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Subject: 8N Performance degrades when warmed up

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Rick    Posted 04-21-2017 at 09:15:26 [URL] [DELETE]        [Reply] [Email]  
  • 8N Performance degrades when warmed up
  • I just installed a Pertronix electronic ignition (still 6 volt though) and it started right up and idled great and ran smooth when revved up. The best it has run in years. I was mowing uphill in 3rd gear if you can believe that. Then as it got up to temp the performance began to degrade some. What's odd is that it was fluctuating from terrible to not so bad and back again. When going uphill with PTO engaged I would have to downshift to 2nd or 1st but it would still go uphill in reverse, which I'm not mistaken is a higher gear than 2nd? Nyway, pun intended, I was still able to finish mowing the field I was working on, it didn't seem to run as smooth as when cold, sounded like it was starving for gas here and there then would clear up and missing or sputtering to a minor extent. I just replaced the plug wires at the same time so maybe one of the crimped fittings is not a great connection. The timing is also another possibility, but why would it run good when first started and then not so good when hot? So how do you adjust timing when running? You'd have to be crazy to reach in there and adjust the distributor (front mounted)while running. So what do you do, shut it off and trial and error the timing? Any Idea's on this would be appreciated.

    Rick    Posted 05-14-2017 at 07:56:42 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • Here is the update on what I discovered. After all the suggestions I started with draining the gas tank and checking the fuel path from point A to the carb. I did find a very small piece of debris in the top of the float bowl assembly. It made a small difference when I compared the fuel flow before and after I removed it from the fuel line before it attached to the carb. The big difference was coming out of the bottom of the carb when I removed the plug. The flow was noticeably slower. I knew when I put the after market carb on that the linkage did not give me full throttle with this carb. If I manually pulled on the linkage I would get an extra 15% or so of power so as I stated before I ordered a rebuild kit for the original carb. Do not buy the kit from e-bay that comes from India, at least 5 of the threads on the different parts did not fit. Fortunately when I broke it down it didn't need a thing, I cleaned and checked it but it was good to go. When I installed it back on the tractor it ran great as before but when it warmed up it never degraded. So problem solved and I would have to conclude that the problem was related to fuel flow through the aftermarket carb. It doesn't make sense to me that it ran great before it warmed up, the fuel flow should have affected it no matter the temp of the engine. But the results don't lead to any other conclusion. Thanks everyone who contributed with suggestions.

    Jock(OR)    Posted 04-22-2017 at 00:02:18 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Performance degrades when warmed up
  • You say it is a 1952 8N, so it should have a side-mount distributor with a regular cap like a car and a remote mount coil. Is this correct?

    If it has a side mount distributor, does it have a timing hole with a cover plate on the right side of the bell housing just behind the exhaust pipe? If yes, then there should be timing marks on the flywheel that you can see through the timing hole.

    Timing a side mount is very different from a front mount, and requires a timing light.

    Rick    Posted 04-22-2017 at 07:26:41 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • It has a front mount distributor. I just state what I have been told so maybe it is a different model year.

    Tim Daley(MI)    Posted 04-21-2017 at 17:03:26 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Performance degrades when warmed up
  • First, like Bruce(VA) said, you don't time the distributor on the tractor while it's running. Do you have ANY of the essential manuals -F04, MPC, Operator's? Timing is set with distributor on the workbench as show below -SEE LINK. Next, sputtering or dying? Any change with PTO disengaged? Define 'performance' better. To me I'd bet it is a fuel issue. With COLD engine, loosen the fuel line at the brass carb inlet, move the line up and out and pointed down into a coffee can or gas can. Open the sediment valve 2 FULL TURNS. Observe fuel flows, pencil thick stream nice and steady, uninterrupted. If it sputters, stops and starts, there's your problem. Sediment bowl screens most likely clogged. Search archives on that topic. My next idea is to check wiring. If 'sputtering' means cutting in and out, you may have a short in the wiring. Another test would be to revert back to the original electrical system, get rid of the Pertronix (for now) just to do a process of elimination. You don't say how the tractor was running BEFORE you installed it nor why you installed it. Oftentimes fellas have other issues and think just a 12 volt conversion or an EI conversion will fix the problems, but usually cause more. Backfiring/sputtering/missing can be due to a short. You say runs the best it has in years, so if you don't have the manuals by now, shame on you. ALL mentioned have parts breakdowns and diagrams of the distributor with the OP and the F-04 having in-depth R&R procedures...

