At wits end

Hello, I'm new to join but have read posts for a long time. I've got a tractor that has me pulling my last hairs out!! :shock: :?
1948 8n front distributor
12v converted
motor rebuild less than 100 hours.
Only use to bush hog 3 acres and drag driveway.

So, Tractor was running fine,started right up,ran good through rpm range. I just started the bushogging this year but have owned the tractor since 1999. At the end of the last bushhog job I noticed something didnt sound quite right,like it couln't get to full rpm. I cut in 1st gear with a 5' bushhog. Anyway I get done and park it under a cedar tree at the house then Hurricane Erma's remnants rolled in(im in Middle Tennessee). We got 6" of rain over 3 days with temps in the mid 60's. After the storm no spark,dried the distributor enough to start it and move it about 6 feet and it died.Long story short I went through everything electrical,new plugs,wires,coil,cap, rotor,points and even a new distributor. Gap at points is .015 plugs.025. Checked fuel flow and changed bowel screen and elbow screen,blew compressed air up fuel line to clean out intank screen. Then I rebuilt the carb after soaking it 24 hours in carb cleaner. I got it all back together and it would start and idle ok but would backfire and popcorn at higher rpm.At that point I noticed I had a blown manifold gasket on#4(toward steering wheel) Fixed that and put a new carb on it,now it starts and idles fine but still stumbles and backfires at high rpm unless I pull the choke out a little,then it runs fine. Idle needle was turned out 1.25 turns and I messed with it to get a good idle. The main needle started at 1 turn off bottom and nowhere in its range could I get it to run good at high rpm without choking it a little. I drained every bit of the gas out last night and put it in the truck to burn it up(about 4 gal) and am gonna get 5 gal of straight gas today treated with stabil and see if thats the problem but the gas was new at the last cut. If new gas don,t do it where do I look next????

Being able to make it run better with some choke says two things to me, 1) power circuit still obstructed in carb resulting in lean condition or 2) weak spark, because a richer mixture is easier to light off. I have not included a manifold leak, because you have just replaced manifold gasket, so assumed that was a good job.

"even a new distributor."

What was wrong with the old dist? New, as in new offshores built, could be the problem. I have a bunch of front mount 9/2/8
Ns. I don't trust any new distributors, carbs, starter motors, governors, etc.

Not being able to reach higher rpm's can be caused by a plugged exhaust system. This might be why you blew an exhaust gasket. Try
dropping the muffler assembly just and see if it will rev up like it should. Be sure the carburetor air intake is hooked up while
running. Is there a chance you might have ran over something and damaged the muffler or tailpipe?

Slop in the bushings,it looked original. I don't have the tools to change the bushing and if I bought them I might as well get a new one.

New muffler too!

Well it isn"t bad gas. I got 4 gal of no corn gas,same thing,stumbling,popping,light backfires at high rpm? Pull choke out a tad and it runs better,
not right but better. Push in the choke and the stumble pop backfire come back. Also noticed governor is hunting? I don"t know where to look
next.

Might check that gasket in carb, between bowl & top part, is properly in place as well as venturi.

It could be a lot of things . I have noticed a bad gap in the points makes one run rough under a load and or high rpm . I have gutted my coils and run a no resistor needed round can coil . The ability to hook up a dwell meter takes all of the guessing out of "Is it in my distributor"

Have you tried running it with the gas cap loose? Could be that the vent in the gas tank is plugged.

Well, in my opinion, non-ethanol gas isn't a factor. Also, no 'snake-oil' product like STABIL is needed either. Those are not the root causes of your issues and not needed. Everything got wet right? That means distributor, carb, and even the hydraulics could have been contaminated with water. Just throwing all new parts into the mix is no way to proceed with a root cause problem solving method. You take one system at a time and thoroughly diagnose it. Like Harold said, what was wrong with the old distributor? New carb? Same question -why? The original parts are made to be rebuilt over and over and always a better choice than buying anything sold today aftermarket. When you did all those 'changes' did you use your I&T F-04 Manual, 8N Operator's Manual, and MPC as guides? Carb adjustments are made when engine is hot and must be done 3 or 4 times with a cool down period in between. You just don't set the preliminary settings as set forth in the manuals and think it is good to go. I don't believe the manifold gasket was the root cause but did you use new gaskets, brass hex nuts, and torque to correct specs? Torque specs are 27 ft/lbs. Torque is set correctly when done in three settings. Once assembled, get engine hot then cooled down. Go back several hours or better yet, the next day and recheck torque. By your previous post, I suspect you have the plug wires/firing order incorrect. I usually cringe when I see a 12-volt convulsion job on a tractor. 9 times out 10 that usually turns out to be a huge factor in non-running/starting issues. Go back over the basics starting with wiring, a fully charged good battery, and correctly set distributor. Leave the carb alone, for now anyway. Put main Jet Mix screw at 2 turns and Idle Air at 1-1/2 and leave them.

