:23 12/14/18) 8N's have very weak valve springs. They work well as long as the valve stems don't get gummed up. Modern fuel has little or no detergent and it's not uncommon to have sticky valves. I battled this problem on my 8N until I went to non-ethanol gas and added Marvel Mystery Oil to the fuel. Since then, no more sticking valves.
Click to expand...

I don't think sticky valves in the flathead is something new caused by lack of detergents in modern gasolines. I believe Mobil was one of the first to bring gasoline with detergents to the market in 1968 - prior to that gasoline had none. In 1995 a minimum level of detergents was mandated by law (EPA). Since 1995 all pump gasoline sold in the USA must contain a minimum level of detergents.

Subsequently tincreasingly stringent air quality standards and the nearly universal use of fuel injection and in particular Gasoline Direct Injection (GDI) engines has made higher detergency even more important. In 2004 a consortium of auto manufacturers decided the EPA minimum was too low and created the voluntary Top Tier Gasoline standard which mandates among other things detergent levels significantly higher than the EPA minimum. BP, Conoco, Chevron, Exxon, Shell and Costco products are all certified Top Tier products.

TOH
 
Have you checked your breaker points and spark advance? Carb settings? I would suspect those items, in that order, before going on to something like valves. After checking those items, I would move on to check compression/leakdown.

Colin
 
(quoted from post at 11:16:28 12/14/18)
(quoted from post at 05:55:44 12/14/18)
(quoted from post at 12:07:02 12/14/18) After a valve job last year, the tractor is wanting another one. The 8n is starting to miss in either cylinder 2 or 3 I think. The plugs are new and gaped between .25 and .28 at the most with autos 216. You can hear the tractor miss. The tractor has good fuel flow and spark is good and the tractor burns a little rich with dark smoke when working hard. The tractor probably has between 25 - 50 hours from this year.
Click to expand...
wants" a valve job? Well those old timers don't always want what they need. Has he checked with some sort of test to determine/verify that his valves are leaking? I expect that neither he nor his owner has. Running rich may be fouling a plug. Lean it out. Swap plugs from good cylinder into missing cylinder & see if miss moves with plug. Do a leak down & compression checks. Get some facts/measurements instead of relying on what he "wants".
Click to expand...
ast winter we did the valves a because the tractor ran like crap. It didn't even move, so we redid the valves to what the book said and adjusted the distributor because someone adjusted the crap out of it (the tractor didn't even run). The tractor ran great until last week when it started to miss. One of the plugs were wet, one was dry, one had dry carbon and I think one was clean (I don't remember the order of those). I've just noticed that the tractor is starting to loose power like last year, to the point where the tractor didn't even want to make it up a hill. I've been looking for the compression tester. I pulled the spark plug wire and it sounded like either cylinder 2 or 3. Could be a head gasket for all I know. We mostly use the tractor for light-ish work (dragging wood, pulling a small wagon and for what ever reason the golf cart.
Sorry if I'm all over the place.
Click to expand...

You say you did a "valve job" do you mean you removed the head, removed all of the valves ground the seats and the valves and lapped them in? Or did you do a valve adjustment to what the book said?
 
(quoted from post at 17:03:05 12/14/18)
(quoted from post at 11:16:28 12/14/18)
(quoted from post at 05:55:44 12/14/18)
(quoted from post at 12:07:02 12/14/18) After a valve job last year, the tractor is wanting another one. The 8n is starting to miss in either cylinder 2 or 3 I think. The plugs are new and gaped between .25 and .28 at the most with autos 216. You can hear the tractor miss. The tractor has good fuel flow and spark is good and the tractor burns a little rich with dark smoke when working hard. The tractor probably has between 25 - 50 hours from this year.
Click to expand...
wants" a valve job? Well those old timers don't always want what they need. Has he checked with some sort of test to determine/verify that his valves are leaking? I expect that neither he nor his owner has. Running rich may be fouling a plug. Lean it out. Swap plugs from good cylinder into missing cylinder & see if miss moves with plug. Do a leak down & compression checks. Get some facts/measurements instead of relying on what he "wants".
Click to expand...
ast winter we did the valves a because the tractor ran like crap. It didn't even move, so we redid the valves to what the book said and adjusted the distributor because someone adjusted the crap out of it (the tractor didn't even run). The tractor ran great until last week when it started to miss. One of the plugs were wet, one was dry, one had dry carbon and I think one was clean (I don't remember the order of those). I've just noticed that the tractor is starting to loose power like last year, to the point where the tractor didn't even want to make it up a hill. I've been looking for the compression tester. I pulled the spark plug wire and it sounded like either cylinder 2 or 3. Could be a head gasket for all I know. We mostly use the tractor for light-ish work (dragging wood, pulling a small wagon and for what ever reason the golf cart.
Sorry if I'm all over the place.
Click to expand...

You say you did a "valve job" do you mean you removed the head, removed all of the valves ground the seats and the valves and lapped them in? Or did you do a valve adjustment to what the book said?
Click to expand...
We did everything. The tractor is a 1950. I got sidetracked so I didn’t get a chance to look at it again
 
hmmmm,old style fuel used lead as a valve lubricant,newish fuel is unleaded.try a lead additive to your fuel=no more sticky valves.just a guess.
 
There is NO lead in lead additives they are a JOKE and a waste of money.ATF or Marvel Mystery Oil In the gas is the answer.
 
Sorry, LEAD has been outlawed in the USA for years. There is no such thing as a 'lead additive'. Maybe a few unscrupulous snake-oil products but either way you do not need lead in these low compression engines anyway -old wives tale.

Tim Daley(MI)
 

they are lead substitutes, not lead additive. i suspect that if u were to check the labels, u would see that none of them claim to contain lead.

are the people who make it any more "unscrupulous" than the makers of MMO?
 
I check for spark and the tractor has spark. I added 5 gallons of fuel and that didn't make a difference with the mmo (I know that takes time to get through). We have electronic ignition installed in the tractor. The tractor also has a new fuel tank because the old one started to leak around the fuel bowl. This low power started up started up around Dec 17th 2018.

I don't know if you can hear it misfiring but:
Running at half throttle
https://www.youtube.com/watch?v=TiXUAG1nOzg

Running at idle throttle:
https://www.youtube.com/watch?v=rgtfaXckj0M
 
Did a compression test with the spark plugs out and the readings are; cylinder # 4: 110, cylinder # 3: 110, cylinder # 2: between 95 and 110 and cylinder # 1: 110.
 
The compression test says I have over 90 in each cylinder. I also re-gaped the spark plugs to .025. Did the test as the tractor was a little warm. The tractor still misses. I'll be pulling out wood with the tractor today to get some fuel with mmo in it. Can I add mmo to the engine oil to see if the mmo works?
 
Went through a tank of fuel and it ran out of fuel yesterday (took a little over 6 hours). I filled up the tractors tank yesterday with gas and dumped a quart of mmo into the motor today, with four ounces of mmo for every 10 gallons. On the bottle said to dump a quart and half into the motor (20 % whats in the motor which has 6 quarts in the motor). Would this be too much mmo for a 8n motor? Either than that the tractor hasn't been used that much lately. Just to feed the cows in the rain. Should be pulling brush/ trees tomorrow if it doesn't rain.
 
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