1982 90HP Link and Sync

[thelm]

Hi All,

New to the board and have a few questions. I've learned a lot reading on this site and appreciate it very much.

1982 Merc 90HP SN6188394 ? My SELOC manual says primary pickup timing is 4 ? 6 BTDC. Link and Sync procedure in FAQ says 3-4 BTDC which is fine. Problem is there is an OEM decal on the forward plate of my engine that says primary pickup timing should be set at 4 ? 5 ATDC. I?ve found numerous mistakes in the SELOC manual so I?m not really bothered by that. I am however concerned that I don?t understand the FAQ Link and Sync procedure which states ?As the throttle is advanced, the spark timing advances toward TDC and then to before TDC. As the timing is just passing TDC the 1st (minor) throttle pickup should hit and start opening the carbs.? On my engine, the carbs are directly connected to the throttle arm by a linkage. As soon as the throttle arm is moved off of the idle stop, the carbs begin to open. As throttle is increased there is no period during which the timing is being advanced with the carbs closed. This is different than on the earlier 90HP engines.

Any comments on how the FAQ Link and Sync procedure relates to the 1980 ?1986 90HP engines would be appreciated.

The SELOC manual gives the procedure for synchronizing which I can follow. There are both primary pickup and maximum advance adjustment screws on the engine. Where should I set the primary pickup timing? 4 ? 6 BTDC or 4 - 5 ATDC?

Thanks for any help you can give me.

 

[AMD Rules]

Re: 1982 90HP Link and Sync

Disregard what the label says on the motor, and follow this procedure. You won't be disappointed.

Timing and Sync of Merc Inlines (to 1988)


.

 

[thelm]

Re: 1982 90HP Link and Sync

Thanks AMD for the quick reply.

I've read the procedure you linked me too several times over the past few days and setting the primary pickup timing on my engine is still not clear to me. The procedure calls for setting the primary pickup timing at 3 - 4 BTDC as the carbs just begin to open. On the 82 Merc 90, this appears to happen while the throttle arm is still on the idle stop. As soon as the arm moves, the carbs start to open. The manual calls for adjusting the primary pickup timing on this engine while the throttle arm is on the idle stop. I guess that is what I need to do, but not what the Link and Sync procedure says.

 

[AMD Rules]

Re: 1982 90HP Link and Sync

Its not typical for it to be sitting on the idle stop, and have the primary pickup already in contact. Did you double check your accurate TDC position, and the belt alignment to the smaller pulley?

 

[thelm]

Re: 1982 90HP Link and Sync

This is a later model 90 without a distributor, thus no timing belt. Your '86 115 should be very similar. The link and sync procedure makes perfect sense to me when considering the pre 1980 L6's. I'm wondering if the concept of a primary pickup really applies to the later models. As I said in my first post, the throttle arm is connected to the cam by a direct linkage and the carbs start to open as soon as the arm moves off the idle stop. This is different than the pre 1980 models.

 

[AMD Rules]

Re: 1982 90HP Link and Sync

Sorry... I had a momentary lapse of reason there. Overlooked where you posted the year.

The primary pickup does apply to the ADI models. I'll pop the top on mine later today if I get a sec and review what the relationship between idle position and primary pickup is.

 

[thelm]

Re: 1982 90HP Link and Sync

Thanks AMD,

According to my manual, primary timing is adjusted while the throttle arm is against the idle stop. This too is different than older models.

I appreciate your taking the time to help me understand this.

 

[thelm]

Re: 1982 90HP Link and Sync

Just wanted to report back on my results. Hopefully this will help someone else trying to tune this motor.

I verified the .464 mark on the flywheel using a dial indicator. It was spot on. I then adjusted the primary pickup screw to achieve 5? ATDC while cranking with the throttle arm on the idle stop. The SELOC manual had this wrong at 4 ? 6? BTDC. Next I adjusted the spark advance screw to achieve 20? BTDC while cranking with the throttle arm on the high speed stop. Adjusted the carb roller arm so shutters were fully closed / open at idle / full throttle. Opened all three idle mix screws 1-1/2 turns out from lightly seated. Started up in the water and adjusted idle speed and mix to achieve lowest stable idle in forward gear. Idle mix screws ended up ? turn out from point of stumble. I got a low smooth idle and great hole shot. Runs like a Swiss watch.

