TRACTOR SPARK PLUGS

Mark Littlejohn · May 25, 2009

WE JUST FINISHED A GROUND UP RESTORE ON A JOHN DEERE 430s AND STARTED IT BACK UP THE PLUG RANGES WE THINK ARE WAY TOO HOT FOR THIS OLD TRACTOR USING AN NGK HOTTER plug the manifold got very hot and we wondered if going back to a champion H10C or an autolite 216 might solve this problem can anyone shed some light on this subject for me thanks for any help you can suggest.

TractormanNC · May 25, 2009

Spark plug heat range will have no effect on how hot the manifold gets. Make sure the timing is set correctly and the carb is adjusted properly, should be good to go then.

jbp · May 25, 2009

Doubt its the plugs causing a too hot manifold. Sounds like ignition timing is way too slow. Check timing.

Jon Hagen · May 25, 2009

And that the spark advance is working. Nothing will turn the exhaust manifold red hot faster than no spark advance at speed.

RobMD · May 25, 2009

There is NO spark advance on ANY tractor with a delco distributor.

Anonymous-0 · May 25, 2009

Question for Rob:: Are you sure there aren't spring-loaded weights under the rotor plate which advances the timing as soon as the engine begins to run? I realize that there's no vacuum-actuated advance like there is on a car.

Bob Collins · May 25, 2009

Delco distributors do indeed have machanical advance commonly called centrifugal advance from the weights "throwing" outward with increased speed and thus advancing the shaft and cam. This opens the points sooner which means the spark plugs fire sooner hence spark advance. Generally vacuum advance is for lower speeds and mechanical advance occurs at higher speed.

Bob · May 25, 2009

You be thinking of "vacuum advance" vs. "centrifugal advance", as I don't know of a Delco tractor distributor WITHOUT centrifugal advance.

John T · May 25, 2009

Yo Rob, where you get that info?? The Delco distributors I've seen use a mechanical centrifugal spark advance !!!!!!!!!

John T

Jon Hagen · May 25, 2009

Use a timing light to check the initial timing setting at idle, then keep the light on the marks as you slowly increase rpm to full speed. Timing should smoothly advance until it indicates 25-30 degrees at full rpm.

If spark does not advance as rpm increase, you have found your hot exhaust problem.

If the advance mechinism is stuck, remove the point plate and soak all the advance weight pivot pins with solvent oil. Also remove the rotor and little felt disc in the end of the hollow rotor shaft, soak the hollow shaft with solvent oil.
A small vice grip locking pliars lightly clamped to the rotor shaft helps work the sticky mechanism to free it. Once loose, lightly oil the weight bushings and replace the felt disc in the hollow rotor shaft. drip 3-6 drops of motor oil on this felt pad every year. Lubing that felt pad is oftem missed and is the major cause of stuck spark advance mechanism.

You should be able to grab the rotor and twist it 10-15 degrees in the direction of normal distributor rotation. The weight return springs should snap the rotor back to the idle timing position when you release it.

Brian Jasper co. Ia · May 25, 2009

There is no spark advance on a magneto. The impulse retards the spark for easy starting. Every tractor distributor has a mechanical advance. Some Oliver tractors did have a vacuum advance. I think they were using a Mallory dist though.

John B. · May 25, 2009

I've never seen a distributor without any advance. Spark has to advance cause gasoline only burns so fast. So the fire has to be started earlier at higher engine speeds so maximum combustion takes place when the piston is at it's maximum torque range in relation to the crankshaft angle.

John B. · May 25, 2009

Some magnetos have an advance don't kid yourself. If you ever seen a mag run on a test bench you would see it in person like I have.

The impulse is only there to give the mag a quick spin when the engine is being cranked at low rpms. If the mag didn't have the impulse at this low rpm it would not create a spark hot enough to jump the plug gap.

The International F4 & F6 mags had a manual spark advance.

Anonymous-0 · May 25, 2009

Just where have you been saying there is no advance on a Delco Dist. You must not have one on a tractor.

Janicholson · May 25, 2009

With Respect, I beg to differ. Every one I have seen have a set of weights and springs in the housing under the breaker plate. Mags often do not, but they are full advance after the impulse coupling disengages.
Without an advance the tractor would either back against the starter something fierce, or run really poorly all the time. earliest tractors had manual advance levers to do just that. JimN

Anonymous-0 · May 26, 2009

Chevy sixes moved the entire distributor to advance the spark in the mid 50s.This movement often broke the coil wire.

TRACTOR SPARK PLUGS

Mark Littlejohn

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TractormanNC

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jbp

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Jon Hagen

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RobMD

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Anonymous-0

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Bob Collins

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Bob

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John T

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Jon Hagen

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Brian Jasper co. Ia

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John B.

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John B.

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Anonymous-0

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Janicholson

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Anonymous-0

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