Carb help

[TSnyder]

I recently rebuild the motor / front end on a 1952 8n. This actually was my first ever rebuild project and it went fairly smoothly. The motor and paint are finished and i just fired it up for the first time since the rebuild a couple of night ago. Great oil pressure, etc etc and she purrs like a kitten as long as the choke is held out. I rebuild the carb prior to rebuilding the whole motor and it had this same problem before so i'm quite sure the carb is the culprit still, i have a feeling i just didn't get it cleaned enough or something. The tractor will idle at 300 - 400 rpm without the choke being held out but as soon as the rpms get up around 800 or more it starts to stumble and will stall, it even surges occasionally (governor was rebuilt with the rest of the motor). I have all the linkage on correctly and adjusted perfectly. My logic says that the tractor gets enough fuel when running at a low rpm so it doesn't cough or sputter but when it call for more fuel it can't get it so therefore restricting the airflow in (choking) it helps to balance it better. Also the feul flow to the carb is great, all screens / filters are clean and the fuel will flow out like crazy so i know thats not the problem. Also no matter how much i richen up the main mixture screw (screw out) it doesn't make a difference.

Any advice would be good. I kinda looks to me like i need to rebuild this one again and do a better job or buy a new one. Also the parts used in the rebuild were just a rebuild kit from Tractor Supply... cheap parts maybe.

thanks, Tyler

 

[JMOR]

(quoted from post at 08:38:30 06/02/11) I recently rebuild the motor / front end on a 1952 8n. This actually was my first ever rebuild project and it went fairly smoothly. The motor and paint are finished and i just fired it up for the first time since the rebuild a couple of night ago. Great oil pressure, etc etc and she purrs like a kitten as long as the choke is held out. I rebuild the carb prior to rebuilding the whole motor and it had this same problem before so i'm quite sure the carb is the culprit still, i have a feeling i just didn't get it cleaned enough or something. The tractor will idle at 300 - 400 rpm without the choke being held out but as soon as the rpms get up around 800 or more it starts to stumble and will stall, it even surges occasionally (governor was rebuilt with the rest of the motor). I have all the linkage on correctly and adjusted perfectly. My logic says that the tractor gets enough fuel when running at a low rpm so it doesn't cough or sputter but when it call for more fuel it can't get it so therefore restricting the airflow in (choking) it helps to balance it better. Also the feul flow to the carb is great, all screens / filters are clean and the fuel will flow out like crazy so i know thats not the problem. Also no matter how much i richen up the main mixture screw (screw out) it doesn't make a difference.

Any advice would be good. I kinda looks to me like i need to rebuild this one again and do a better job or buy a new one. Also the parts used in the rebuild were just a rebuild kit from Tractor Supply... cheap parts maybe.

thanks, Tyler

ou say you have good fuel flow.........I hope you mean good flow out the bowl drain plug & not just "to" the carb inlet.

If good through the carb & out the bowl drain, then look at this set of pictures/drawings & be sure every path is clear. (remove the * in the link below, when you copy/paste into address line of browser)
http://www.n*tractorcl*ub.com/howtos/pdfs/Cleaning-Carbs.pdf

 

[Jim in Western MI]

You've done a great job, but looks like an impasse. There's a resource here (GB in MT) that unquestionably can take care of this for you. I look forward to using him when I have to go to overhaul one day, but my 8N (whose little jets and screws haven't been touched in over 20 years) just purrs along at all speeds and loads. I've wanted to send my carb to him solely for the appearance of his finished product, but my ole' granddad taught me to quit fixin' things that won't broke. Jim

By the way, are you the Tim Snyder that used to go to Spring Hope in the Summer?

 

[TSnyder]

Wow, this is a great document. I'm quite certain if i take it back appart and use the phone line wire trick it should clear it out quite nicely.

In response to JMOR, i do have great feul flow through the drain plug in the bottom of the carb, not just to the inlet. The one noticably different thing about my carb though is that the standard sand plug (i believe thats what they call it, located beside the large bowl drain plug) is not original, it appears to have been farmerized and was replaced with a regular pan head screw. Could this be my issue? I have it screwed in tight so it wouldnt' be able to suck air from the hole but possibly it just doesn't fit quite right or the threads are tight enough. Another possibility is it may be to long and therefore is interfering with main power mixing area.

At any rate, does anyone know the correct size / type / thread of the sand plug or small drain screw in the bottom? I would say it wouldn't hurt to replace it... also, where to get one would be nice to know also unless someone happens to have an extra.

Thanks for the quick responses also, i can't wait to get this thing out for a joy ride this weekend (hopefully)!

