K301 will not 'take' any ignition timing

[Greentored 3,201]

I'm stumped here fellas, calling on the Kohler heads! My 1277 'lawn duty' absolutely, positively will not 'take' any more than 4-5 degrees of timing without rattling its guts out. 

Tractor and engine history unknown, but i've used it all summer, the oil is still clean, and it hasnt used more than 4-5 ounces of oil.

Engine is in a proper state of tune, appears to have been a recent overhaul, and is .030 over. New Kohler points and condenser. Ignition timing set with ohm meter. Timing marks verified at true TDC and marked on shroud with a sharpie for ease of adjustment. Engine would take no more than TDC-2 degrees.

Yesterday, I Decarbon'd head and chamber, did a valve adjustment, and put it on 93 octane. Set it at 20 and fired up- it sounds strong and smoothe, but spark knocks at 1/2- open throttle like crazy! I actually fired it up and used a screwdriver to slowly close the point gap while it's running, until smoothe. When I get to a point that the spark knock goes away, the engine tone changes from smoothe and it tune to labored, like its fighting itself to stay running. Afterward, timing check- 4-5 degrees BTDC. That is all this thing will take!

It runs and cuts, but there is certainly a reduction in power.

Any ideas where to start?

 

[Greentored 3,201]

An interesting side note:  When I pulled the breather cover to lash the valves, oil POURED out. I stuck a wire in the oil drain hole and it appears it was never drilled completely through! Yes the piston was at TDC, so was not in the way. This will have to be addressed over the winter, as Im not about to punch a hole through to the bottom of a cylinder without chamfering and getting the shavings out.  Its been this way since 1967, it should make it another 2 months

Anyone ever seen anything like that?

[JoeM 7,871]

to lean? not enough fuel? 

exhaust restriction?

just thinking

[Greentored 3,201]

4 minutes ago, JoeM said:

to lean? not enough fuel? 

exhaust restriction?

just thinking

Carb seems to adjust itself out correctly so I think the air/fuel is correct. It DOES have some play in the throttle shaft, I can watch it 'pulse' when idling.

Have had 3-4 different exhausts on it, from restricted to open. No change.

[Achto 27,505]

If you are setting the timing with an ohm meter, the "S" mark not the "TDC" mark on the fly wheel should be centered in the hole in the shroud when the points just open or loose continuity.

 

Kohler static_timing.pdf

 

If it runs worse at higher RPM's I would also suggest trying a different condenser. Also make sure that the condenser body has a good ground. 

 

One more thing, check to see that you have the proper coil. Your coil should have an internal resistor. This should be written on the coil. If it is an external resistor coil, it will give you some of the symptoms that you speak of.

Edited September 14, 2020 by Achto

[ebinmaine 67,277]

[Greentored 3,201]

1 hour ago, Achto said:

If you are setting the timing with an ohm meter, the "S" mark not the "TDC" mark on the fly wheel should be centered in the hole in the shroud when the points just open or loose continuity.

 

Kohler static_timing.pdf 1.7 MB · 3 downloads

 

If it runs worse at higher RPM's I would also suggest trying a different condenser. Also make sure that the condenser body has a good ground. 

 

One more thing, check to see that you have the proper coil. Your coil should have an internal resistor. This should be written on the coil. If it is an external resistor coil, it will give you some of the symptoms that you speak of.

The static timing link you posted is exactly how I'm doing it  History on coil is unknown, but it IS a Delco, most likely off an automobile. I have a Kohlers under the bench, will try a known good coil and condenser and see what happens.

Appreciate it!

[oldredrider 2,548]

Just a thought...since you mentioned a rebuild, is the crank timed properly to the cam? 

[Tractorhead 9,064]

Did you checked the keeway?

maybe flywheel is out of timing.

 

[rmaynard 15,427]

I have found myself making the mistake of rotating the flywheel in the wrong direction when doing the static timing. It will get you every time.

 

As far as the air leaking around the throttle shaft, that will make the engine run lean and simulate other problems. If you don't have a throttle bushing kit, you can remove the throttle shaft and put a thin nylon washer  or o-ring between the top of the carburetor and the underside of the plate on the shaft. If it's the right thickness, and snug around the shaft, it will still let the shaft move freely, but will restrict the air that is being pulled in around the shaft.

[ebinmaine 67,277]

25 minutes ago, rmaynard said:

put a ********* between the top of the carburetor and the underside of the plate

 

Bob is this one of the carbs that would use the oillite bushings?

[rmaynard 15,427]

Yes. I used to have a bunch of those bushings, but when I went to rebuild a #26 carburetor a couple of years ago, I was out. I found a 1/4 ID o-ring that was about 1/32" thick. It fit and compressed enough to get the throttle plate screwed on. It sealed the shaft and is still on the carburetor today.

