intermitent miss (sputter) no load ONLY!

NO ONE posting _Knows_ the cause!

This "sputtering" is at idle (400rpm) & some at a slightly higher idle with NO LOAD. Any slight load causes the sputter to completly disapear! Also will sputter down hill, clear up after level (float is fine).

Several N experts recite begenner trouble shooting tips like rursery rymes & some have just said it is the nature of the beast, they all doit. It really is just a pet peeve as it is my only problem left after 15 years of having this tractor.For years I assumed! it was valves, till I pulled the head & valves & replaced & lapped them.NO CHANGE.

I suspect this is a cam/gear slack/dist timing issue....just from the no load only apearance.

Hopeing someone here can shed some REAL light other than saying something over & over real in 'cute'venacular.

I have done much work including,
MMO for freeing valves,lapped valves,rebuilt carb & re-checked again & again (including lapping the halves),installed Petronics Electronics Ignition, re-replaced the AL437 plugs (gapped .025 & tried .030,.035). The front mount dist has new bushings & weights are free & working, new solid core plug wires. Several good coils.Timing is correct & rechecked.

^Henry^...last night....built in '47 but'48 model
SN 34055.

Thanks to all that took time to reply, many more than I expected!!!

I think many were good replys, just things I've already eliminated.

From here I will drill & tap my replacement manifold & buy a vacuum gauge. If that helps I'll report back what I find.

If that gives no help I will (soon I hope) do a complete valve job w/new valves,1 piece guides & all the other parts. I am planning (Iza Gonna) rebuild anyway, just waiting to get it together to do it right 1 time ...stem to stern.

I kinda hate to rebuild cause he runs so good, but I really want to paint ole Henry & engine rebuild is a big b4. That & steering are about all the major stuff left.

Thanks a lot, you gave me a lot to ruminate on.

It is not too rich. In fact plugs confirm as they are grey tan, idle adjustment needle is air, can open it up and problem gets worse/exagerated. I worked real hard on the carb to get it richer cause I felt if anything it was too LEAN. Many jet sizes tried & the float has been tried over & under the stated 1/4".

I am now convinced after many hours of carb tweaking from very rich to very lean that it is nothing to do with mix. Also all variations tryed, & standard spraying of WD40 everywhere possible around manifold/carb/throtle/choke.

Thanks for the suggestion

I 'heard' that one too.

Will get vacuum gauge tomorrow if I can find one.

Will do!

Please, please, please do not take offence at this, but if you had bell-mouthed guides and then went in there and "lapped" your valves and seats, you have actually compounded the problem instead of helping solve it.

Lapping, without first having the valve in absolute perfect alignment with it's seat, is just "wobbling out the hole" more yet and is just 'adding' to the wear, so to speak.

Allan

No offence taken

I did do some light polishing on my other tractor, a 134 OHV 641 and it does not sputter. It could be the non OEM manifold.

I have been fighting this problem for about 2 years. I can tell you that they don't all do it. Mine didn't used to do it. I have the exact same symptoms as you and then some. Mine will also sputter at half throttle and need some choke to run smooth. The only thing I have not done is a complete valve job. I am about to the point of ripping the motor out and doing a "complete overhaul". I think it is a valve problem. Mine used to hold back/run smooth when going down hill, not any more.

My problems started a month or two after I installed A sherman over/under in my tractor. I was in a rush to get it back together to get hay raked. In my rush I didn't get the metal air intake tube all the way in the rubber hose under the hood at the air filter. It pulled out sometime while raking hay, hence no air filter in line. It was not in dusty or dirty conditions. The miss/sputter did not show up right away. I can only guess the lack of air filter let some dirt or grit in and pitted the valve seats/valves and it has slowly gotten worse.

Alot of people around this area don't like the little ford 8n's. lots call them "farting ford 8n's" Well if they all run like mine does now I would agree. That's what makes me mad is knowing it can run great/smooth because I have seen it.

I also wanted to put a vaccum gauge on the motor but have not gotten around to it yet.

Hope you can find something. I am about out of options except a complete rebuild.

This is what I wanted to find out!!
I lapped the valves but did not do a complete valve job. Also wanting to do a full overhaul, just dragging my feet cause otherwise it runs great.

Alan in NE suggested a worn valve guide, I sure have some of them.

I feel your pain! Just feel much better knowing someone else out there is tired of the sputter also. Your comments about the farting fords could be why I couldn't get any well thought responses on the N board, except one person said they all doit! The gordian knott of the N's??

Thanks to everyone for responding. I'll be fighting this till I die or I get it.
You can be sure if I fix it I'll buy time on TV to tell the world. Ok, maybe only tell it here, but often & LOUDLY!!! *<80)>----rasputen

I have rebuilt the carb several times. All bushings & seals are new & no air leaks. Tried WD40. Retorqued the manifold & got excited when I found a stripped brass nut. Replaced & torqued all but no change. This sputter has been going on for 15 years w/ various upgrades not changing it a bit. Replaced the manifold a few back & fixed the inherent #4 exhaust deteriotion on block,no change.

