V-6 200hp Blackmax Timing set-up

[philbur]

OK...the plot thickens....

I managed to screw around with a few erratic timing settings and the motor now idles fairly reliably...
I has lots of "snap" when I crank the carb linkage and the excess oil in the exhaust has settled down to a reasonable amount. I am not going to rev this thing too long in neutral as I know what that does to the poor con-rods and bearings.

The problem is the timing, though...I have set the initial ATDC at 10 degrees...with closed throttle (although the book says 6 or 7 degrees ATDC), cranking speed, all plugs out except #1 (obviously), engine harness disconnected, Idle Stabilizer wires disconnected (white and black, red still connected). and when I try to get my 22 BTDC on full throttle/advance @ cranking rpm I am only able to bring the motor to about 4 degrees ATDC!

Am I missing something?...and does the 22 BTDC make any sense? Seems to be the way to replicate what the ADVANCE should be when your revs are up around 5500...I think...but have I not taken something into account?
The manual has the procedure fairly well documented but there is NO WAY I can get this unit to crank at ANY numbers approaching 22 BTDC. regardless of how far I have rotated the Trigger....and besides...the further you go on the adjustment screws...the more ATDC you get...not the other way around.

The Idle Advance screw moves the trigger "counter-clockwise" and the Full Throttle Advance lever ALSO moves the trigger in the same direction as you apply more throttle.... I am confusing myself, I think,,,but it almost seems as if the manual SHOULD indicate that you need to do the WOT Advance setting while your motor is under load, at top indicated revs....The manual indicates that the proper timing settings @cranking speeds is 7degrees ATDC (Idle, throttle fully closed) and 22 BTDC (WOT, full advance, throttle fully open).

I apologize for not making much sense...but this old mechanic has timed his fair share of automotive engines...and the concepts and intrinsics of timing, in general, are well known to me...or so I thought....along comes this 2.4 marine outboard...and I quickly learn that even though the pistons reciprocate under pressure from expanding gases due to combustion...and the heavy wiggly thingy goes round and round...all is not exactly the same between them....

I would also like to know if there is a spec for the initial measurement for the Trigger linkage?, as I have replaced mine, and the rod and ball-socket assy have been re-assembled.

Any comments are welcome and appreciated....

BTW. When I bring the ilde timing into spec it idles poorly...and needs to be advanced to around 14 or 16 ATDC for it to stay running.

 

[hkeiner]

Re: V-6 200hp Blackmax Timing set-up

I don't have a clear enough understanding of your narrative to recognize what your specific problem is but if I were in your situation I would perform a full link and sync on the motor. Every step in the link and sync has to be done correctly and in the correct order. Each step/setting is dependent on all previous steps/settings being correct. If you just screw around (your words) with one setting when a previous link and sync step/setting is at fault, you can get things pretty messed up and unsolvable without doing a proper link and sync first. Just my thoughts...

 

[philbur]

Re: V-6 200hp Blackmax Timing set-up

Hi HK...
Yes...I agree...and I have done the L&S twice now to be sure I am not just guessing.

This post is partly from an earlier one, so please excuse the rambling.
In short, I am only worried about the 22 BTDC requirement, as I do not have enough adjustment room on the advance lever to get anywhere near the required spec.
The "screwing around" was done after the initial L&S to better smooth out the idle, and reduce the amount of oil/fuel being bled from the exhaust.

Should I even worry about getting the 22BTDC?....or rather just ensure my initial Idle Advance is good and then load it up on the water and see how the motor responds to gradual increases in throttle? Once again, I am rather confident that the timing is close enough to spec at cranking speed and closed throttle, I am just confused as to how, exactly you can get 22BTDC on a timing gun while cranking and false-forwarding the advance lever.
Does that help?

 

[hkeiner]

Re: V-6 200hp Blackmax Timing set-up

I am only worried about the 22 BTDC requirement, as I do not have enough adjustment room on the advance lever to get anywhere near the required spec.

The maximum timing adjustment is a link and sync step and it is very important that it be set to specs. If you can not set it to specs, I would only conclude that (1) a previous link and sync step was incorrectly done , (2) you are misreading the maximum timing spec in the manual, or (3) your have the timing light on the wrong spark plug wire. The maximum timing is set while cranking the motor with spark plugs removed and you should be able to set it to spec. Shop manuals usually include a note such as "All timing adjustments made to outboard under cranking speed conditions should be verified with outboard running and adjustments made if necessary. This is due to advance characteristics of individual ignition systems.". Frankly, I never check the timing at WOT running out on the water. I accept the maximum timing adjustment I set when cranking the motor with spark plugs removed.

For idle speed timing, the adjustment spec is a range and it applies only to when the motor is idling. There is not much (any) danger to damaging the motor if the idle adjustment is a bit off. It just won't idle as well.

