Possible Crank/Cam gear Timing Issue C-113

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arlen
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Possible Crank/Cam gear Timing Issue C-113

Postby arlen » Sun Apr 04, 2021 1:07 am

Well, I'm mildly panicking...hopefully for nothing.
It seemed fairly obvious to line my cam gear up with the punch on the crankshaft gear. I noticed at the time that #1 was not at TDC, but a few deg past TDC on the intake stroke. I thought it strange, but I haven't worked on one of these before.
There was a clear single punch on the crank gear, and a clear single punch on the cam gear, and a double punch on the cam gear 180 deg from the single punch. I checked, double checked and went on my merry way and installed the front cover and pulley.
Then I was watching a Youtube video from the Canadian Redneck and he casually mentioned that when you time the governor to the cam by lining up the double punches that #1 will be at TDC at that point. He didn't specify if it was compression of exhaust stroke.
Mine is not that way. I was hoping if someone can confirm if it truly is at TDC when the marks are all in line. And could you confirm if compression or exhaust.


Here is a picture of the governor gear lined up with the double punch on the cam gear. Here #1 is a few deg past TDC on the intake stroke.
Gear pic 1.jpeg



Here is a pic of the mark that I lined up with the crank punch mark. Here #1 is a few deg past TDC on power stroke. The marks are a little puzzling here, but that big mark is 180 from the very clear double mark of the 1st picture. There are actually 4 marks here on the cam gear if you look close!
I hope I am just confused.
I should note that the crank was not the original, but the Cam and governor are the originals.
Gear Pic 2.jpeg

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby Jim Becker » Sun Apr 04, 2021 12:28 pm

What is a few degrees? Something like 2 or 3, or more like 11?
When set at TDC, what is the angle of the magneto drive slot?
What are all the punch marks on the can gear? I see one that is double-struck that you are using and another single mark one tooth over. Is this what you found when you took it apart?

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby arlen » Sun Apr 04, 2021 2:19 pm

Jim Becker wrote:What is a few degrees? Something like 2 or 3, or more like 11?
When set at TDC, what is the angle of the magneto drive slot?
What are all the punch marks on the can gear? I see one that is double-struck that you are using and another single mark one tooth over. Is this what you found when you took it apart?

Thanks for responding , and happy Easter!

It absolutely could be 11 deg, which is one tooth.(the piston in down about 1/8 it 3/16 after TDC when the marks are aligned)
I will look at the angle of the drive slot and report back.

That whole mess of marks is rather confusing. I do know that the double struck mark that I lined up with the crank gear is 180 deg out from the double punch that I Iined up with the double punch on the governor gear.
When I took it apart I was unable to get the pulley or the front cover off, I just got a reground crank. so I don’t know which mark was lined up on the original crank, as it was hidden behind the front cover. I was able to see the mark on the original crank after the fact, and there is just 1 mark.


I don’t have the head on yet, so I dropped the push rods for 1&4 in the block. When #1 is at TDC compression, #4 intake push rod starts moving pretty much right at TDC. I’m wondering if it should be more like 11deg BTDC, but I don’t know for sure.
I was hoping someone could tell me if #1 should be at TDC when the marks are all aligned, and whether it should be compression stroke or exhaust.
Mine is currently after TDC on the intake stroke.

If I have to pull the pulley/front cover off, it’s not the end of the world. I will be cussing myself for using the aviation Permatex on the gasket though!
The only reason I put it on at this stage is that it’s so much easier to turn the engine over with the hand crank.

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby Jim Becker » Sun Apr 04, 2021 8:06 pm

This is what I think, but not sure as I haven't seen it documented:
With the crankshaft at #1 TDC, the single punch mark on the crank gear will be in position to time the camshaft.
The camshaft needs to be installed with the single punch mark in line with the one on the crank gear. This positions the camshaft for #1 TDC on compression.
With the camshaft thus positioned, the double mark on the cam gear will be in position to time the governor gear. The double mark is NOT exactly 180 degrees from the single mark.
When the governor is installed with its double punch mark in line with the double punch mark of the cam gear, the magneto/distributor drive slot will be 35 degrees from horizontal.

What I suspect:
The double struck mark on your cam gear was added by some PO. The real single mark is the one on the adjacent tooth.
You have the cam gear one tooth off.
When you position your crankshaft at TDC, your distributor drive slot will be off, confirming that SOMETHING is not timed right.

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby tst » Sun Apr 04, 2021 8:28 pm

TDC is when #1 piston at the top of the block, the exhaust valve is closing and the intake starting to open, many times the key on the crank will be at 12 oclock spot also for TDC
Last edited by tst on Sun Apr 04, 2021 8:31 pm, edited 1 time in total.