The Link and Sync procedure posted in FAQ does not seem to meet the need for timing this engine after about 1980.

 

[Chris1956]

Re: 1982 90HP Link and Sync

thelm, I am not sure I agree with your criticism of the Link and Synch post. It clearly states that your idle timing may vary, and gives a suggestion about what spec to use if you do not know the actual spec.

Since the link and synch posting covers quite a few models, it is necessarily more general in nature, and requires the user to analyse the intent of the procedure and react accordingly. I would recommend you purchase an OEM service manual for your exact motor.

 

[thelm]

Re: 1982 90HP Link and Sync

Chris,

I didn't mean to be critical but the procedure is somewhat confusing to someone setting primary pickup timing on an L6 newer than 1980. Link and Sync talks about idle timing being ATDC and advancing through TDC as the first pickup hits and the carbs just begin to open. On the post 1980 L6's, the carbs start to open as soon as the throttle arm moves off the idle stop. At that time, spark timing is still 5? ATDC and does not hit the recommended 3 - 4? BTDC until the carbs are further open. If you set my engine up so timing is 3 - 4? BTDC just as the carbs begin to open it won't run right because the idle timing will be too advanced.

The rest of the Link and Sync procedure was very helpful and I actually followed it fairly closely.

Tom

 

[Chris1956]

Re: 1982 90HP Link and Sync

Tom, I f I understood you correctly, there may be an adustment on your motor that was overlooked. I am not an expert on your application, however, the inlines I have seen allowed the throttle stop to retard the idle timing well below the spec. For example, if idle pickup timing was 4* ATDC, the throttle stop might have timing of 8* ATDC. You might look to see if there is a way to change the link length between the throttle arm and the trigger. If I think about it this PM, I will look in my OEM book and see if I can find it.

 

[AMD Rules]

Re: 1982 90HP Link and Sync

Idle timing (primary timing event one) adjustment will not affect the overall picture. The rough guideline in the FAQ does apply to all , through to 1988 and has been verified to function just fine. I can quote the author in this regard if required. I have the OEM manuals for the inlines and am aware that the factory spec for years and horsepowers varies from ATDC to BTDC. Point being is that specific setting will not affect overall motor performance.

Glad you got it sorted out.

 

[thelm]

Re: 1982 90HP Link and Sync

Thanks Chris,

I'll be interested to know what you come up with. From what I can see, there is no way to set this up so timing advances before the carbs start to open. The throttle arm is hard linked to the carb cam so anytime it moves, the carb shutters move. There is a secondary link to the trigger through a spring loaded mechanism. If you leave a gap between the carb roller and the cam so the cam can move before the carbs begin to open, the shutters would not be completely open at WOT because there would not be enough range of motion. Not sure if this is making sense to anyone. The engine now runs great so I think I have it set up right.

Tom

 

[Chris1956]

Re: 1982 90HP Link and Sync

Tom, My OEM Manual only covered models to 1978 or so. It did have some ADI ignition procedures for inline 4s. On these older models the trigger is hard linked ( link is non adjustable)to the throttle arm. After the arm advances to idle timing spec, it contacts the carbs. In this way, if you back off the idle stop screw, the timing will retard further after the carbs close.

I will guess the spring on the trigger link caused th trigger lnk to shorten and allow the carbs to open fully, after the trigger has reached max spark advance. This is a different setup. I wonder what my '93 V6 has? Maybe I can look that up. I havent had to work on it yet, so I am ignorant.

Not too much help, sorry.

 

[AMD Rules]

Re: 1982 90HP Link and Sync

Thanks Chris,

I'll be interested to know what you come up with. From what I can see, there is no way to set this up so timing advances before the carbs start to open. The throttle arm is hard linked to the carb cam so anytime it moves, the carb shutters move. There is a secondary link to the trigger through a spring loaded mechanism. If you leave a gap between the carb roller and the cam so the cam can move before the carbs begin to open, the shutters would not be completely open at WOT because there would not be enough range of motion. Not sure if this is making sense to anyone. The engine now runs great so I think I have it set up right.

