Issue: Can’t get the idle/max timing set.

[swdockter]

I can’t get the idle timing set at 5-8 atdc. It’s around 13-15. I also can’t get the timing set to 27 on the max side. When I use the process from clams or laddies, I see the results I’m looking for but not in the water. I don;t get it. I’m using the same timing light? I also went through the manual and set to the .464 setting. I have not adjusted the carbs but have noticed the bottom carb adjustment is out much further than the top. Should I start there and readjust the idle speed and go from there?<br /><br />And, I have no tack on this boat. Is there another way to get the RPMs. The boat is a 86 4 cyl 75 hp. fully rebuild, just going through break in period now.

 

[timmathis]

Re: Issue: Can’t get the idle/max timing set.

Are you sure you have it at TDC?

 

[swdockter]

Re: Issue: Can’t get the idle/max timing set.

Tim, I think I do or dam close. I checked 0 at the flywheel and the .464 offset on the flywheel as well. The Merc manual has this instruction set and the .464 mark is on the flywheel so I checked that. <br /><br />I can't figure out why the degrees are so different in the water. when I take #2-4 plugs out and dry run it, if you will, if measures out.

 

[timmathis]

Re: Issue: Can’t get the idle/max timing set.

For some reason it must not be fully advanceing With just your starter? This is one for clams! And on the air screws they should be close to the same. I would readjust. But that shouldn't have anything to do with your timing. What do you get on the max side?

 

[swdockter]

Re: Issue: Can’t get the idle/max timing set.

Tim, On Laddies or Clams sync and timing process (dry run) with all but plug #1 out. <br /><br />I get very close to 27 btdc. On the water it looks like about 10-15 btdc. it's weird and I have no idea. I will get the boat back in the water this weekend (family vacation) so I'll try her again. I'd like to have some ideas so I don;t ruin the family vacation =)<br /><br />I really have a good feel for the process described by laddies or clams, it's very straight forward. The only thing I can think of is the idle is so off, because excess breakin oil and carbs off that I cannot get enough idle timing set in the timing arm. the timing arm is very very close to the throttle arm.

 

[timmathis]

Re: Issue: Can’t get the idle/max timing set.

Im not sure eather. I would hate guess at this one. because if you over time it it will kill you! HELP CLAMS where are you?!!! <br />Sorry I was no help. Tim

 

[Clams Canino]

Re: Issue: Can’t get the idle/max timing set.

I cant see why 27 on land would turn into 15 on the water. Something is just plain fishy here. Is the belt on right? You can run it as long as you're sure it's not too advanced. OH!!! And where are you getting 27 from???? The max advance spec is 21 and no more.<br /><br />-W

 

[swdockter]

Re: Issue: Can’t get the idle/max timing set.

Calms, <br /><br />The merc manual states 27 btdc . Before I touched anything, and followed the sync process, I was getting like 22-26 range. So I knew it was within spec???? At least I thought. The light I have clips on over the spark plug wire so maybe it's not giving me the best results...I don’t know. I do know that it is a bit jumpy, meaning it will hunt all over like 22-26 range. Not sure why it's not more consistent other than maybe I'm not holding the timing lever still enough...who knows. I'm going to get her back on the water and tweak the timing again and then head right to the carbs. And then back to the timing and get this thing running right. <br /><br />By the way, I have the thing idling nice but when I drop it in gear, she falls on her face which tells me the timing is too retarded....hell, maybe that’s my problem too <br /><br />You know, I love working on my snowmobile motors, these are much different animals – WOW.

 

[timmathis]

Re: Issue: Can’t get the idle/max timing set.

Clams talking about ATDC not BTDC 21 max!!!<br />wazzzup -W

 

[timmathis]

Re: Issue: Can’t get the idle/max timing set.

I think you have your btdc and your atdc mixed up! you had better recheck your specs,manual and or light.

 

[Clams Canino]

Re: Issue: Can’t get the idle/max timing set.

To clear this up, if you disconnect the throttle cable and use a tie wrap to hold it at WIDE OPEN and then spin the motor with a timing light on #1 - it outta read no more than 21 degrees. It's a VERY old manual that says 27, Mercury long ago revised the spec to 23 and then soon after settled on 21 into perpetuity. Not heeding this will result in melted pistons.<br /><br />-W

 

[swdockter]

Re: Issue: Can’t get the idle/max timing set.

Clams, I sure am glad I found this site. Knowing me, I would have been filing the stud off to get to 27 degrees. I will goto 21 for a max so I don't end up with a piston paper weight. I'll let you know how things go after I re-follow your directions again.

 

[swdockter]

Re: Issue: Can’t get the idle/max timing set.

OK, here is my follow up. <br /><br />This process, of course, is perfect. I on the other hand, am in the learning process. After doing the process more the 4 times to get it perfect, I found that adjusting the carbs was the most time consuming thing for my motor. <br /><br />Throw in two stupid situations that caused me to go in circles which I’ll mention just for the other newbies like myself. 1) I had taken out the spark plugs and looked at them to see if they were ok and not fouled. They were fine and put them back in. Well, I always caution on the light side when putting plugs back in and one worked it’s way loose…evident by the “blow by” oil around the plug…that cause me some missed readings and diagnoses. 2) My fuel ball goes limp almost 5-10 minutes after resting. I missed that a few times which caused me to scratch my head and turn some screws. <br /><br />If I had not missed the two items above, it would have taken me an hour or two to dial the thing in. Instead it took me a couple more hours but I’m glad to say the motor is running like a charm. <br /><br />The only weird issue I have it the bottom and top carbs are not set at the same setting. The motor stumbling routine was followed multiple times and it runs best with the top one about 1.5 turns while the bottom is more like 2.25-2.5 turns out. Not sure what that means. Probably the upper carb needing to be rebuilt.