[ebinmaine 67,277]

2 minutes ago, rmaynard said:

a 1/4 ID o-ring

That's good information. Thank you.

 

Scott if you need the part number for those oillite bushings or want some, let me know.

[rmaynard 15,427]

It may not have been 1/4", but it fit snug on the 1/4" shaft.

[Bill D 1,907]

I vote for new points, condenser, proper Kohler coil.  Use a timing light to set the timing.  Bill

[Greentored 3,201]

@oldredrider That is something I haven't verified and makes sense- if its advanced a tooth, the compression would certainly be much higher than it should and maybe cause this.

@Tractorhead While the head was off, I used a sharpie and marked true TDC on the shroud, as well as a 20 degree mark.

@rmaynard @ebinmaine thanks guys! I certainly have the ability to fix these throttle shafts and would love to save a couple true Kohler carbs. If the oilite bushings are still available thatd be awesome, if not, maybe I could cut a small recess and shove an o ring in there.

 

Really appreciate the ideas fellas! Fortunately I have a couple good running engines under the bench, so I can do some parts swapping instead of throwing money away if it doesn't work. Will update with results.

 

[ebinmaine 67,277]

1 minute ago, Greentored said:

If the oilite bushings are still available thatd be awesome

They're just a standard part available right through McMaster Carr

[953 nut 55,077]

4 minutes ago, ebinmaine said:

They're just a standard part available right through McMaster Carr

If your throttle shaft has any side to side movement (more than a tiny tiny bit) you can put a bushing on the top of the carb to correct it. Kohler makes one part #2515802-5,  7/16" o.d. x 1/4" i.d. x 1/8" thick but I have never found it in stock at Partstree or other online parts places (you might find it on ebay).    If you have a hardware store with all those little parts drawers you can get some brass thrust washers 7/16" o.d. x 1/4" i.d. x 1/16" thick Hillman part #58087 or McMaster-Carr part # 5906K561and stack 2 of them in that little recess in the top of the carb body. 

[Greentored 3,201]

Update: swapped a coil and condenser off a known good runner and bumped the timing up a bunch. Although it rattled a touch after 20 minutes of hard mowing, it is a day and night difference! It’s never had the power it does now, and just runs ‘happier’. 

No doubt once I put a light on it and set correctly, she will be good to go, or at least a helluva lot better. Appreciate the help

guys!

now can someone fill me in on the coils with built in resistor? I’m aware of automotive engines running 8-9 volts at the coil, but never heard of the coil itself providing that reduced voltage. 

[ebinmaine 67,277]

Might have been for production ease or just the way some engineer designed them. Some vehicles have a built in resistor and some don't. 

[953 nut 55,077]

11 hours ago, Greentored said:

can someone fill me in on the coils with built in resistor?

VW used coils with a built in resistor beginning in 1967, prior to that all VW electrical systems were 6 volt and had no need for a resistor.

[Greentored 3,201]

2 minutes ago, 953 nut said:

VW used coils with a built in resistor beginning in 1967, prior to that all VW electrical systems were 6 volt and had no need for a resistor.

So, can we run VW coils on our horses? Or perhaps an OEM coil isnt too pricey?

Next thought would be an inline resistor on the + side and a standard 12v automotive coil?

[953 nut 55,077]

15 minutes ago, Greentored said:

So, can we run VW coils on our horses? Or perhaps an OEM coil isnt too pricey?

Next thought would be an inline resistor on the + side and a standard 12v automotive coil?

All of the above will work, VW coils are plentiful so that is what I buy.

[pfrederi 17,666]

Ballast resisters are widely available and cheap....BUT if they get wet they can fail...

[Achto 27,505]

1 hour ago, Greentored said:

So, can we run VW coils on our horses? Or perhaps an OEM coil isnt too pricey?

Next thought would be an inline resistor on the + side and a standard 12v automotive coil?

 

Tractor Supply or Napa normally carry 12v coils with an internal resistor for under $30. Most 12v automotive coils will work as long as they have an internal resistor. On a side note: when you buy the coil take it out of the package and make sure that it says internal resistor on the coil it's self. I have run into right package/wrong coil in the past.

 

Another source.

https://www.amazon.com/Ignition-Internal-Resistor-Universal-Voltage/dp/B00WMOB1ZU/ref=sr_1_2_sspa?dchild=1&keywords=12v+coil&qid=1600262944&sr=8-2-spons&psc=1&smid=A34668PDYO45KB&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFTOVlZTFkyN1BDWlAmZW5jcnlwdGVkSWQ9QTA1MjM3MDgxTFpYQTBFWkYyTUlZJmVuY3J5cHRlZEFkSWQ9QTAzNTM2NzAyUkVIU0hTQ1RBNzI1JndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==