Tom

I totally agree that if its running well.. there's no need to change anything. But the purposes of discussion, I hope you don't mind if we look at a few things in more detail.

I just went out to inspect my motor based on one of your comments;

If you leave a gap between the carb roller and the cam so the cam can move before the carbs begin to open, the shutters would not be completely open at WOT because there would not be enough range of motion.

I'll admit I set mine up per the manual, and that its description differs from the FAQ somewhat.

Step ONE is to set the approximate idle stop screw initially so that the lines on the crankcase bracket are aligned per image (c) shown below.

Step TWO is to loosen the carb lever screw (b) shown below, and hold the idle stop screw (a) shown above against its stop. Position carb shutter fully closed and adjust roller so that it just touches the throttle cam (c) shown below.

Step THREE is to disconect the idle stabilizer (or throw it out..lol) and then hook up timing light to #1 wire (all other plugs removed), hold throttle lever idle screw against its stop and crank engine. Adjust primary pickup screw (a) shown below to appropriate timing pointer mark. (What number to aim for here is what we were discussing earlier.)

From there you go on to set the maximum advance, then the wot carb shutter opening, and finally go back to re-check idle rpms as per the FAQ.

With my throttle in neutral, the throttle cam and roller are very close, but I don't think they are touching.

Factory specs for primary pickup on the ADI models are as follows:

90hp 1-3? BTDC
115hp 5-7? ATDC
140hp 4-6? ATDC

I'm interested to hear your thoughts, based on what is shown above.

Hope it helps.

 

[thelm]

Re: 1982 90HP Link and Sync

Thanks AMD, those pictures look very familiar to me.

I followed the described procedure pretty closely last weekend when I got my motor running well. The only real discrepancy is the primary timing. SELOC says 4 ? 6? BTDC, your OEM manual says 1 ? 3? BTDC FAQ says 3 ? 4? BTDC, my engine decal says 4 ? 5? ATDC. I set up at 5? ATDC. It looked like primary timing was set at 5? BTDC before my tune up. The engine idles much better now than it did but I can?t say for sure it?s because of primary timing.

The OEM and SELOC procedures call for setting up the carb lever roller so it just touches the throttle cam when at the idle stop. In this case, the carb shutters start to open as soon as the throttle arm is moved off the idle stop (timing is advancing as well). This has been my main point of confusion with the FAQ procedure. Maybe someone with your level of experience can read between the lines, understand what is intended and extrapolate to an engine that is set up slightly differently. For a neophyte like me it caused confusion.

For purpose of clarity, I noticed that in the second picture, arrow c is pointing to the carb lever roller, not the throttle cam as labeled. Even the OEM manual has mistakes.

I also wonder why you wouldn?t wait until after step 3 to adjust the carb lever screw. The position of the throttle arm and thus throttle cam will change in step 3 so why not wait until that is done before setting the roller? I?m probably getting a bit picky now.

Based on my recent experience, I distilled out a written procedure for my engine so I will have it the next time.

Timing and Synchronization 1982 Mercury 90HP L6
1.Disconnect Throttle cable.
2.Loosen carb lever adjustment screw.
3.Remove plugs 2 ? 6 and inspect.
4.Re-attach wires to plugs, tape plugs together and ground to the block as a group.
5.While holding throttle arm at idle stop, crank engine and adjust idle speed screw to align marks on throttle cam and powerhead bracket.
6.Attach timing light to #1 plug.
7. While holding throttle arm at idle stop, crank engine and adjust pickup screw to set timing at 4 ? 5? ATDC using timing light.
8.With carb shutters fully closed and throttle arm held at idle stop, re-tighten carb lever adjustment screw so roller is barely touching cam.
9.While holding throttle arm at full throttle stop, adjust full throttle stop screw so carbs are full open and just hitting their stops.
10.While holding throttle arm at full throttle stop, crank engine and adjust spark advance screw to set timing at 20? BTDC.
11.Install plugs, proceed to setting idle mix and speed

