Checking sync and link settings on 150hp carbed V6?

[hkeiner]

Is is possible (i.e., practical or reasonable) to check whether the sync and link settings described in the Mercury shop manual agree with the motor's actual setup without actually changing any settings on the motor.

I would like to do this to learn (or confirm my understanding of) the sync and link procedures/settings described in the Mercury shop manual before I actually try to do a sync and link. I have a Mercury 150HP V6 carbed outboard that runs pretty well but I plan to remove the carbs for cleaning (to possiblly improve the motors's idleing) as they have not been cleaned since the motor was new. I worry that I may mess up the sync and link by removing the carbs and not properly performing the sync and link afterwards because I don't understand the manual’s sync and link procedures well enough. I figure that checking the motor's current sync and link settings before carb removal would be a good hands-on lesson and also instill some confidence in my ability to do a proper sync and link after removing and cleaning the carbs. I don’t want to damage the motor by doing a sync and link improperly.

If all of the sync and link settings can not be checked this way, which ones can be checked and which ones can not be checked? Which settings have to be re-set after a carb removal and which ones wouId not be affected by a carb removal. For exampple, I figure that I can't check the carb's low speed jet settings before carb removal without moving the jets, so that may not be a setting that I can check without changing a setting.

Does this all make sense?

 

[Laddies]

Re: Checking sync and link settings on 150hp carbed V6?

If you don't tinker with any adjustment and simply R/R the carbs they don't need to be resycronized. You may also go thru a syn and link by the book and not do any adjustments to get the feel for it

 

[hkeiner]

Re: Checking sync and link settings on 150hp carbed V6?

That is what I will do. I'll check the sync and link settings before carb removal and if anything looks out of spec. or if I can't figure out how to check a particular setting., I can then decide what to do next (adjust, leave alone, ask more on this forum).

After reading the sync and link section of my Mercury manual with greater concentration, I appears that timing related linkage settings are not affected by carb removal. I wasn't so sure about the linkages that affect the carb. butterfly movement or the oil pump.

Thanks for the response.

 

[Silvertip]

Re: Checking sync and link settings on 150hp carbed V6?

Sure you can check jet settings. Before you remove carbs, get a pad of paper and pencil, and then one idle mixture screw at a time, turn the mixture inward, counting the turns as you go. When the mixture screw is lightly seated, note the number of turns and then back it out again exactly the same number of turns. You will now be able to disassemble, clean, and reassemble the carbs with new kits and reset the idle mixture screws exactly where they were. Very likely, all mixture screws will have slightly different settings. If you find one that is very different than the others, it was probably misadjusted to start with.

 

[j_martin]

Re: Checking sync and link settings on 150hp carbed V6?

Silvertip,
Could you tell me where the idle mixture screws are on Mercury V6 carbs?

 

[jrampey]

Re: Checking sync and link settings on 150hp carbed V6?

hkeiner - what year is your motor... not that it matters -none of the V-6 carbs have adjustable idle jets. They are all fixed orifices. Silvertip must be thinking of another engine.

 

[hkeiner]

Re: Checking sync and link settings on 150hp carbed V6?

It is a 1996 150hp V6 model (SN OG397853) with WMH carbs. In reading the shop manual, it appears that they distinguish the term "jet" for fixed jets and "screw" for adjustable jets. Now I am not sure if I am correct to use the term "jet" interchangeably with 'screws" causing some misunderstanding. Anyways, below is a listing of the jets/screws in the parts list for my carbs and I categorized them based upon my understanding of their adjustability.

Non-Adjustable:
- Off idle progression air jet
- Back draft vent jet
- Idle air jet
- High speed fuel jet

Adjustable:
- Fuel mixture adjustment screw (I think these are also called idle mixture screws, low idle jets, and similar.)
- Air calibration screw behind welch plugs (the manual says that these are factory set and that they should NOT be removed/adjusted for carb cleaning.)

 

[Silvertip]

Re: Checking sync and link settings on 150hp carbed V6?

Idle mixture screws are easily identifiable. They almost always have a small spring beheath the head of the screw to keep tension on them so they don't move. When you mentioined low-speed jet settings I just assumed you meant idle mixture screws. As was pointed out, many carbs have fixed jets so are not adjustable. Those are distinguished by the slot across the jet and the jet itself will have a hole in the center.

