Inline 6 150hp Link&sync advice!

[sourbsted]

I have a 73 mercury blueband 150hp ser: 8008578. I have the mercury workshop manual, which I have been following. The carbs have been rebuilt, fuel pumps rebuilt, new timing belt, cleaned all the electrical connections. All cylinders have compression between 140-150psi.

The boat struggles to plain out, hesitates through low rpm then, if i'm lucky it will plane out and go hard like a young dog off a lead. I have been told by everyone I NEED to do the link&sync.

I'm stuck on this link&sync procedure.

- Reverse boat on trailer into water, start it warm it up
- Starts good on fast idle, doesnt idle 100% cause I would need to adjust the idle mixtures. At this stage they are set at 1 1/4 turns out.

- Here's my problem: I obviously want to adjust the "primary throttle pickup" to get the hole shot test better. I CANNOT get to BTDC 4-6 degree's like I am suppose to. At very low idle it stays at ATDC 10 degree's. If I try to lower the idle any more it just goes straight to BTDC 464 degrees then stalls. Am I missing something here or what?

- At TDC I have the alignment pointer aimed at Zero on the flywheel. Just like I do any other engine I have ever worked on. It's hard to figure out what to do in the workshop manual cause, they go on about serial numbers.
I have changed the timing pointer so it aligns with the zero on the flywheel. It may have aligned on the BTDC 4 degree's before I changed it.
Am I suppose to change the pointer so rather than pointing at ATDC 10 degrees on idle, change the pointer so it's on BTDC 4 degree's.??

Obviously if I didnt have to work for a living I would figure it out. And I tryed to find someone to work on it but they refuse to work on it because of it's age, told me to wait to the off season when their work dies down a bit.

 

[Laddies]

Re: Inline 6 150hp Link&sync advice!

The first thing to do is use a dial indicator done #1 and turn the engine to .464 then set the point to the .464 mark on the flywheel

 

[Chris1956]

Re: Inline 6 150hp Link&sync advice!

Those old Mercs had timing marks on the cowling support. Set the flywheel to TDC, using the decal and the timing mark. Now set the distributor pully cast arrow to point to the three (or one) dots (actually a punch) on the flywheel. Now the distributor is properly timed. Continue the link and synch. Idle timing pickup is 4-6* BTDC. Max spark advance is 21* BTDC.

 

[oldman570]

Re: Inline 6 150hp Link&sync advice!

Here is an old post that might help you out.
Timing and Sync of Merc Inlines (to 1988)



Thanks to clamscanino for this info.
__________________________________________
Manual specs are different for each but this is close enough to get them all REAL close. This assumes nothing is broken or "wrong" with it. This also assumes that the timing pointer is properly adjusted (if adjustable) to accurately read TDC of the #1 piston.

This basic procedure will work for all the 2/3/4/6 cylinder inlines from 1960 to 1988. It's not for the newer 3 and 4 cylinder loopers.

Engine off

Disconnect throttle cable

Pull throttle arm to full throttle and verify carbs open fully. Adjust main throttle stop so that the carbs are JUST hitting thier own little throttle stops. The idea here is that you want the screw stop and NOT the carbs acting as the "final stop" for your throttle lever.

Return the throttle to idle, carbs should be closed. Set all idle screws to 1 3/4 turns out from lightly seated.

Remove all plugs except #1, hook a timing light to #1. Then follow the narritive.

When the throttle is in the idle position the carbs should be fully closed and the ignition retarded. It is the amount of retardation that determines your idle speed and is set later with the idle stop screw.

Timing Event One - throttle pickup.
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 to open the carbs. Use the timing light. Adjust the tang or trigger screw to make this a reality. All of them are speced different, but if the 1st pickup hits at 3-4 degrees BTDC advance - you win. Use the timing light with a friend cranking it to complete this setting.

Timing Event Two - max advance.
As you continue to advance the throttle the timing will advance while the carbs slowly open a bit more. The next adjustment is max advance, this is the point where the distibutor (or trigger) can advance no more. Set the max-advance stop to 21 degrees for "direct charge" crossflow inlines and 34 degrees for the older plain vanilla crossflows. Use the light, - err to the side of caution.

Right after max advance, further throttle motion should cause the second throttle pickup to hit and open the carbs to full. You already set that -now verify it.

