Generic gasoline engine tuning question

[CharlieS]

Before you delve into the carb, have you done a complete ignition tune up? you mentioned a plug replacement but what about coil, points, rotor, cap and wires? Timing? All these can create the conditions you mention. Be sure you have the right heat range plugs also as cold plugs won't have the hot spark necessary for effecient combustion.
Start the tractor and pop the hood up in the dark of night and look for spark leaking from the wires, bad wires will show spark leakage in the dark.
Check for water in the fuel & add a good fuel filter if one isnt present.
After a complete ignition tuneup if the problems still exist, then look at a carb rebuild. Many times carb's are the first suspect when in reality lack of good ignition creates false symptoms.

 

[284 International]

I haven't done any other adjustments or tuning except the new plugs, air and fuel filters. The fuel is clean (I've even run it from a separate container other than the fuel tank) and fresh. I don't know what heat range plug is correct, since I can't find any of that information online, but put what it had previously had. I haven't checked the ignition timing or anything else. The engine doesn't run roughly as one does when a plug or plug wire is bad, it feels like a fueling issue, but I can't rule out ignition woes. Do these distributors have a vacuum or mechanical advance built in besides the physical timing advance of the distributor setting?

 

[lostcause]

the most basic of tests for a rich/lean condition is the choke. get the tractor to the point where you are going to put a load on it and cause it to stumble. just as it is stumbling, hit the choke. if the choke helps the problem, then it is most likely a lean condition, and if it stumbles/gets worse, then it is most likely a rich condition.

i know there was mention of soot already, indicating a rich condition, but it's always possible that it's running a little rich at low speed/idle, where it spends a lot of its time, but may be a lean condition as it goes toward high speed.

 

[Egon]

Tractor runs. Twiddle with the carb jets.

 

[lostcause]

Tractor runs. Twiddle with the carb jets.

if you choose this approach, make sure to leave any implements raised a little. that way, if you end up making it so the tractor will not run at all, then you will at least be able to push it out of the way if needed.

 

[284 International]

Lost Cause, that's the best advice I think I've heard in a decade or more. (To leave the implements up) The choke makes it worse, and is unnecessary to start cold, even when sitting overnight. To be fair, it gets "down" to only 60 degrees or so here, so "cold" isn't COLD.

 

[RPW]

TBNer's have given you good advice however my 2 cents are to get a manual. They're available online.....somewhere..... keep looking. If you want to delve into this without look for similiar auto engines or similiar carbs. You might be able to get the specs. to use as a baseline. Also like someone said check points, coil etc. Insure that you have the correct parts (coil etc.). Clean everything as best as you can. Any dirt in the carb will cause problems. Also insure that all hoses, filters and tanks are clean.

Good luck.

 

[pat32rf]

I just went thru much the same thing with an old Kohler motor. My mechanic explained over the phone, that the idle jet was too rich. When you tried to speed up or increase the load, it would start to flood out. It will be the adjustment screw closest to the engine (if you have a choice). Its between the throttle plate and the intake manifold in the fuel circuit...
Thats about the extent of my carb knowledge......learned over the phone

 

[284 International]

RPW, I didn't intend to come across as ungrateful. Thank you for letting me know it seemed that way. I apologize. To any who took it that way, I'm sorry and it wasn't on purpose. I really appreciate the tips.

I've got several directions to go now. A trip to Napa yielded nothing in the way of parts, for either the tractor itself or equivalent parts from any Mazda brand vehicle listed. Does anyone know of a source for any parts at all, or, better cross-referenced parts to other applications, if any? There isn't a Case-IH dealer for nearly 200 miles from me.

I think I've managed to find a manual at a semi-local library, of all places. I will pick it up tomorrow (If it actually is for this tractor) and proceed from there. If not, I guess I'll start with the carburetor, so after fiddling with the jet needles (I'll write down and/or mark their starting position) will disassemble and clean everything. Then, pull the points and condenser, replace the coil, wires, and get the next warmer range of plugs. If that doesn't fix it, I guess I'll just be stuck. Thanks again to all who have responded so far. Any other ideas or suggestions?

 

[Jim Thompson]

My first action, from what I understand, would be to check the points and condenser. Isolate the points and check the resistance- should read zero ohms. If you don't know the point gap, I would set them between .017" and .020". You may be able to polish the contacts with fine (4oo grit or finer) sand paper or a burnishing tool (for the old timers). Always clean the points after you set them. I wouldn't replace the coil unless correcting any problem with the points and condenser(replace) failed to resolve the problem. Coils do go bad, but in my experience, not very often.

The carb could be the problem, but I would suspect that its more likely to be ignition. If I'm wrong it certainly would not be the first time.:laughing:

Good luck:thumbsup:
Jim