2005 Mercury 60 Throttle Cam alignment

[litespeed]

Engine is a 2005 Mercury 60hp ELPTO. Oil injection has been removed and it's running premix. I recently had this engine rebuilt and it was not running right. So, I broke out the Mercury manual (online) and proceeded to follow the steps to try and sort it out before contacting the re-builder.

After checking the timing (at cranking speed) and some time on the water making minor adjustments, I finally got it to where it is running pretty decent again.

Problem was very bad idle, stumble or sputter off idle, vibration from 1200 to 1900RPM and stumble or hard miss around 2800 RPM before smoothing out around 3000 RPM. 3000 to WOT smooth and normal.

Most of the issues were from improper carb sync., idle mixture adjustment and excessive gap between the cam follower and throttle cam.

At this point all of the above issues have pretty much been resolved except a very slight vibration still between around 1300 and 1700RPM.

OK.... So, here's the question. In the manual it states that the center of the cam follower should line up with the hash mark on the throttle cam for the initial alignment before adjustments. Now after everything is adjusted and set, the hash mark on the the throttle cam is about 1/8" higher than the center of the cam follower. Is this a problem and something that I should revisit? Or is it good and just leave it alone?

As it is now with the engine running, timing at idle is 2 to 3 ATDC and idle in gear is around 675 RPM. Cam follower gap is on the tighter side of the .005 to .040 spec. I had to play with the cam follower gap adjustment and idle mixture quite a bit to get rid of the "off idle stumble". I had a hell of a time getting the idle mixture just right. I always tried to err on the richer side and then wound up having to lean it out a bit to get rid of the stumble.

Any input or insight to any of the above greatly appreciated. Pic of throttle cam and cam follower below.

[Dave S]

you are off....The cam roller is not right. Un screw the bottom most screw on the throtel arm till the slash lines up with the roller. lossen the screw just under the roller. Adj the lower screw again to the roller. The engine speed is done by the small screw just above the pivit point on the arm.The roller should be 1/6 away from the cam. at idle. You will have adj the cables after this setting....

[litespeed]

Thanks for the reply! That's what I thought... The problem is that when I loosen that screw and move the cam follower roller "back" so that the hash marks line up with the throttle cam, I need to adjust the idle timing screw too much to close that gap. Does that make sense? Then the idle is off.

Perhaps I need to adjust the bottom of the linkage somewhere to change that gap and then reset the idle timing to 0 and the max. timing to 22 and just start over again?

I'm out of town until next week now. I'll start over from scratch when I get back in town and report back the results. Here is the directions I'm following. Maybe I did something out of order?

[Dave S]

When you adjust the arm.... you have to readjust the cam roller. there is a philips screw just under the roller that will set the 1/6 gap.

[litespeed]

I made it back early so I was able to tinker around with this late this afternoon. I think I figured out the problem. The problem was the "idle stop screw" was in too far. That is the screw in the bottom of the big picture below (you can only see part of the screw in the pic). I screwed that screw in about 1/4" and it got the throttle cam to line up perfectly with the cam follower. I then re-adjusted the gap between the cam follower and throttle cam. I was not able to run the boat in the water yet. But, I did manage to adjust the "idle timing screw" to get the out of water idle back to about where it was before. I'll do the rest of the adjustments in the water tomorrow.

The only issue I can think of now is that when I backed off that "idle stop screw", it moved the entire arm back quite a bit. So, is it safe to say, I should recheck the Max. Timing @ cranking speed again?

Thanks for the input on this. Big pic shows the entire linkage as it is now and the little pic shows the alignment now between the cam follower and throttle cam. Big difference... At idle on the muffs is 800RPM and 2 degrees ATDC.

[litespeed]

I finally got it out on the water... That was the ticket! She romps right out of the water now. I have never been able to "slam the throttle forward" without some kind of stumble or hiccup before. It leaps onto plane immediately and is very smooth across the board all the way to WOT. Still a little vibration between 1400 to 1700RPM though? This could not be idle mixture right? Possibly the carb sync is still off a tad? Would carb sync being off cause a vibration in a narrow RPM range like that? Still light years different than before.

Again, the key was getting the cam follower gap as tight as possible. Any gap at all between the cam follower and throttle cam would cause a stumble and vibration.