 

[j_martin]

Re: Checking sync and link settings on 150hp carbed V6?

hkeiner,
There are no mixture screws on that carb. There are 6 jets, 2 each of main, idle, and float chamber air. They interact, and of course each affects a different rpm and load range. To further complicate things, sometimes Mercury uses different jets in different bores on the same engine to compensate for some other mechanical difference.

If you make a mistake and cause a lean condition in one or more cylinders, you could do serious mechanical damage to the engine.

If the engine has been running well, I would freshen up the carbs, replacing the needles and seats, and paying attention to float adjustment and float condition. There isn't much else that can go wrong with them except maybe a sticky throttle shaft.

If your engine is running a little ragged at idle, has good compression, and you don't find anything obvious wrong with the carbs, I'd check the reeds before I buttoned it up.

There are folks that swap carbs, and mess with these engines to the nth degree. Most of them hang out on screamandfly.com. One in particular, who goes by the handle T-rex, indicating, I think just how long he's been messin' with things, could identify what you have and make recommendations about exactly what to do. Many others on the board could also, and jump in to help. If you post at screamandfly, they will ask detailed questions, and give you detailed answers.

hope it helps
John

 

[gss036]

Re: Checking sync and link settings on 150hp carbed V6?

Most of the Merc V-6's in the late 80's - early 90's carbed engines idle rough and there is not a good fix for other than running Prem-gas, motor doesn't require it but willprobably idle better according to my wrench.
My 89 200 hp has run the same since new.

 

[j_martin]

Re: Checking sync and link settings on 150hp carbed V6?

My 1988 XR4 owner's manual specifically states that the motor will run on regular if it must, but will run better on premium. I run only 92 octane with no alcohol in it.

No stock motor should fight you at idle. There's a difference between the ragged sound of a fairly hot motor wanting to getagoin', and cylinder specific miss at idle that degrades performance and operability. Most wrenchheads can tell the difference.

The more I look into properly tuning mine, the more I think it's a gamble unless pretty sophisticated instrumentation, such as pyrometers and accelerometers are used. I find the crayon applied timing marks on the merc flywheel pretty funny, and scary. Of course you can just set it up rich and slow and be safe.

I do get a wierd rush out of making an old fishing boat and motor walk around the high buck stuff on the lake and maybe even wash them a little with the roostertail.

John

 

[Laddies]

Re: Checking sync and link settings on 150hp carbed V6?

j martin,while I am not an authority on Merc v/6 motors you will find by looking in a Mercury parts manual(online USBoatSupply will work) that all Mercury 150/v6's after serial number OC-239552 to OG-760299 have adjustable low speed needles unless Mercury Marine doesnt know what they built. Hope this helps 8)

 

[j_martin]

Re: Checking sync and link settings on 150hp carbed V6?

Laddies,
I stand corrected. I'm by no means an expert. :%

I looked at the parts diagram but I missed the adjuster. I thought it was the throttle shaft.

From what I've seen and heard, not my personal experience, fuel problems ruin more motors than anything else. One needs to go to the book, and set things where it says. Any further adjustment should be done with a thorough understanding of the consequences.

 

[hkeiner]

Re: Checking sync and link settings on 150hp carbed V6?

Thanks for all the replies. Perhaps my motor is idleing as best as can be expected for a 1996 V6 carbed motor(per Gary's feedback) or perhaps it can be improved a bit by cleaning the carbs and performing the link and sync to standard factory specs. I'll see in the spring when I do this.

I am not planning to tweek the motor outside of factory specs to get improved performance, as it goes pretty darn fast already (on a19' 1996 Maxum XR), almost too fast for a family man with children. Also, I clearly understand that "lean" is "mean" (as in bad) when it comes to carb adjustments on two-stroke outboards.

Best regards

 

[hkeiner]

Re: Checking sync and link settings on 150hp carbed V6?

Guys,

The first step of the link and sync procedures is to check (set) the timing pointer using a TDC dial gauge. I don't have a TDC dial gauge and before I go out an buy one and figure out how to use it, I thought I would check whether this step is important enough in my circumstances to do so.