Leave the throttle cable disconnected and go to the water. Leave the boat strapped to the trailer and back it in so it's deep enought to run. Have a friend crank it while you operate the choke and throttle. Warm it up at 1500 rpms's.

When "warm" adjust the idle stop screw for about 800 rpm and then ajust your idle needle(s) in (one at a time) till the motor stumbles. Quickly backing it out 1/2 turn from "stumble" will usually save it from needing a re-start. Do that for all the idle screws. Re-set idle stop for 800.

Now have your friend put it in gear (make SURE you are on the transom NOT in the water) and reset your idle stop for as low as you can get it. 500-600rpm is great if your old reeds will let it idle that low in gear. Now, re-adjust the idle screws, in to stumble, then 1/2 turn out. When you've gone back and forth with that a few times and have it "perfect" - adjust each one out 1/4 turn.

Reset the idle stop so that it's about 700-800 out of gear and 500-600 in gear. Sometimes bad reeds won't let you get that low, you've GOT to get it under 1000 in neutral (worst case) to avoid beating up your lower unit when you shift into gear, even 1000 is "bad" but like I said "worst case".

Now adjust (and hook up)the throttle cable so that with the shifter in neutral, there is light to moderate pressure holding the throttle arm against the idle stop.

Take the boat off the trailer and go out in the water. Try the hole shot. If it falls on it's face try adjusting the idle screws out 1/4 turn at a time (all of them together) till you can get a hole shot. You can kind of do this on the trailer at the ramp, but it's not really safe for you, the boat, or the tow vehicle.

You're done.

-W

Oldman570

 

[sourbsted]

Re: Inline 6 150hp Link&sync advice!

I tryed doing clams procedure but I got the same result. Just can't get anything below TDC. I only BTDC 464 and on a very low idle. Then if I raise the rpm it shoots straight to ATDC 10 degrees. It's goes well once I can get past the surging.

 

[oldman570]

Re: Inline 6 150hp Link&sync advice!

QUOTE=sourbsted;4093033]I tryed doing clams procedure but I got the same result. Just can't get anything below TDC. I only BTDC 464 and on a very low idle. Then if I raise the rpm it shoots straight to ATDC 10 degrees. It's goes well once I can get past the surging.[/QUOTE]

I do think something is very wrong with your workings . I have never seen a motor with a timming work backwards. All the ones I have worked on always has the timming at idle going from 2 or 4 degrees ATDC to BTDC when the throtal is advanced to open the carbs and advance the timming. You might want to check the timming again and see if the distrubiter is not sitcking from the bearring not having been greesed as needed. You might want to be sure that the pointer, is set at TDC as Chris has stated. You might want to check the timming of the distrubetor and flywheel belt as it might need to be adjusted one tooth more as the motor will not run and time correctly if it is set late as the manual states JMO
Oldman570

 

[Lone Duck]

Re: Inline 6 150hp Link&sync advice!

What oldsman said. I suspect your belt is out 1 tooth.

 

[sourbsted]

Re: Inline 6 150hp Link&sync advice!

I'll get some dial indicators from work, and do TDC check again. I'll take photos shows how it looks. This all started when I snapped a timing belt. The bearings in the dizzy seem good.

This is how it went before I worked out it was a tooth out. https://www.youtube.com/watch?v=Av0kSlkI0nY&feature=youtube_gdata_player
This is how it went after I fixed the tooth out problem. It's go's well once it gets going. https://www.youtube.com/watch?v=-x-ek8aH0SU&feature=youtube_gdata_player

Have any of you's seen a I6 get onto a plane even if its a tooth out?
I cant get my head what laddies said about 464 settings, its in the merc manual too.

 

[sourbsted]

Re: Inline 6 150hp Link&sync advice!

One other thing I should point out that's a little odd about the motor. When you reassemble the dizzy you have to make shore that the two arrows that someone has engraved into cap and dizzy body line up. Iv'e always been aware of it and made shore the arrows line up. It has a couple of mm play in it before you tighten up the retaining ring.
I'll take pics of it..

