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Alpha I GenII Outdrive slipping?

R

rl65028

Contributing Member
Bought a SEI 116 outdrive last march. Took it out july Fourth on river and it seemed like I had a slipping clutch ( plenty rpm no speed). Raised the outdrive took a look @ prop put it back down and somehow it resumed to normal. Got home took prop to shop he put a new hub in but said it really didnt look bad. Then I dont really use again till fall. Yesterday while cruising I had a brief sound like prop comeing out of water ( drive full down). and soon after was on my fishing spot. The way in started normal but then sound changed and speed started to degregate. By the time I got in I was getting 12 knots down from 25 and engine speed stayed pretty constant about 3600 rpm. Outdrive? Coupler? dunno. Any thoughts?
 
If the prop hub and the overall condition of the prop is good, Sounds like the coupler. How long did you run it with it slipping? Did the engine temp increase? Take a look behind the engine and look for signs of rubber dust or metal dust.
 
Your wanna-be A drive is a Dog Clutch engagement drive. These will either be fully engaged, or not.

I agree with the drive coupler idea since the prop has just been repaired.
Also, sometimes a partially submerged plastic bag can find it's way around a propeller, giving us the idea that a hub is slipping.
 
Docksidemarineservices said:
If the prop hub and the overall condition of the prop is good, Sounds like the coupler. How long did you run it with it slipping? Did the engine temp increase? Take a look behind the engine and look for signs of rubber dust or metal dust.
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Ran it at least half hour 12 nautical miles. Temp stayed constant 160. No plastic bag but did see some reeds and grass on outdrive. Dismissed the grass as the sound and speed change is drastic. Was going to pull engine anyway for Oil consumption and can not achieve WOT RPM. Supposed to be 4400 only get 4000. At WOT I can hear a light popping sound out carb. Timeing set for a total advance of 35 degrees BTDC @ 3000 rpm. 4.3 engine. This is a very low time engine from US engines Inc STAY AWAY. Very nasty owner after the sale. The 7 yr warrenty is non sense. Uses a qt of oil an hour.
 
V6 module gives 20 degrees plus initial . how does that add up to 35 degrees? Timing is waqy too much, that could account for the popping. As far as the oil , did you do the recommended breakin procedures?
 
Bt Doctur said:
V6 module gives 20 degrees plus initial . how does that add up to 35 degrees? Timing is waqy too much, that could account for the popping. As far as the oil , did you do the recommended breakin procedures?
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If you read total advance timeing per GM its about 35 degrees @ 3000 RPM. Timeing was originally set @ 8BTDC @ idle. popping was worse then. I,ve also changed carburater since. Now it only occurs @ WOT. Came up with the 35 after research. As far as break in I never did anything special. I know in aircraft engines we use special mineral break in oil which I inquired about with US engines and they told me no such thing. Ive been useing straight 30 wt full synthetic. Ive never seen 4400 RPM and I have a small prop on it. I looked for rubber around shaft today and found none but im still going with coupler theory.
 
Bt Doctur said:
V6 module gives 20 degrees plus initial . how does that add up to 35 degrees? Timing is waqy too much, that could account for the popping. As far as the oil , did you do the recommended breakin procedures?
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14 degrees plus the initial.

I think you need a trained set of eyes to go over this engine for you.
 
Actually got into a big dispute with US engine about timeing and I think he turned out to be correct. Although mercruiser recommends a total timeing of 22 GM recommends 35 to 38. The engine actually runs better than it ever has @ GM setting. Although at both settings WOT was still 4000. I suspect the popping may be intake valve too tight and hanging open a hair. reguardless Im ging to pull engine for coupler and probably tear it down. Do you know if I can use the roller rockers going back together? its a 1992 SN OD814677. Thank You Chris input is very appreciated.
 
rl65028 said:
If you read total advance timeing per GM its about 35 degrees @ 3000 RPM. Timeing was originally set @ 8BTDC @ idle. popping was worse then. I,ve also changed carburater since. Now it only occurs @ WOT. Came up with the 35 after research.
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This is a 4.3L engine, correct????
Are you using your OEM ignition timing specs????
Are you setting BASE advance only, and then calling it a day????

The 4.3L is a SBC in the V-6 version.
Most 4.3L's use the dreaded "full dished" pistons, of which do ZERO to combat detonation.
Even a well built SBC with a good quench dimension, would have trouble with this much spark lead @ 3,000 rpm.... and it would likely raise it's ugly head in the form of "Detonation".

IMO, you'd best go back to the drawing board.

You could rebuild this engine, and if you were to use the exact same ignition system (and I believe that 35* TA may be excessive), you may have a repeat of this.

We should set BASE advance, but we should also always always always verify our progressive advance and our TA.
I don't care which ignition system this would be...... EST, mechanical with points, Hall Effect, VR or Photo Eye.



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Based on the MANUAL,

Initial timimg is 8 degrees before top dead center. Advance from the timing module is 14-15 degrees.

Initial + timing module = ~ 22 degrees total advance in by 2500 rpms...

8 + 14 = 22

See pic attached, from manual.
 
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Thank you, kghost. That should help him with his TA number, and show him that 35* TA @ 3k rpm is just simply wrong, and is asking for trouble.

rl65028, please note that BASE or Initial advance is NOT included in the vertical scale of the ignition curve graph....., nor is it reflected in the line graphs.
This means that BASE or Initial advance must be added/included when doing the math.


However, when strobing the timing marks dynamically, it can't help but be included.
IOW, when we look at timing dynamically, what we see, is what we get.... so to speak.


Basically, it's no different than if this was a mechanically advancing system.
BASE is BASE... and the progressive and TA are on top of this (in other words... in addition to BASE).

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