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby arlen » Sun Apr 04, 2021 8:30 pm

If I move it over 1 tooth, I will still be out 180 as currently the marks as I have them lined up now puts me after TDC on intake.
I guess I will have to try every combination until I can get it lined up at TDC on compression.
I see that there are methods for definitively checking the timing, but i will have to have the head on and flywheel and mated to the tractor. I will definitely be verifying all of that before I put the front cover back on!

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby arlen » Sun Apr 04, 2021 8:32 pm

tst wrote:TDC is when #1 piston at the top of the block, the exhaust valve is closing and the intake starting to open

Ok that would make sense if I’m a tooth off then. You’re saying that when the marks are aligned, I should be at the end of the exhaust stroke, not compression stoke. Thanks!
And yes, on mine the key is at 12:00 at TDC

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby Jim Becker » Sun Apr 04, 2021 8:34 pm

Turn your crankshaft349 degrees to TDC. Then move the camshaft one tooth.

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby arlen » Sun Apr 04, 2021 9:17 pm

Jim Becker wrote:Turn your crankshaft349 degrees to TDC. Then move the camshaft one tooth.

Thank you for our help!

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby arlen » Tue Apr 06, 2021 8:45 am

Jim Becker wrote:Turn your crankshaft349 degrees to TDC. Then move the camshaft one tooth.


That appears to make matters worse.
Based on what you have said...
1) #1 should be at TDC when marks are in mesh on crank/cam
2) Governor timing mark on cam is NOT 180 deg from crank timing mark on cam
I looked at all the images and videos that I could find on the net, and found another constant--When the crank marks are in alignment, the cam keyway is ALWAYS pointed to the left, which means that #1 is on compression stroke.

So that establishes the half circle that I need to be on.

Here are a couple pictures now that I got the front cover off again. 1st pick is how I had it together. You can see that the cam key is pointed to the right. In my mind, that eliminates all of those marks on that half of the gear. Which leaves only the set of double marks as the possibility. BUT...you can see that the crank still has to rotate before the gears are in mesh.
It seems like the timing mark on the crank is off 1 tooth.
Maybe someone has a gear laying around and can check the marks. Mine has the mark on the 5th full groove from the key.
If not, I will take my original crank to a machine shop and have them extract the gear so I can look at it.

Second picture meets all of the criteria, making the assumption that the crank is off by 1 tooth.

I know its allot to digest, but what are your thoughts at this point?

Timing Gear 2 - Copy.jpeg


Timing Gear1 - Copy.jpeg

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby tst » Tue Apr 06, 2021 9:42 am

forget about the marks for a moment, you said the head is off, turn the crank so #1 piston is on top, then install the cam so that the #1 intake is just starting to open while the #1 exhaust valve is closing, then see where your marks are

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby Jim Becker » Tue Apr 06, 2021 9:59 am

I can't see the marks in the pictures well enough to tell anything. It looks to me like the crank/cam is now 2 teeth off and the cam/governor is 1 off. I don't think the double struck mark is an original mark. Decide what is real. Then align the single mark between two teeth of the crank gear with a single mark on a tooth of the cam gear. Then align the double mark between two governor teeth with the double mark on a tooth of the cam gear.

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby arlen » Tue Apr 06, 2021 10:11 am

tst wrote:forget about the marks for a moment, you said the head is off, turn the crank so #1 piston is on top, then install the cam so that the #1 intake is just starting to open while the #1 exhaust valve is closing, then see where your marks are

Well, I've kinda done that... That's my first picture in the previous post
The questions that presents are:
1)the cam keyway should be pointing to the left (based on all images that I could find)when the cam is in the right spot, which means 1# is on compression not intake.
2) According to the service manual, the intake should open at 15 deg after TDC Does that mean it starts opening at at TDC?

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby arlen » Tue Apr 06, 2021 10:16 am

Jim Becker wrote:I can't see the marks in the pictures well enough to tell anything. It looks to me like the crank/cam is now 2 teeth off and the cam/governor is 1 off. I don't think the double struck mark is an original mark. Decide what is real. Then align the single mark between two teeth of the crank gear with a single mark on a tooth of the cam gear. Then align the double mark between two governor teeth with the double mark on a tooth of the cam gear.

If we get rid of the double struck mark, then I'm left with two sets of double marks --no single mark to work with. If we make the assumption that the cam key has to point to the left, then there is only the one double mark on that half. Then the other double mark lines up with the governor nicely.
But only if the crank mark is one tooth off.
Apparently no one has a crank gear laying around to look at :D

Zoom in on my second picture

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Re: Possible Crank/Cam gear Timing Issue C-113

Postby Jim Becker » Tue Apr 06, 2021 10:29 am

I've clicked, zoomed, squinted at all four pictures. I suspect the marked tooth next to the double struck tooth was originally the single marked tooth. There really isn't anything else I can add.


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