    Tim Daley(MI)

    Rick    Posted 04-21-2017 at 22:37:34 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • Wow, where do I begin after that, I feel like I just got scolded by my father. First let me start by saying I know you don't adjust the timing on an 8N while it is running, I was really just venting about working on an antique. I've seen what the manuals show about setting the timing, which is laughable to think they go into such detail to show "the" correct position, like a 52 8N is so precise, the mere fact that the timing is changeable nearly screams that one specific position cannot be correct for the million 8N's out there, if it was it would not be adjustable. Remember this is a 1952 8N, not a 2016 Pagani Huayra. With a V8 you would set the timing while running, with a timing light, and if you didn't have one you could set it by ear. Also remember this no longer has points and a condenser, it is electronic so is the timing going to be set in the exact same spot? The Pertonix installation directions say to set the timing adjuster, there's that word again, in the middle position but I think you are giving them too much credit if you think that means that is where it is supposed to stay. I think they just wright lousy directions and assume you know to adjust the timing after you get it started. Could I be wrong? Maybe, but I don't think so. Moving on, it sputters but just barely, it doesn't die. It might if I continue to push it when it starts getting weak up hill but I don't push it. Let me jump to the end right here and and say that I don't own the tractor. It belongs to a 90 year old widow who I try to help in any way I can. I have been hunting this property for 30 years and recently lost one friend to a move to another state and one to an early death. I'm all that's left to keep the place from getting taken over by the autumn olive so when I take her there for a visit with some other friends it still looks half way decent. The tractor has been worked on and tinkered with by many people over the years. It has just been the last several years that my friends who are now gone and I have been trying to keep it in a usable state. Now that it is just me I installed the electronic ignition and changed the plugs and wires to try and get it to start without a jump which it hasn't been able to do for over a year. I don't think the plug wires have been changed in decades. O.K. I'm venting again so I'll end it after I say I appreciate your suggestions. I came here because I needed input from people with experience. I will check out the fuel line from float bowl to carb, which I replaced with a cheap after market carb last year. I have a rebuild kit on the way to get the original back on the tractor in the near future. Again, I appreciate all the help I can get here, I would just appreciate it a little more without the self righteous attitude.

    K.LaRue-VA    Posted 04-22-2017 at 09:34:25 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • In Fact, with a front mount distributor, when we set the point gap and timing, that distributor is right for any of the thousands of front distributor tractor engines. In the past, I attempted to "tweak" the timing by moving that slider a bit, and always ended up putting it back where it was. With the Pertronics module, there is no point gap to set, so they built the device to be timed correctly at the midpoint of adjustment. Set it and forget it. Look elsewhere for problems such as loose wires, bad ignition switch, ignition resistor, dirty wire terminal connections, fuel flow.

    Tim Daley(MI)    Posted 04-22-2017 at 09:01:30 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Performance degrades when warmed up
  • Rick-

    Not scolding nor berating you nor portraying a self-righteousness. We're trying to help. Let's back up a few steps and first determine what it is you have and are dealing with. It's not a '52 if it has a front mount distributor. Do you still have the original M/S carb? If so we can help get it rebuilt good as new -cheap Cheena made ones usually are junk these days. It now sounds like several people have 'worked' on this so who knows what has been done to it. I don't think it is a timing issue and the method set forth for over a half million other N's seems to work fine. I simply suggested you remove the Pertronix, at least for time being, and go back to the OEM distributor, start there, get the fuel/carb issues resolved, wiring/charging next, and work forward from there.


    Rick    Posted 04-22-2017 at 13:42:04 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • I'm going start with the easy possibilities first and see if it comes around. I just don't have the time to start breaking this thing down any further than I have to. If it was parked behind my house instead of 50 some miles away I might be more inclined at least at some point to check every part mentioned. Right now it starts and runs light years better than it was so I can use it and trouble shoot when it is raining and have a little extra time. I'm going to start with the fuel line then move on to some electrical parts. The governor is also something I might fiddle with a tad to see if it may be part of the problem.Who knows what time of year it will be by the time I get past this starting list. If I even need to. If I can get it purring like a happy cat I might switch modes from problem solving to the more important maintenance issues. An ounce of prevention as Ben used to say.

    Ed Gooding (VA)    Posted 04-22-2017 at 09:15:47 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • Not scolding? How do you think a comment like this would be interpreted, Tim?

    "... so if you don't have the manuals by now, shame on you...."

    Despite your stated good intentions, your reply was condescending as hell and as an Admin here, you should know that we do not treat our guests in that manner. That's left to Dell over on YT - we do not want that type of culture here.

    Jim    Posted 04-22-2017 at 11:15:09 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • I personally thought Tim's comment was just a light jab but without malice and as a newbie would not have offended me.

