Cub Carburator Adjustment

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farmergiffIV
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Re: Cub Carburator Adjustment

Postby farmergiffIV » Sat Mar 03, 2018 8:45 pm

Glen wrote:Hi,


I'm not sure if your Cub has a magneto, or a Battery Ignition unit.
There is a page in the Cub service manual about timing the engine with a timing light. :)


I finally got a timing light and now I am looking for this page in the service manual. I watched a youtube video of someone doing it on a car but I am looking for more info on the tractor before I venture forth.

Did you recall the section its under? I did a quick search and I didn't see much on the forum about how to use at timing light.
Sun Spirit Farm Manager



My '53 and '48 Cub Project

Eugene
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Re: Cub Carburator Adjustment

Postby Eugene » Sat Mar 03, 2018 9:09 pm

https://www.youtube.com/watch?v=c5gg4N7 ... jf&index=4

Wrenching with Rachael is usually very informative.
I have an excuse. CRS.

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Glen
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Re: Cub Carburator Adjustment

Postby Glen » Sat Mar 03, 2018 9:26 pm

Hi,
Below is a page from the Cub service manual showing the timing marks.
A 1953 Cub probably has one timing mark on the front pulley. This manual is made for newer Cubs which have 2 marks. If you have one mark, it is number 1 in the pic, set the timing to that mark when the engine is running at slow idle speed, which should be 500 RPM.

With a Battery Ignition unit, the timing should advance as you speed up the engine, about to mark 2 at full speed, 1800 RPM.
They are talking about another subject on the page. The pic shows about the timing.

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

You have to loosen the 2 holders on the round part of the distributor base to turn the distributor, to change the timing. One bolt is on the engine side, behind the distributor, a box end wrench behind the distributor will turn the bolt, a little at a time.

My first post on page 2 of this post tells how to use a timing light some. There should be instructions with the timing light, if it is new. :)

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farmergiffIV
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1953 FCub
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Re: Cub Carburator Adjustment

Postby farmergiffIV » Sun Mar 04, 2018 11:37 pm

Eugene wrote:https://www.youtube.com/watch?v=c5gg4N7TguM&list=PLkIdYUEu9wunfBjz94D8kdqLwV8fahxjf&index=4

Wrenching with Rachael is usually very informative.


The video was helpful but I was sad she didn't pull out a timing light at the end and fine tune the timing. She said just play with the distributor slightly while engine running until it sounds just right and tighten it down there... hmmmm
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My '53 and '48 Cub Project

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farmergiffIV
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Joined: Sat Aug 17, 2013 8:36 pm
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Tractors Owned: 1948 FCub
1953 FCub
Location: Oregon

Re: Cub Carburator Adjustment

Postby farmergiffIV » Sun Mar 04, 2018 11:40 pm

Glen wrote:Hi,
Below is a page from the Cub service manual showing the timing marks.
A 1953 Cub probably has one timing mark on the front pulley. This manual is made for newer Cubs which have 2 marks. If you have one mark, it is number 1 in the pic, set the timing to that mark when the engine is running at slow idle speed, which should be 500 RPM.

With a Battery Ignition unit, the timing should advance as you speed up the engine, about to mark 2 at full speed, 1800 RPM.
They are talking about another subject on the page. The pic shows about the timing.

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

You have to loosen the 2 holders on the round part of the distributor base to turn the distributor, to change the timing. One bolt is on the engine side, behind the distributor, a box end wrench behind the distributor will turn the bolt, a little at a time.

My first post on page 2 of this post tells how to use a timing light some. There should be instructions with the timing light, if it is new. :)


Thanks Glen, I'll play with the timing light some and read the directions. I'm sure this and the valve tune up will make the engine run a bit more clean.

From the videos I did watch my understanding is: basically you run the enigne at lower RPM and then at higher and compare the two numbers or information the timing light provides which somehow allows you to fine tune the finall placement of the distrubutor. I
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My '53 and '48 Cub Project

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Glen
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Re: Cub Carburator Adjustment

Postby Glen » Mon Mar 05, 2018 6:43 pm

Hi,
Set the timing at the low idle speed, aligned with mark 1, like I wrote above. That is when you set it, by turning the distributor, then tighten the 2 hold down bolts again.

The only reason to check it at higher speeds is to see if the advance mechanism is working right. The advance improves the power of the engine at mid, and higher speeds. You don't compare anything to set the timing. Only set the timing at the low speed, then you are done setting it. :)

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farmergiffIV
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1953 FCub
Location: Oregon

Re: Cub Carburator Adjustment

Postby farmergiffIV » Mon Mar 05, 2018 10:06 pm

Glen wrote:Hi,
Set the timing at the low idle speed, aligned with mark 1, like I wrote above. That is when you set it, by turning the distributor, then tighten the 2 hold down bolts again.

The only reason to check it at higher speeds is to see if the advance mechanism is working right. The advance improves the power of the engine at mid, and higher speeds. You don't compare anything to set the timing. Only set the timing at the low speed, then you are done setting it. :)


Thanks for the clarification. I will hopefully get to try this soon!
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My '53 and '48 Cub Project


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