Tim *PloughNman* Daley(MI)

(quoted from post at 04:04:49 09/21/17) Well, in my opinion, non-ethanol gas isn't a factor. Also, no 'snake-oil' product like STABIL is needed either. Those are not the root causes of your issues and not needed. Everything got wet right? That means distributor, carb, and even the hydraulics could have been contaminated with water. Just throwing all new parts into the mix is no way to proceed with a root cause problem solving method. You take one system at a time and thoroughly diagnose it. Like Harold said, what was wrong with the old distributor? New carb? Same question -why? The original parts are made to be rebuilt over and over and always a better choice than buying anything sold today aftermarket. When you did all those 'changes' did you use your I&T F-04 Manual, 8N Operator's Manual, and MPC as guides? Carb adjustments are made when engine is hot and must be done 3 or 4 times with a cool down period in between. You just don't set the preliminary settings as set forth in the manuals and think it is good to go. I don't believe the manifold gasket was the root cause but did you use new gaskets, brass hex nuts, and torque to correct specs? Torque specs are 27 ft/lbs. Torque is set correctly when done in three settings. Once assembled, get engine hot then cooled down. Go back several hours or better yet, the next day and recheck torque. By your previous post, I suspect you have the plug wires/firing order incorrect. I usually cringe when I see a 12-volt convulsion job on a tractor. 9 times out 10 that usually turns out to be a huge factor in non-running/starting issues. Go back over the basics starting with wiring, a fully charged good battery, and correctly set distributor. Leave the carb alone, for now anyway. Put main Jet Mix screw at 2 turns and Idle Air at 1-1/2 and leave them.

Tim *PloughNman* Daley(MI)

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hanks for the input,I went by the 04 manual but used the steel nuts that were on the manifold.I dont have a torque wrench so I did that just firm and checked them after a heat up/cool down. I swapped the distributor cause the old one had a lot of slop in the bushings. As of last night it will start right up and idle perfectly but up the throttle and the sputtering and backfiring start,same with either carb.

Red.......yer spittin' & backfiring is symtomatic of LEAN carbie. Learn to set yer carbie. Here's how I recommend. Set the down-pointing mainjet to 2-turns and LEAVITT!!! Adjust the side-pointing idlemix fer FASTEST idle NOT SMOOTHEST idle. Understand the difference??? Usually will be about 1/8-1/4 turn. BRASS NUTS are recommended fer yer exhaust manifold 'cuz steel nutts will corrode and you'll end-up un-screwing the studs from the block. BRASS-NUTS will STRIP and leave yer studs inna the block and not leak all yer radiator fluid out. Simple, eh? .......Dell

(quoted from post at 09:23:31 09/21/17) Red.......yer spittin' & backfiring is symtomatic of LEAN carbie. Learn to set yer carbie. Here's how I recommend. Set the down-pointing mainjet to 2-turns and LEAVITT!!! Adjust the side-pointing idlemix fer FASTEST idle NOT SMOOTHEST idle. Understand the difference??? Usually will be about 1/8-1/4 turn. BRASS NUTS are recommended fer yer exhaust manifold 'cuz steel nutts will corrode and you'll end-up un-screwing the studs from the block. BRASS-NUTS will STRIP and leave yer studs inna the block and not leak all yer radiator fluid out. Simple, eh? .......Dell

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Dell, I,m tellin you,I did! I did 1 turn out and tried in with no luck 1.5 and 2 the same way. I tried if at 1.5 out and screwed it in till it faltered and started very slowly backing it out and it never riched up. I unscrewed it like 6-8 turns and it was still acting lean. I double checked gas flow from the tank at the bowl and from the drain under the carb and it flows like an old man peeing. It's getting fuel to the carb. I don't know what the heck is going on? Cracked manifold that I can't see? Head gasket leaking air in? :shock: Anyway' I put copper spark plug anti seize on the stud bolts for fear of what you described,I'll get some brass ones later.

In my experience, if adjusting your carb screws make little difference in how it runs then you have a carb that needs cleaning at best, a rebuild at worst. Just went through this with my 8N, was running worse and worse until I swapped in a cleaned and rebuilt but little used carb from the 9N (the original one from the 8N) and it now runs great.

(quoted from post at 00:34:15 09/23/17)
In my experience, if adjusting your carb screws make little difference in how it runs then you have a carb that needs cleaning at best, a rebuild at worst. Just went through this with my 8N, was running worse and worse until I swapped in a cleaned and rebuilt but little used carb from the 9N (the original one from the 8N) and it now runs great.

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Totally agree with this.