The motor (1996 Mercury 150hp carbed V6) is ten years old with 270 hrs. on it. I bought it from the original owner who reliably said that he had all motor work done by a mechanic and that he never worked on the motor himself. He also told me that all previous work done on the motor was limited to tune-up and maintenance type stuff. The motor was never disassembled. The motor runs fine at WOT and idles satisfactorily, although I would like to make it idle a little more smoothly if possible. I understand the importance of the timing pointer being correctly set, but am not sure if it is something to reasonably worry about if the history of the motor indicates that the pointer has never been messed with since the motor was new. If I already had a TDC dial indicator I would check the timing pointer for sure, but I hesitate to buy this piece of equipment for a one-time use if it is silly to do so.

My questionns are:

1) Is it reasonable to assume that the timing pointer was properly set by the factory and that I can depend on it to check the timing with a timing light? Is this something that you would do under similar circumstances?

2) Is it better to just go ahead and buy a TDC dial gauge and check the timing indicator for correctness, just to learn how to use it if nothing else? Is a TDC dial guage a piece of equipment that all owners of outboards (that do their own work whenever practical) should have in their toolbox anyways?

This newbie boat owner appreciates the opinions of you seasoned and experienced boat owners.

 

[ragu]

Re: Checking sync and link settings on 150hp carbed V6?

I think by TDC you mean top dead center of the piston. all you need is a dial indicator and a magnetic base not very expensive if you have a harbor freight store close by you can get the whole setup for around 20 bucks stick the end of the indicator in the spark plug hole and turn engine over by hand you will see the indicator rise and fall when it is at the peak you are at top dead center TDC

 

[hkeiner]

Re: Checking sync and link settings on 150hp carbed V6?

Well, I guess I should understand what I am doing if I am going to buy a dial gauge and perform this link and sync step properly. However, I am still a little unclear on this particular step.

The Mercury shop manual contains the below instructions (I have summarized them) for setting the timing pointer:

1) Remove all spark plugs and ground wires
2) Install dial gauge into spark plug #1 hole
3) Turn motor by hand until dial gauge shows piston #1 to be at TDC (top dead center)
4) Set dial gauge to zero
5) Turn motor by hand until dial gauge shows .462''
6) Set timing pointer to align with the .462'' marking on flywheel
7) Remove dial gauge and perform timing.


a) What is the correct type of dial gauge to buy? I presume that it should screw into the spark plug thread, have a range of at least .50 inches, and have decimal gradients in the thousandths of an inch (to locate the .462" position on the dial). I presume that a gauge (or other tool) that only helps you find TDC would not be sufficient.

b) Why is the a .462" marking on the flywheel significant? I understand that the piston is also in the .462" position (using the dial gauge to position the piston at .462 from TDC) but would you not get the same result by leaving the piston at TDC and aligning the timing pointer to a TDC marking on the flywheel? Couldn't any other arbitrary positon on the flywheel be used, as long as the measure on the flywheel and the dial gauge are the same?

My lack of understanding the above is why my first inclination was to assume the timeing pointer is correctly positioned already and skip this step in the link & sync procedures. After getting your responses above, I am now inclined to do this step but I want to understand what I am doing.

Thanks for any additional information on this.

 

[ragu]

Re: Checking sync and link settings on 150hp carbed V6?

get a 1 inch dial indicator and a cheap magnetic base one revolution on the indicator is .100 thousandths but in my seloc book i dont see anything referring to .462 just says to get piston on number one at TDC wich is easy to do just watch the indicator till it reaches its highest point I think laddies has a good thing on here with link and sync do a search for it it seems better than the one in the seloc book easier to understand for sure

 

[ragu]

Re: Checking sync and link settings on 150hp carbed V6?

Goto the top of this page click on boating forums then enter forums scroll down and you will see sync an lync by clams cannino he makes it very easy check it out

 

[hkeiner]

Re: Checking sync and link settings on 150hp carbed V6?

Thanks for the reply. Yes, I have read the other threads on link and sync. I understand the description for setting the timing pointer to the TDC marking on the flywheel (after using the dial gauge or other tool to position the cylinder to TDC) which is the typical way to do it.

However, none of the posts describe setting the timing pointer to the .462" position on the flywheel (after using the dial gauge to position the piston to the .462" position in the bore) , which is peculiar to me and that is the primary reason for my questions.

Any thoughts as to why .462" is specified in the Mercury shop manual?