How to check/adjust Timing

[Roshambo]

Good Morning,

I've never adjusted timing before, I've got the 75 IH Cub running very well, having replaced the points (gapped them), condenser, spark plugs, wires, distributor cap and rotor. However, I'd like to ensure timing is on point. I've got a timing light on order and I know how to set the engine to top dead center.

I've never timed an engine before, does anyone have a link to a post on here that explains how to check/adjust timing with the light?

Thanks!

-Chris

[Slim140]

Hook the 2 battery wires on your timing light to the battery or hot wire on starter and ground on a good known ground and hook the wire with the clamp off the timing light onto the #1 spark plug wire (it's the front one on a Cub) and point it to your harmonic balancer in this case on a Cub the front pulley on the crankshaft and you should see a notch on the pulley and the point off the front of the engine. They should line up. Adjust distributor accordingly to make them match and your set. It helps if you can find the notch on the pulley before starting and put some chalk on it. The timing light wire for the spark plug if it's the clamp over the wire kind may have an arrow on it saying "towards spark plug" if it's the kind that goes in between the spark plug and spark plug wire it doesn't have a direction. The notch on pulley and pointer on front of engine are on the opposite side from the distributor on a Cub making it harder to adjust. You may have to turn the distributor a little and go to the other side and check marks. Here's the wires and clamp I speak of on my timing light.

[Roshambo]

Thank you sir! Didn't mean for you to have to type all that out. I figure there must be an old post here I just couldn't find it.

[Winfield Dave]

Maybe it is time to download and read the free owner and service manuals.
Also search for posts. Chances are someone has already asked the same questions.

[Slim140]

Maybe it is time to download and read the free owner and service manuals.
Also search for posts. Chances are someone has already asked the same questions.

Well said Dave

[Roshambo]

Already been through the manual a bunch of times. Purchased a paper copy from TM Tractor Parts, I didn't see any instructions on how to check the timing. I didn't know there was a service manual, I will go find it. Thanks!

[Bill V in Md]

Already been through the manual a bunch of times. Purchased a paper copy from TM Tractor Parts, I didn't see any instructions on how to check the timing. I didn't know there was a service manual, I will go find it. Thanks!

Yeah I quickly researched previous posts as well as the How To Section and could not find any detailed instructions (aside from above post by Chipmaker) on timing a cub with a timing light. There are a lot of references to using a timing light, but detailed procedures are lacking. Fortunately, most timing lights come with detailed instructions that you can adapt to your particular cub. Most timing lights are 12v and a lot of cubs are 6v, so you would have to utilize an external power source for a Cub with a 6v battery. However, I am assuming your 75 Cub is 12v, so Chipmaker has you covered.

[Roshambo]

Roger that Bill it's a 12v. I too couldn't find a post. I'm working on the tractor a lot so I've been posting a good bit, hope I'm not taking advantage.

Thanks again for all the help.

[tmays]

I find that doing a google search gives better results than searching here on the forum. And usually get links to posts here on the forum

[Roshambo]

Thanks Tmays!

[Eugene]

Rather than taking 30 or more minutes to write up a lesson plan, then lecturing for an hour. The entire process takes about 5 minutes. A show and tell, hands on demonstration, is the way to go. Takes about 5 minutes for the demonstration and another 2 or 3 minutes for the student to copy/duplicate the lesson.

If you can locate a nearby Cub owner, contact him/her and ask for a practical demonstration/exercise in timing the Cub.

I use to teach shop/Industrial Arts/Industrial Technology and auto mechanics at a junior college. Most of my classes were started with a short explanation on how it worked and a demonstration, then a practical exercise replicating the demonstration. I always got dinged by the administration for not giving lengthy, in depth lectures.

I searched the internet looking for a demonstration on using the timing light to adjust the Cub's timing. No avail. Not even a demonstration on static timing a battery powered ignition system. What I did find was demonstrations on how to set the points and correctly install the distributor.

[tmays]

If you're interested, here's how to static time battery ignition.

To static time battery ignition, I do the following.
Bring number 1 piston up to TDC on compression stroke. Rotor should be pointing to number one tower on distributor. Loosen bolt holding distributor so it can be rotated. Turn distributor clockwise a little. Turn ignition switch on. Pull number one wire from plug and while holding wire close to ground, turn distributor counterclockwise until you get a spark. Tighten distributor down.

[Glen]

Hi,
I have written on here before about timing a Cub with a Battery Ignition unit. Here it is again, but a little more detailed.

It is really not hard to time the engine.
To time a Cub engine, first read the instructions for the timing light, and hook it up correctly.
Mine has wires that attach to the battery, 12 volt power, and a third wire that attaches to the number 1 spark plug wire.
You have to run the engine at low idle speed and point the light at the timing marks on the front engine pulley.

Below is a page from the Cub service manual GSS-1411 showing how to time it. It says in the note on the right on the page that the final timing adjustment must be made with a timing light.
The mark number 1 should be aligned with the pointer when the engine is running at 450 RPM. They are talking about something else on the right side of the page, disregard the words, except for the note.

http://www.farmallcub.info/manuals/gss- ... 001-43.jpg

To adjust the timing, you have to loosen the 2 bolts that hold the 2 clamps on the round part of the distributor, one bolt is on the engine side of the unit, it is sort of hard to get at. A short box end wrench works there, or a curved wrench, John has shown a pic of one before, I think. Then you turn the round part of the distributor to change the timing.

You should tighten one bolt slightly when the engine is running during the adjustment, so the unit doesn't turn by itself, when you are not at the distributor.

After timing it, and tightening the 2 bolts, you can check and see if the spark advance is working, by pointing the timing light at the mark and slowly speeding up the engine to full speed. The spark should slowly advance as the speed goes up, until the mark number 2 in the manual pic is about in line with the pointer.

If you have an earlier 1950's Cub with 1 timing mark on the pulley, it should be the TDC mark, you can guess where the 2nd mark would be from looking at the pic in the manual.
If it does not advance, the parts in the distributor are not working, sometimes the shaft that the rotor is on is frozen in place. It is supposed to turn slightly. The parts of the advance are shown in the Cub parts manual.

[Roshambo]

Extremely helpful! Thank you all!