Two piece Automatic Spark Advance cam installation tip.

[953 nut 55,325]

If you are rebuilding an older model Kohler engine  with the two piece ASA (Automatic Spark Advance) camshaft you may feel like it is an imposable task. Unlike the ACR (Automatic Compression Release) cam the ASA cam is a two piece unit and none of the manuals I've read give you any guidance on their installation. 

 

The portion of the camshaft that operates the valves and fuel pump is separate from the portion that opens the ignition points. There is a pair of flyweights and associated springs on the cam gear that will advance the ignition timing once the engine comes up to speed. The gear and the ignition actuator cam have markings so you won't put it together 180 out. (see first picture) The ignition cam slips over the two flyweights and the small springs ride on the outside. So far so good. Now comes the tricky part, sliding the cam into place without dislodging the ignition cam. I have found that a 7/16" drill bit is just right for the job. You slip the drill bit into the hallow camshaft assembly, lower it into place. As you push the shaft your cam rides on into place it pushes the drill bit out the other end and both pieces are where they belong.

 

 

There are a couple ways to determine what camshaft you have. Presuming the camshaft in your engine is the one it was born with the data plate on the engine has a suffix that can tell you what camshaft was used. The table below will tell you the suffix applicable to your engine. The other way to determine what camshaft you have is to remove the cam gear cover and take a look. If you see a mechanism attached to the cam gear it is the ACR cam.

 

 

The following engines have the spark advance camshaft;

K-141, Suffix prior to “C”

K-161, Suffix prior to “J”

K-181, Suffix prior to “D”

K-241, Suffix prior to “D”

[squonk 41,162]

Remember small blocks don't have the gear cover. Suffix "A" K181's have the 2 piece cam. Suffix D has the 1 piece.

[Handy Don 12,237]

8 minutes ago, squonk said:

Remember small blocks don't have the gear cover. Suffix "A" K181's have the 2 piece cam. Suffix D has the 1 piece.

You answered the question that was on the tip of my tongue--what cam gear cover?! Thanks.

My Spec 30108A, then, has the two-piece actuator for the points cam advance. Good to know. Today did a static points setting and .020 has the points opening at just 1 or 2 degrees before TDC according to the T mark on the flywheel. Should I be dropping this to .018 or .019 to retard the timing slightly?

[squonk 41,162]

Run  it. You can always tweak it if you want.

[WHX?? 48,833]

Funny you should bring this up 'Nut. The other day I was reading the manual when Dan was building his motor and I read where the ASA cam has marks that must be lined up. This I did not know and musta got blind outhouse lucky when I built the 1055 motor. What would happen if you had it 180 out? 

We then static timed @Achto ACR motor and just for grins the points were gapped at a tight 017. 

Edited April 1, 2022 by WHX??

[953 nut 55,325]

10 hours ago, Handy Don said:

You answered the question that was on the tip of my tongue--what cam gear cover?! Thanks.

My Spec 30108A, then, has the two-piece actuator for the points cam advance. Good to know. Today did a static points setting and .020 has the points opening at just 1 or 2 degrees before TDC according to the T mark on the flywheel. Should I be dropping this to .018 or .019 to retard the timing slightly?

Ignition timing on Kohler engines.

 

Gapping the ignition points at .020 has always been the standard answer to how points should be set. That probably will get you into the ballpark where the engine will run, but with a bit of additional effort you can improve the engine’s power and performance.

The Kohler engine manual in the Red Square files section covers two methods for setting the ignition timing, Static Timing and using a Timing Light. This manual is a relatively new manual and it overlooks the fact that many of our engines were built prior to the ACR (automatic compression release) camshaft.

Earlier engines (mostly 1965 and earlier) had a Spark Advance camshaft that can not be timed using Static timing. At rest (and very low RPMs) the timing is retarded to fire slightly after TDC. The timing mark (SP) on your flywheel is at twenty degrees before top dead center but at rest the points on these engines break about ten degrees after top dead center. The only reliable way to check or set the timing on these engines is with a timing light.

There are a couple ways to determine what camshaft you have. Presuming the camshaft in your engine is the one it was born with the data plate on the engine has a suffix that can tell you what camshaft was used. The table below will tell you the suffix applicable to your engine. The other way to determine what camshaft you have is to remove the cam gear cover and take a look. If you see a mechanism attached to the cam gear it is the ACR cam.

 

 

The following engines have the spark advance camshaft;

K-141, Suffix prior to “C”

K-161, Suffix prior to “J”

K-181, Suffix prior to “D”

K-241, Suffix prior to “D”

[953 nut 55,325]

9 hours ago, WHX?? said:

Funny you should bring this up 'Nut. The other day I was reading the manual when Dan was building his motor and I read where the ASA cam has marks that must be lined up. This I did not know and musta got blind outhouse lucky (lucky is better than good in many cases)when I built the 1055 motor. What would happen if you had it 180 out? (spark would bee 180 out too)

We then static timed Dan's ACR motor and just for grins the points were gapped at a tight 017. 