Setting Idle Mix / Speed 1982 Mercury 90HP L6

1.Set all three idle mixture adjustment screws to 1-1/2 turns out from lightly seated.
2.Start engine in water and allow to warm up.
3.With boat in the water and in forward gear, adjust idle speed screw to maintain lowest stable idle.
4.Adjust idle mixture screws one at a time starting at the bottom by turning in until engine stumbles, then quickly open ? turn. Repeat process until satisfied.
5.Re-adjust idle speed screw to maintain lowest stable idle while in forward gear.
6.With shifter in neutral, adjust and connect throttle cable so there is light to moderate pressure holding the throttle arm against the idle stop.
7.Test hole shot. If hesitation occurs, open each idle mixture screw ? turn and re-test. Repeat as necessary.
8.Re-adjust idle speed screw if necessary to maintain lowest stable idle. Re-adjust throttle cable if idle speed screw is adjusted.

Thanks for the comments and feedback and thanks AMD for posting pictures and procedure.

 

[Ware5150]

Re: 1985 115HP Link and Sync

Re: 1985 115HP Link and Sync

AMD,

You seem to have great knowledge that I could use. I have followed all link and sync setups and cant get my boat to run right. Number one, after the initial setups it will not idle at this point. I can adjust the throttle lever up and maintain idle but it stalls when I put it in gear. Next I have adjusted the timing to maintain idle ran great in the yard. Get to the lake and would not run.

So far I have rebuilt the carbs, fuel pump, new hoses and plugs. I use a large trash can to get it to run at home. I will rev great but dies under load when I get to the lake.

7/2/09 I followed the link and sync above. Boat will crank and Idle as long as the throttle arm is advanced about 3/4 to 1/2 inch from the stop. The stop is set to ahline the arrows on the cranking head. I have tried the idle screws at 1 to 1 1/2 and more. I can slowly lower the throttle down to about 1100 rpms any more and it dies.

Anyone please tell me what I have done wrong or what I am missing.

Ware5150

 

[AMD Rules]

Re: 1982 90HP Link and Sync

Ware5150,

Start your own thread, and I'll respond with some ideas.

 

[xanderman]

Re: 1982 90HP Link and Sync

I followed the described procedure pretty closely last weekend when I got my motor running well. The only real discrepancy is the primary timing. SELOC says 4 ? 6? BTDC, your OEM manual says 1 ? 3? BTDC FAQ says 3 ? 4? BTDC, my engine decal says 4 ? 5? ATDC. I set up at 5? ATDC. It looked like primary timing was set at 5? BTDC before my tune up. The engine idles much better now than it did but I can?t say for sure it?s because of primary timing.



Thanks everybody for your time and effort into providing great information for all the rookies like myself.

I came here yesterday because I was setting the timing as described by the manual for my 1982 90hp 6cyl inline when I came to an impasse while setting the primary timing. I found TDC with a dial guage, adjusted the timing marker on the housing to align with the sticker on the flywheel, then about to use the timing light to adjust to "the mark" when I realized... there is no mark!

The manual does not say if it is to .464 BTDC, 0*, it wasn't until reading this thread that i realized there is a sticker on the engine which says 4-5* ATDC.

Set it there and 20* advanced at WOT and it seems to run fine, I'll test it out today and hopefully have improved performance.

It was originally running "fine" set at 0* primary and 8* BTDC at full advance, but the engine performed basically like a 50hp output, max 29mph with a 17' glass boat and light load. When slowing from WOT I could actually hear the reed valves flapping in the wind and popping because the timing was so far retarded, I'm sure glad I spent the $50 for a timing light yesterday!

I used to run a 90 on a 15' and could get 55mph with a heavy load, scared stupid with a light load (chine walking), so i know this engine was not running up to par... just running.

I have to agree that the link and sync guide is useful to 'roughly' set up all motors in the range described, it is very valuable for anyone just trying to get their motor running without purchasing a manual and posting specs for all the different engines would be tiresome, but it could not possibly tune all of these different motors to their maximum potential using the same settings for all of them.

My personal opinion, untested, is that the manual with specifications specific to the engine should supercede a shotgun spec for all motors.