I may be telling you things your already know, but this is the best I have to offer. Good luck...

 

[philbur]

Re: V-6 200hp Blackmax Timing set-up

I appreciate your help and opinions, HK...

I am going to re-visit the trigger problem I had...and double check that I was sent the correct part for my motor...if the spec is supposed to be 22BTDC@cranking, with full advance, then I have no other explanation for why I can only get about 4ATDC.

Thanks for your time!

 

[hkeiner]

Re: V-6 200hp Blackmax Timing set-up

Have you confirmed that the timing pointer is aligned to the correct mark on the flywheel, using a dial indicator on cylinder #1? This is one of the first link and sync steps.

 

[cannonford57]

Re: V-6 200hp Blackmax Timing set-up

i know you have already,but someones gonna ask if you have verified tdc on the flywheel and the cover at the timing hash marks using #1 piston of course

 

[philbur]

Re: V-6 200hp Blackmax Timing set-up

Hi Guys....Thanks for your thoughts...
As I had just finished a complete rebuild on this motor... I have, indeed verified the TDC - 0.462 setting and adjusted the timing pointer...but thanks for asking...heh heh...

It is really weird, but I did the complete L&S again today...only to arrive at the same problems....

One thing to note, perhaps...is that when I do the idle timing (7-ATDC) the trigger is positioned just shy of halfway through it's complete travel. In other words, I need to back out the idle advance adjustment screw so far that it actually ends up rubbing against a peice of the block (I can get a photo of it if you wish to see what I mean). This makes me believe that there is something whacky going on as there could never have been a timing adjustment this extreme in the past....and I assure you that I actually know engine repair quite well and have been in the trade for 30 years...just not a lot of experience with diagnosing big Mercs...
I am going to run it up again tomorrow and see what exactly is going on while idling in my hommade test tank...if it wasn't for the damn timing specs being off I probably would have put it in the water to break it in...as the idle is acceptable, and it "seems" to snap pretty good when I crank the carb linkage....but once again..this occurs when I set the advance myself using the running condition, cylinder temps, and plug condition as the indicators..not the static timing @ cranking method.

I will get up extra early and even go over the switch boxes, coils, and trigger specs again...just to be sure...but this might all have been a non-issue if I managed to find SOMEONE who could have supplied me with a correct Flywheel hub and trigger in the first place....

 

[CharlieB]

Re: V-6 200hp Blackmax Timing set-up

Something is indexed incorrectly, like the timing trigger magnets under the flywheel.

You are going to need to look at this to see if they have somehow shifted position, or possibly you have the incorrect flywheel for this ignition/model.

You should have almost a 30 degree range of motion on the timer plate from an idle to WOT.

If I understand you correctly, you are saying that at an idle your timer plate is already at or near the middle of its range of motion.

Either the flywheel key has sheared and allowed the flywheel to shift @ 15 degrees OR the timer magnets under/on the inner flywheel hub have shifted.

 

[philbur]

Re: V-6 200hp Blackmax Timing set-up

Ok...that makes sense...and I am suspecting the same thing...
But the Flywheel hub is not off it's index point as this crank does not have a key...but rather it has splines and a thicker master sline to index the hub.

The magnets could not have shifted as they are encapsulated in a strong rubber compound and a steel ring. (I checked for possible movement)

And finally, yes, the trigger plate is about halfway through its' travel when I manage to get the idle timing right.

Sooooo....time to double and triple check the part numbers on the trigger, eh?

 

[philbur]

Re: V-6 200hp Blackmax Timing set-up

Hi Again guys:

Well...I went through it again and I have no other options then to surmize that either the replacement trigger and/or the replacement flywheel hub are the culprits.

The motor runs...and I have eliminated all the possible components other than these two...and the fact that both of them were sold to me from the same guy on ebay seems to point in that direction....

I could really use the contact info for a really good Mercury Parts supplier so I can sort out the proper part numbers and get these items ASAP....

Any suggestions?...I live in Ottawa Canada and the dealers here are more or less useless at verifying old part numbers and getting me the right stuff.

Thanls again...and I'll post back when I have a better idea if the components I have currently installed are, indeed, the correct ones.

 

[philbur]

Re: V-6 200hp Blackmax Timing set-up

FYI...I went to iBoats.Com store to see if the parts could be ordered through them....
And they are not able to help...seems like a lot of parts suppliers actually do not offer their insight and merely fulfill orders based on the customer-supplied part numbers....
Coming from an Auto Mechanics' background I find this a bit surprising...but oh well....who said you HAD to work for your money.

 

[CharlieB]

Re: V-6 200hp Blackmax Timing set-up

With your model and serial # you should be able to look up the correct factory #'s here

http://www.mercruiserparts.com/SelectProductLine.asp