ALL jets changed, inspected, cleaned, looked at with microscope ect....cleaned ALL passages with carb cleaner/air/guitar strings...even tried diferent sized idle jets to get richer mix as it is always a bit lean (TSX 33), changed my idle/air setup to get it right w/new jets but never any change to the idle sputter.Tried various economizer jet sizes & even plug/screw in economizer port where jet goes. All these changed the way the carb acted & setup to get it adjusted but never changed the sputter. Had no main jet at bottom of main needle,just empty hole w/no threads(???) (jet is under nozzle). Tapped the hole & installed correct main jet, this provides better main jet adjustment, but NO CHANGE in ANY operating range!!!! This carb is unbeleavably forgiving.

Tractor runs like a top!! Awsome power, just the anoying sputter intermittently at _NO LOAD_ idle or fast idle.

This is just a thought; I've only seen this once before, way back in the 60s and your symptoms nail it to a tee.

Put a vacuum gauge on that thing; if the vacuum drops right when the sputtering is going on, but comes right back up when she clears up, I still think you have a valve problem.

Not a "valve" valve problem, but rather a sloppy guide. If it only does it just at that one, low, "just kinda off idle" speed.

The rotation of the cam is forcing that valve follower sideways, which in turn pushes the valve in it's guide just enough to "cock 'er", which drops the compression, & it makes 'er sputter. Any more speed and she then lifts clean and your sputter goes away.

To really check the guides, have the keepers and springs off and lift the valves just an eighth of an inch or so off the seats. This is the point of most wear and there should be absolutely no sideways play in those stems/guides.

Those guides really get ignored in those old flatheads

Allan

I did check & had "some" guide wear.Want to do a full engine rebuild & I DO mean COMPLETE! Just hate to not have this tractor running as I am way too attatched to it, (stoopid since I have another tractor as backup).

Thanks again for makin' me work so hard!! *<80)>

E.g. refine the carburetor settings indirectly.

Gerald J.

Thanks for the reply:
Tried that! Even tried opening jets to get overly rich mix as the idle jet is air & can add a lot of air from where it is!

I can rich it up till it starts stumbling and almost dies. NO carb setting will correct the INTERMITTENT Miss. Very short miss, like it just missfires on 1 stroke on 1 cyl intermittently.

Carb is MS TSX 33. Carb has been worked over A LOT as in even several larger jets tried to correct a possible LEAN problem you described. Had problem for 15 years, clears with even slightest load!

I have a '65 F-350 with the block changed to a 390 and some other 4 barrel carburetor. It sounded like it was rich at idle causing it to run poorly after a while, but actually it was running lean and the cure WAS raising the gas level in the float bowl.

Maybe you need to be sure the voltage regulator is set for 7.2 volts and keep the headlights on to give the engine a bit of load to let the governor open the throttle off pure idle.

Gerald J.

Don't have exotic manifold, just 4 or 5 year old regular replacement non OEM Tiawan or somplace like that.

Don't think I want to run the lights even if that cures it, running the PTO in very cold wether 'fore it warms up gives it a slight load.(GL1)

Thanks for the response.

One of my pet peeves is just that on a non-fuel injected gas engine. Runs fine but pffst intermittently at idle

The way I solve that problem is to install an electronic ignition with the high voltage coil option(Genessee works fine with their 40kv coil). Then I get some plugs [like old ones I run (ran) in my Dodge p/u] that have a deep snooz and set the gap to about .060. I always check the piston top clearance before I do this to insure that the plug will not interfere with TDC on the piston (Stick a stick down the plug hole and "find" the piston top, then measure clearance).

Puts out one heck of a smack and it's down in the combustion chamber where everybody can get a whif of it and she ain't a missin no mo.

Do every gas tractor I get as a matter of course upon arrival. Bonus..... ..... .no !@#$%^&*()_+ points to mess with!

Mark

Good hot blue spark! I ran my AL-437's up to .040 but went back to shorter gaps TS'ing this while working the carb EXTENSIVELY!

I can try that eazy enought as I am running 6.5 compression at best.

Out of curiosity, have you tried to isolate which cylinder might be missing. If it always the same cylinder, it could be some sort of manifold leak (gasket or pinhole) on the runner leading to that cylinder. Sometimes spraying something like WD-40 on the manifold will uncover such leaks.

I have shorted each plug independantly, none seem to cure the symptom. All plugs slow it down but # 4 seems to really slow it down.

Still, no plug isolated the sputter.

steveormary

It may be the nature of the beast.

Ken

Ken

For years I thought it was a burnt/sticky exh valve 'cause it will pop a piece of paper at the tail pipe. Been wondering if it is just inherent in the manifold design.

BTW: My 134 CID OHV Ford 641 does NOT have this problem.
Thanks.

Bypassed the New ignition switch several times looking for an easy fix. BTW been thru 3 switches in the 15 years I've been trying to get rid of this 'sputter'.

Also remember, it COMPLETLY goes away under any load!!! Even lugging in low gear at idle NO MISS.

Thanks again for the replys, been thru a LOT of things but willing to get all suggestions.

It is Steve who works (lurks?)on the tractor board. The tractor I had the problem with was a 1952 TO-30. We used to think it was the leaded gas that would cause plugs to short out and miss. But it sounded better then the,nevermind.

steveormary