 

[Maxz695]

Re: Inline 6 150hp Link&sync advice!

first start you mixture screws at 1 1/2 then adjust out for best holeshot afterwards. You have it set too lean, It can take up to 2 to 2 1/4 turns before finding the sweet spot. Once the low idle screw is locked with the cam just touching the carb lever it should not be re adjusted use the low idle timing screw to make the adjustment for best idol. Re adjust the mixture screws again for best holeshot and you are properly adjusted at that point. Check the hi idol timing at WOT on the water to be sure it is correct.
set the low idle timing to spec with the spark plugs removed and just at cranking speed. Not running JMO

 

[Chris1956]

Re: Inline 6 150hp Link&sync advice!

Not to be insulting, but are you reading the timing decal properly? As throttle is advanced, timing should go more advanced (larger number BTDC). You describe the opposite, which is real wierd. Motor is running in correct direction. right?

 

[sourbsted]

Re: Inline 6 150hp Link&sync advice!

Haha.. no offence taken. What rpm would you expect to see it go at BTDC 4 degrees? The primary pickup plate is allmost out of adjustment, which make me think its way out.. I need tacho, got one coming..

 

[sourbsted]

Re: Inline 6 150hp Link&sync advice!

Ok this photo, can you see the two white paint dots. One is on 22 degree ATDC. The other is on 6 degrees ATDC. Correct?? Thats where it sits on TDC.

 

[Lone Duck]

Re: Inline 6 150hp Link&sync advice!

Ok this photo, can you see the two white paint dots. One is on 22 degree ATDC. The other is on 6 degrees ATDC. Correct?? Thats where it sits on TDC.

No. your fly wheel spins clockwise your white dots are BTDC. To the right of your TDC mark at the end of the timing decal, you will see 3 punch dots in a line one below the other. Make absolutely sure that the arrow on your distributor pulley is in perfect alignment with the dots when you instal the belt. This is done when your pointer and TDC mark have been aligned.

 

[oldman570]

Re: Inline 6 150hp Link&sync advice!

With the plugs out and #1 plug grounded to the block and the timming light hooked to the #1 plug wire the starter should spin the motor over colse to 400 to 600 RPM. This is stated in the lync an sync info I posted earlier. As Lone Duck states, in your picture of the timming pointer, to the right twards the 3 dots is ATDC and to the left where the paint dots are is BTDC. The dots are where the timming needs to be inorder to set the carbs correctly at 4 BTDC and the one at 22 BTDC is for the WOT timming setting of the distrubtor advance stop. Don't get flustered over the setup. I have found that I have had to go back and reread several things slowly while looking at the motor to get a good understanding of just what has to happen and when, before I have gotten it right. After you have done it a couple of times, it gets alot easier. Book learnin is good, but hands on is the best teacher. JMO
Oldman570

 

[sourbsted]

Re: Inline 6 150hp Link&sync advice!

Thank mate, I got camera happy. Here's where it stays on a slow idle ATDC 10 degrees.

Here's the arrows on the dizzy I was talking about. There's a bit of slop in dizzy cap, that's why I think they put arrows on the cap.

I'm pretty shore the arrow on top of dizzy pulley points at the three dots on the flywheel. I will pull it down and get camera happy..
Everyones help and advice is appreciated!

 

[sourbsted]

Re: Inline 6 150hp Link&sync advice!

The arrow looks perfect! I have no idea why it doesn't go BTDC to on slow idle..

 

[mercurymang]

Re: Inline 6 150hp Link&sync advice!

I'm thinking that looks off. Shouldn't that arrow be pointing to the center of the crank?

 

[Lone Duck]

Re: Inline 6 150hp Link&sync advice!

I'm thinking that looks off. Shouldn't that arrow be pointing to the center of the crank?

Looks off to me also. I think he has to go back and realign. Here it is from the book. (1)remove all spk plugs from engine. (2) Turn fly wheel until 3 dots on fly wheel timing decal is aligned with centre of distributer shaft. (3) turn distributor pulley until arrow is aligned with 3 dots on timing decal, Then slip timing belt over pulley. After this and only after this do you set your TDC with dial indicator.

 

[oldman570]

Re: Inline 6 150hp Link&sync advice!

Yes the pointer on the distubertor , dots on the flywheel, and center of the crankshaft have always lined up when I have done a link and sync on them. If you line up every thing as it should be then the timming marks will show the TDC mark and pointer more adavanced that what is shown. The belt timming being off one tooth will also make a diffrence of where things should sync up . JMO
Oldman570