For static timing I prefer to use a 12 volt test light. Watching the a change in the meter face while turning the engine allows for a slight delay, a light going out is instantaneous and your reaction to it will be faster in my opinion. 

[WHX?? 48,833]

3 hours ago, 953 nut said:

I prefer to use a 12 volt test light.

We used a DMM with a beeper which seemed to work good.  Dan was not happy 'till it was spot on! Biggest problem was the points moving oh so slightly  when tightening down. Prolly have an old skool timing light some where yet just for grins. 

 

3 hours ago, 953 nut said:

That probably will get you into the ballpark where the engine will run, but with a bit of additional effort you can improve the engine’s power and performance.

I always just set to 020 and called it a day. But I agree with the above. Seems like K91s in particular like to start easier when tweaked. 

 

Edited April 1, 2022 by WHX??

[Handy Don 12,237]

4 hours ago, 953 nut said:

The timing mark (SP) on your flywheel is at twenty degrees before top dead center but at rest the points on these engines break about ten degrees after top dead center. The only reliable way to check or set the timing on these engines is with a timing light.

 

Now I have to go look to see if my K181 with "A" spec has an SP mark for the spark advance target while running. THEN, I have to see if I can find my old timing light--which I haven't used since I sold my VW Beetle in 1980 as all my cars after that had electronic ignition! I'm assuming that the spark advances as the engine reaches idle speed, correct?  

 

I static-checked the timing with a DMM beeper, as did @WHX??, just as a confirmation after setting the points. Assuming the SA (spark advance) cam at rest is in its "not advanced" state, I should be seeing the points open after TDC, i.e. a bit after the "T" mark, and not slightly before as now. Hmmmm. 

 

Anyway, this is all academic until I put the engine back together and try to start it! 

 

Thanks @953 nut and others.

Edited April 1, 2022 by Handy Don

[Achto 27,609]

9 hours ago, Handy Don said:

Assuming the SA (spark advance) cam at rest is in its "not advanced" state, I should be seeing the points open after TDC, i.e. a bit after the "T" mark, and not slightly before as now. Hmmmm. 

 

If you have an ACR cam, the points should just break when the "S" mark is centered in the hole. This would be the correct static timing. The S is the advance and should appear before the "T" mark

[Handy Don 12,237]

7 minutes ago, Achto said:

 

If you have an ACR cam, the points should just break when the "S" mark is centered in the hole. This would be the correct static timing. The S is the advance and should appear before the "T" mark

Thanks, @Achto, for confirming my thinking (you did mean a Spark Advance cam, right?). I found the S mark on the flywheel and I'll now reset the points to "stop buzzing" the DMM right there! 👍

So far, I haven't found my timing light--I think I donated it to some organization about 20 years ago assuming I'd never use it again!

Edited April 2, 2022 by Handy Don

[Achto 27,609]

4 minutes ago, Handy Don said:

(you did mean a Spark Advance cam, right?)

 

No I did mean an ACR cam. @953 nut explained that static timing will not work on a spark advance cam.

[Handy Don 12,237]

1 minute ago, Achto said:

 

No I did mean an ACR cam. @953 nut explained that static timing will not work on a spark advance cam.

Yikes.

Yes, now rethinking and I'm not sure I agree with @953 nut that it won't work.

It seems that when at rest, the SA cam should static time at the "retard" position for easier starting--right around TDC, i.e. the T mark (this is what I did today). Once running, the cam advances the spark for more power, so it should dynamic time at the S mark, a few degrees before TDC. So a timing light would still be handy to tweak it once it's running. I agree that static timing cannot be quite as precise as dynamic, but it should be very close.

[Achto 27,609]

Just for an example: I have a K91 that was was a major PITA to start, warm or cold. The points were set at .020". A K91 has a basic cam, no ACR or spark advance. I static timed the engine and the points gap ended up at .018". This engine now starts on 1 or 2 pulls without fail.

[Handy Don 12,237]

9 minutes ago, Achto said:

Just for an example: I have a K91 that was was a major PITA to start, warm or cold. The points were set at .020". A K91 has a basic cam, no ACR or spark advance. I static timed the engine and the points gap ended up at .018". This engine now starts on 1 or 2 pulls without fail.

Decreasing the point gap retards the spark because the points open later, so your change makes perfect sense.

 

Without ACR or SA, it is always a compromise between ease of starting and maximum efficient power output. I'm sure you've seen older cars and trucks that had manual spark advance controls so they could be tuned on the fly based on the quality and octane of the fuel, the engine temperature, and other factors. Typically, they "rotated" the distributor body holding the points a few degree relative to the points actuating cam.

The issue with the SA cam is that it isn't a precise movement. Those little fingers on the weight arms pushing on those little holes in the cam have some slack and can wear. Hence, yes, the most precise way to set the timing is by timing light.