756 Gasser Tune-Update...

Bill VA

Well-known Member
No joy...

Replaced the new coil which was 12V with a 6V, the exact IH part number replacement. Got spark across the points, but no fire. Replaced the new condenser with another new one, won't fire. Replaced the wire from the coil to the new distributor cap, good connection and no fire.

Got gas to the carb. Drove the tractor to the spot where I'm working on it, no issues, only replaced plugs, points, i.e. tune-up parts and the tractor won't fire or even misfire on any cylinder.

I'm thinking the plug wires are not going to the right plug - though everything is wired per the manual - pic attached.

I understand the firing order off the distributor and the cap is marked as such. Question is - is the 1-6 sequential plug numbering on the engine correct per the manual left to right? The distributor cap is what mixes-up the firing order - right?

Similar post on RP

Thanks!
Bill
a171927.jpg
 
If you open and close the points by hand do you get a good blue white spark that jumps a 1/4 in gap or more out of the coil wire?? If you have that then the problem is in the distributor. If you do not have that the problem is from the distributor back.
 
Middle of the day, hard to see, but I manually opened and closed the points and have a goodly spark. I'll try again tonight.

I'll also pull one of the plugs and see if I'm getting any spark there.

Thanks,
Bill
 
Also sprayed some starting fluid into the intake and no fire. Anything is possible, but I don't think gas is the problem here.
 
Put the rotor and cap on and then hold the plug wires one at a time close to the block or gap an old plug out to about a 1/4 inch and spin it over and see if you have spark at the plug wires. If you do then where the wires on the cap could be the problem but if you do not have spark rotor or cap could be bad
 
One possibility is that it has lost valve timing. The cam drive could have failed allowing the whole ignition system and compression to be wrong. Jim
 
Turn the engine until the rotor points to the distributor cap terminal connected to #1 plug. Look at the timing mark on the pulley and turn the engine to get it at TDC. It should have been very close. If way off,(like a quarter turn, it has jumped timing. Jim
 
Had some time to tinker with it a bit ago, before I read your reply. Keep in mind that aside from the smokey gas motor in need of a rebuild, it seems like a sound machine - new to me, but clearly neglected by the previous owner IMHO. Abused, I can't tell, but based on the condition of the plugs/wires, points, just little things like that - just not maintained and that's no dig on the previous owner, it is what it is.

Having said that, as smokey as the engine is - it has been a quick starter in the months I've owned it. A real easy starter, hot or cold. So a surprise when I put new everything electrical on the points/spark plug side, but I wired it back per the manual....

While working on another part of the farm today, I got to thinking, one of the plug wires, the #1 may have been in the #5 socket on the distributor cap, but couldn't remember for sure. So when I came-in, I took all the wires loose from the distributor and starting rotating the position of the wiring sequence, i.e. #1 in the #2 and #2 in #3 and so on - trying to start each time until I had rotated everything via the #1 wire to the #6. If that makes sense.

Bottom line - it fired off and ran, though rough, with all the wires rotated in order with the #1 wire in the #5 position - just as I thought I remembered. I was glad to hear it run as it validated everything from from the coil to the plugs were working.

Soooooo - I've never really tinkered with timing an engine with a distributor. Got a timing light.

How do I get this thing back to square one, where (as you mentioned) the #1 cylinder is top dead center at the same time as the rotor pointing to the #1 position on e distributor cap? I've got the owner's manual and an IT manual - I'll be reading and googling tonight.

Any sage advice is much appreciated.

Also posting most of this on RP too to pick-up a few pings there.

Thanks!
Bill

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The old school way to find TDC on cylinder 1 is to put your thumb over the plug hole, turn the engine slowly till you feel compression. Then continue rotating slowly to the crank pulley TDC mark and line it up. Don't know how you'd do this on the 756 except quick taps of the starter with an assistant. (Maybe pull the starter and turn the flywheel with a pry bar?) Whichever terminal your rotor is pointing to under the cap will be #1 cylinder. Arrange the wires in firing order starting at the #1 position and then time with a light.

Check your current firing order and see if it follows the proper sequence. Maybe 2 are swapped.

Chris B.
 
On a 756 there is TWO PLACES TO FIND TDG. One is on the ft vibration damper/ Pulley and there will be a BUMP /Pimple and you line that up with the pointer , Next on the right hand side of the bell housing there is a cover with TWo 1/4 inch bolts holding it on and ya need a 7/16 wrench/ socket to remove , under the cover you will find a tin / sheetmetal pointer that will come out , you do not take the pointer out and you use the two 1/4 inch bolts to hold it down and the fly wheel is marked in Degrees and TDC . NOW on a six cylinder you may be at TDC on #1 or ya may be at TDC on #6 . Also if you look at the top of the dist. real good you will see the firing order built in .
 
If you drove the tractor to a spot, changed some ignition parts, have some sparking, in my mind that points to an ignition wire mixup. The person who worked on it last may not have placed the #1 wire in the same spot as the manual.

What I would try is to take the #1 wire (closest to radiator fan) and jump it either CCW or CW one hole in the distributor cap. Then the remainder have to fall in order going CCW around the top, 1-5-3-6-2-4. Now try to start.

If that doesn't work, keep moving the #1 wire one additional hole in the same direction around the distributor cap, placing the others in the proper CCW sequence, and repeat. Eventually you'll find the proper spot where #1 wire was formerly located.

If this technique doesn't work then its time to find the "correct TDC" on the #1 cylinder with no intake or exh valve motion either side of the top of the stroke and reset the rotor to where the book calls out #1 cylinder.
 
That is a good way to get a kick back & break the starter nose. Pull the #1 spark plug & find compression & go from there.
 
This is why I don't rip all the plug wires off the tractor at once. Rather, I replace them one at a time so it is impossible to screw them up.

New ignition parts usually change the timing some, and I would also suspect that you may still have a couple of wires messed up.

Please, stop ripping off all the wires at once.
 

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