P.S. Jim in Eastern NC... sorry to disapoint you, i'm Tyler Snyder from PA. Also, your advice passed down about not fixing things that arn't broke is actually great advice... wish i could listen some times! Honestly this bein my first rebuild of any kind and having it go so well and have so much fun, i'm pretty sure i have a new favorite hobby.

 

[JMOR]

(quoted from post at 09:27:52 06/02/11) Wow, this is a great document. I'm quite certain if i take it back appart and use the phone line wire trick it should clear it out quite nicely.

In response to JMOR, i do have great feul flow through the drain plug in the bottom of the carb, not just to the inlet. The one noticably different thing about my carb though is that the standard sand plug (i believe thats what they call it, located beside the large bowl drain plug) is not original, it appears to have been farmerized and was replaced with a regular pan head screw. Could this be my issue? I have it screwed in tight so it wouldnt' be able to suck air from the hole but possibly it just doesn't fit quite right or the threads are tight enough. Another possibility is it may be to long and therefore is interfering with main power mixing area.

At any rate, does anyone know the correct size / type / thread of the sand plug or small drain screw in the bottom? I would say it wouldn't hurt to replace it... also, where to get one would be nice to know also unless someone happens to have an extra.

Thanks for the quick responses also, i can't wait to get this thing out for a joy ride this weekend (hopefully)!

P.S. Jim in Eastern NC... sorry to disapoint you, i'm Tyler Snyder from PA. Also, your advice passed down about not fixing things that arn't broke is actually great advice... wish i could listen some times! Honestly this bein my first rebuild of any kind and having it go so well and have so much fun, i'm pretty sure i have a new favorite hobby.

hat is there for a liquid drain...in event of too much choking, malfunctioning float/needle/seat, etc. If all is well, it doesn't hurt to have it plugged, but the "filtered" drain is good insurance. Since tank is above engine, gravity could empty tank contents into carb, manifold, engine & crankcase diluted with several gallons of gasoline spells engine rebuild.

 

[Dell (WA)]

Tyler.......you ask......"does anyone know the correct size / type / thread of the sand plug".......ittza "sinstered bronze" filter made of tiny balls of bronze pressed together. Many high-strength carb soak cleaners will "melt" the balls outta the drain hole.

Would you believe John Deere sells replacement filter??? p/n 95-78. ($5, cheap) you just putter in the hole and gently "whacker" with hammer and punch, this spreads the metal filter out and will stay there until you melt it again .......Dell

 

[R Geiger]

One of my 8N does not have the cindered drain plug in it. next carb overhaul I may replace it! It is beter to have the open hole than to have it plugged with a screw. If you are running in real dusty conditions then by all means put the cindered drain back in. I do not run that machine in dust so I don't worry about it too much. The machine I use or mowing has it. Opions may vary!!

 

[R Geiger]

Dell , I soaked one for at least two weeks in new NAPA carb clearner and it did not touch the bronze insert. wished it had. It is plugged solid. Carb cleaners are not what they used to be. Thanks the lawyers for that!!

 

[TSnyder]

I think i may have everyone confused on the screw / sand plug part... i think i was confused myself so i thought i would share it. I am actually just talking about the smaller drain plug located opposite the main drain plug. Someone must have lost this at one time and just jammed a longer pan head screw in there. It doesn't seem to seal it like it should and the threads are longer so they probably are up to high and are interfering with the main mixture screw.

Sorry JMOR i had to use your picture from your teardown to help show what i'm talking about...

 

[JMOR]

(quoted from post at 12:50:32 06/02/11) I think i may have everyone confused on the screw / sand plug part... i think i was confused myself so i thought i would share it. I am actually just talking about the smaller drain plug located opposite the main drain plug. Someone must have lost this at one time and just jammed a longer pan head screw in there. It doesn't seem to seal it like it should and the threads are longer so they probably are up to high and are interfering with the main mixture screw.

Sorry JMOR i had to use your picture from your teardown to help show what i'm talking about...

Certainly can interfere with flow if goes too far in. 8-32 x 15/64 slotted head plug.

 

[Dell (WA)]

Tyler........yep, the "sinstered bronze" filter is on the right. The little screw yer talkin'bout is p/n: 357378-S, 8-32x1/4" (filister head). And yes, iff'n too long will clog yer mainjet ........Dell

 

[CMM]

When you have carb problems, send it to Gary (GB in MT). Reasonably priced and it will come back as good as new.

 

[TSnyder]

Thanks Dell and JMOR for the size info, i'll pick something up that fits the ticket a little better. With any luck i'll be plowin and a mowin' in no time.