8n running rough at full throttle

DCarr · Oct 15, 2019

New plugs, coil, points, condensor and carb. Followed instructions in setting timing. Approx + 10 degrees at 1000 rpm. When opening throttle full it misses. No power. Have set gas gets to requirements. Runs smooth at 3/4 throttle. Need help. I have received excellant advice from your site and I thank all of you for your knowledge. One more item, the distributor is against right stop. (side distributor)

David G · Oct 15, 2019

Did it do this before you worked on it?

old · Oct 15, 2019

Side mount point set to 0.025 correct?? Does choking it hurt or help?? Any black smoke from the exhaust?? Firing order correct as in 1,2.4,3 with the #1 cylinder being by the radiator.

Do you have a good blue/white spark form the center wire of the cap and at all 4 plug wires that jump a 1/4 inch gap or more.

If you pull the carb drain plug do you get a good steady flow of gas that will fill a pint jar in less the n3 minutes??

When was the last time you serviced the air cleaner and dumped the mud and water out and filled with fresh oil

Steve@Advance · Oct 15, 2019

Revisit the points.

Check the distributor shaft for side play. If it's loose, the points won't stay set, will do strange things at various RPM.

Try an old condenser. Is the condenser tight to the base? It must have a good ground.

Look at the points, double check the connections, or replace them again.

The new points and condensers are known for being bad out of the box.

JD Seller · Oct 15, 2019

I will also add trying a different coil. I have had them cause a miss like this and it sounds exactly like a fuel problem, when it is the coil breaking down under load.

Sprint 6 · Oct 16, 2019

Do 8Ns have the ballast resistor like 9Ns do? I chased a 9N around with a problem like that before I found out they had a ballast resistor, even on 6 volt.

Leroy · Oct 16, 2019

Don't know why others that are more mechanicks than I am did not say anything about your last statment, distributor against stop. It should never be against stop on either side but in middle of travel. This is same for any engine, car or tractor. Against stop says that the distributor is timed wrong either by getting it one tooth off ininstalling or having cam shaft one tooth off. Either way at full throttle it cannot advance disrtibutor and spark far enough for what it needs to run good. Full speed needs more advance than only 3/4 speed. Did you pull the distributor when you put in the points?

Tony292 · Oct 16, 2019

(quoted from post at 19:20:44 10/15/19) New plugs, coil, points, condensor and carb. Followed instructions in setting timing. Approx + 10 degrees at 1000 rpm. When opening throttle full it misses. No power. Have set gas gets to requirements. Runs smooth at 3/4 throttle. Need help. I have received excellant advice from your site and I thank all of you for your knowledge. One more item, the distributor is against right stop. (side distributor)

Try giving it some choke when full throttle and see if that helps. If so, it may be leaning out and need to adjust carb.

DCarr · Oct 16, 2019

Yes it has been out several times while trying to set timing. It also has a lot of play in moving shaft. Should I reset dist shaft? I set flywheel on 0 degrees after 1st cylinder was DTP. Inserted dist shaft in with rotor pointing to 1st cylinder, rotated shaft till points sparked then proceeded with timing light using 1/2 throttle setting flywheel to +7. After checking dist it was against right slot, can not go any further.

Leroy · Oct 16, 2019

Sounds like it needs new bushings and possibly gears and reset timing.

8n running rough at full throttle

DCarr

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David G

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old

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Steve@Advance

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JD Seller

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Sprint 6

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Leroy

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Tony292

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DCarr

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Leroy

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