    Rustyal    Posted 04-21-2017 at 15:35:07 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Performance degrades when warmed up
  • I would suggest the tractor could be overheating. And it is possible the time is off to to wear in the distributor cam shaft drive slot. Also the distributor drive tang. My coils are mounted to the engine with no problem. Also, try not to cut uphill in 3rd. Good luck.

    steveVa    Posted 04-21-2017 at 15:31:12 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Performance degrades when warmed up
  • Could be the fuel flow to your carb. Does it run ok if you idle down when it gets hot?

    Rick    Posted 04-21-2017 at 15:48:48 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • It does seem to idle ok but there really isn't any load on it at idle and since it still runs even though degraded, when idled down I'm not sure that is a good indication of a problem. Also, I would think if the fuel filter is clogged it would be clogged cold and hot. But, I'm not going to completely rule it out just yet, but it doesn't logically raise a red flag to me. But again, over the past 35+ years in the plumbing trade just because it doesn't make sense doesn't mean it can't or won't do it anyway. So, I will add it to the list to look into further and report back later. Thanks for the idea, Rick

    steveVa    Posted 04-21-2017 at 16:01:21 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Performance degrades when warmed up
  • It is not unusual for the flow to get restricted to a trickle so it runs fine until the rpms get up there. Easy to check. Pull the plug in bottom of carb and see how fast it fills a small jar. Flow should be good and steady and not slow down to a trickle.

    Rutyal    Posted 04-21-2017 at 16:27:48 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Performance degrades when warmed up
  • And it can be clogged in the bowl just like a plumber.

    Rick    Posted 04-21-2017 at 22:39:58 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • I guarantee if the bowl is clogged, I will get it open :)

    Corvette8n    Posted 04-21-2017 at 12:50:34 [URL] [DELETE]        [Reply] [No Email]  
  • Re: 8N Performance degrades when warmed up
  • I'm not familiar with the pertronics, but does it use a condenser? If so try a new not nos one, also the coil can get hot, may need to be replaced.

    Rick    Posted 04-21-2017 at 14:24:02 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • No condenser and the coil is new with the Pertronix kit, 40,000 volt flamethrower. But, the coil is mounted to the engine so it probably gets hot. Do you think that could be a problem? If temperature would be an issue shouldn't they have mentioned that in the installation instructions? The instructions were horrible but the process is not that complicated so I didn't have any issues but I suppose it is possible they could have forgotten to mention something like that.

    Ozlander    Posted 04-22-2017 at 12:31:01 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • Almost all coils are mounted to the engine.
    I don't think that is the problem.

    HCooke    Posted 04-21-2017 at 11:49:30 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • Rule out a failing ignition switches by jumping around it. Switch gets corroded and the resistance increases when it warms up. I doubt it is your timing.

    Rick    Posted 04-21-2017 at 14:27:27 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • That is simple enough to try, I'll let you know how it goes.

    Bruce (VA)    Posted 04-21-2017 at 09:49:45 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • Adjust timing when running? No, that's not how it's done. The distributor needs to be off the tractor to adjust the timing.

    But don't worry about it because now that you have EI, you can't realistically adjustthe timing anyway. Pertronix gets away from telling you that by just saying to center the plate.

    EI will indeed address minor bushing wear, but it will not fix it. Nor will it fix sticky or broken advance weights.

    Pull the distributor. Check the bushings and advance weights.

    Rick    Posted 04-21-2017 at 10:19:02 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • So moving the timing bar, that Pertonix says to put in the middle during installation, has no effect on timing when moved? It still changes the relation/physical location of the sensor in relation to the magnet doesn't it? Wouldn't this change the timing of the spark? I have not read up on the bushings or the advance weights but I did not notice any play in the rotating mechanism when I had it apart. I however did not inspect the advance weights, should it operate easily with hand pressure? What else should I look for? And if it does not operate freely, do i just take it apart and clean and grease? Or replace? Thanks Bruce, I am also in Virginia. I live in Annandale but the tractor lives in Viewtown now known as Amissville about 15 minutes from Warrenton.

    HCooke    Posted 04-22-2017 at 09:08:10 [URL] [DELETE]        [Reply] [Email]  
  • Re: 8N Performance degrades when warmed up
  • "So moving the timing bar, that Pertonix says to put in the middle during installation, has no effect on timing when moved?"

    It will have an effect. But there is no way to time it with the Pertronix module so that it is why they recommend leaving in the middle. Several things to check - the gas tanks on these tractors are vented. That vent hole can become clogged and gas flow is restricted. Opening the gas cap when it has running issues will help diagnosis this. Also jump around the ignition switch as I suggested. Also check for fuel flow THRU the carburetor as suggested above.

    After rereading as of the above posts, I suspect a fuel flow problem to be more likely than a timing issue.

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